A New Method of Archaeological Ruins Identification Based on CORONA Stereo Pairs

A New Method of Archaeological Ruins Identification Based on CORONA Stereo Pairs | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article A New Method of Archaeological Ruins Identification Based on CORONA Stereo Pairs Yixin Zhang, Ningyuan Wang, Jie He, Tao Zhang, Xin Zhang, Hongpeng Luo This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4203362/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract Three-dimensional (3D) stereo images can be generated via the computer-based image processing of CORONA stereo pairs. To a certain extent, important terrain and surface feature data extracted from these stereo images can improve the survey of archaeological sites and the identification and mapping of major landscapes. This study focuses on the identification of the Archaeological Ruins of Liangzhu City. An optical stereo model (red/blue stereo image) of the Liangzhu site was created through the computer-based mosaicking and processing of CORONA remote-sensing stereo pairs taken in the 1960s and 1970s. By importing the optical stereo model into mobile phones, tablet computers, and other mobile devices, the research team undertook real-time locating via human observation, on-site investigation, and image overlayduring field survey and identified several Liangzhu-period dams, some of which have been confirmed via archaeological field investigations. The research team later applied the same method to the identification of tombs in the site of the Mausoleums of the Six Emperors of the Southern Song Dynasty. The results further proved that this method is feasible and reliable and can be widely promoted and used for the identification of archaeological ruins. identification of archaeological ruins CORONA historical satellite image stereo pair optical stereo model real-time locating Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 1 Introduction The use of remote-sensing images for field surveys and exploration has become an important part of the preliminary stage of archaeological research. With the development of the global positioning system (GPS), users can pinpoint their locations using a wide range of available navigation applications (such as Amap, Baidu Map, and the BeiDou Navigation Satellite System) and professional GIS software (such as Ovitalmap and Map Plus). Some of these applications support user-defined layers, which allow users to import their data for real-time locating. In this study, the authors (the research team) applied this feature to archaeological field surveys and exploration. By importing the required image layers into mobile devices in advance, the research team was able to observe the features of archaeological ruins in the study area while on site based on the topographical characteristics presented by the image. Named after the town of Liangzhu in the Yuhang district of Hangzhou, Zhejiang, where it was discovered, the Liangzhu culture dates back about 4,300–5,300 years. It is regarded as the culmination of the Neolithic Age in the Taihu Lake area in the lower reaches of the Yangtze River. As a testimony to the 5,000-year history of Chinese civilization, the Archaeological Ruins of Liangzhu City (referred to hereinafter as the “Liangzhu site”) was added to the UNESCO World Heritage List in 2019. The study area features a relatively visible and concentrated distribution of Liangzhu ruins, which is helpful for archaeological ruins identification using remote-sensing images. Most of the Liangzhu-period ruins in the Taihu Lake area are clay or stone terraces that rise several meters above the ground surface. The terraces vary in height, indicating their grade and size. Waters and rice fields are distributed in lower regions around the terraces. This pattern has remained largely unchanged, and these terraces have been in use ever since they were built. Instead of levelling up the terraces and building new ones, people of later generations built upon the original terraces and carried out planting, processing, and other activities on the periphery of the terraces, thus preserving the early pattern of the archaeological ruins(Wang, 2011). Based on this feature, researchers believe that elevation is a key indicator for distinguishing the types and grades of Liangzhu ruins, as it can better reflect the original ruins distribution pattern in this area and is more effective in identifying ruins than high-definition satellite images and digital line graphs(Liu and Wang, 2016) . Water management was an important social activity for agricultural settlements. The builders of many now ruined structures similar to those at the Liangzhu site acquired a good knowledge of local hydrological features before they started construction. Liu Jianguo built a digital elevation model (DEM) for the Qujialing, Shijiahe, and Chenghe sites and for other major prehistoric settlements in Jianghan Plain. By identifying and analyzing the performance of the settlements in the hydrological environment, he was able to explain the structures and functions of these archaeological ruins(Liu, 2008). To some extent, therefore, elevation information can be used as an indicator of ruin patterns. However, given that most available DEM data can only reflect the topography of the modern environment, the ever-changing surface of plains, lowlands, and uplands in the Yangtze River Delta, and the vegetation and buildings, have to varying extents affected the accuracy of identification of archaeological ruins. From a professional perspective, the discovery and identification of archaeological ruins cannot be achieved without a balance between factors such as the timeline of landform evolution, data accuracy, easy access to data, efficient data processing, and convenience in interpreting remote-sensing images for archaeological field workers. Considering the temporal and environmental characteristics of the Liangzhu site, the research team used stereo pairs of historical remote-sensing images to present the stereo effect of the archaeological ruins instead of building a DEM based on digital topographic maps or aerial survey data. At present, Keyhole (KH) satellites are the only source of historical remote-sensing images that have a high resolution and can be acquired easily. Among them, the CORONA images (mostly KH-4B images with a ground resolution of 6 feet) were taken mainly in the 1960s, when the study area had not yet undergone massive urban expansion and intensive agricultural development and the landforms could still reflect early surface features, thus providing an important basis for the identification of archaeological ruins. By comparing the CORONA image of the Liangzhu ancient city with that from Google Maps (as shown in Figure 1), one can see that the CORONA image, with clear layers and surface features, is as good as the one taken by modern commercial high-resolution satellites in terms of the details of houses and streets. CORONA images can display an archaeological landscape that no longer exists. In addition, CORONA data consist of stereo pairs, from which 3D images of landscapes can be generated. Elevation changes in the Earth’s surface are more visible in these images than in single images, making for easier identification of surface features. However, the extraction of DEMs from CORONA stereo pairs using photogrammetric methods still has many limitations and is rarely used in practice because of its low efficiency(Day et al., 1998). Were the research team to observe CORONA images with a stereoscope, the original CORONA stereo pairs could be used directly, without complex image processing procedures such as reference point selection and image correction. However, this method, whether conducted through the observation of printed CORONA images with a stereoscope or the observation of software-generated red/blue stereo images on a computer screen, would impose great limitations on stereo effect viewing and could not be applied directly in the field survey. Considering the research purpose, the time when CORONA images were taken, and the resolution, cloud fraction, price, and operability of the images, the research team, after collecting the CORONA images of Zhejiang province and the entire Yangtze River Delta, built an optical stereo model based on the CORONA stereo pairs of the study area at the Liangzhu site. During the field survey and exploration, the team imported the historical remote-sensing images and the optical stereo model of the study area into an application on their mobile devices and located the sites on the model using the GPS navigation system on these devices. With the help of red/blue glasses, the team performed on-site stereo observation to fully interpret the topography and surface features shown on the historical remote-sensing images, which facilitated the search for archaeological ruins. Actually, CORONA historical satellite images have been wildly used in archaeology studies (Casana, 2021)since it was declassified in late 1990s. Utilizations in Middle East archaeological investigation is in a large majority(Beck et al., 2007; Casana and Cothren, 2008; Casana et al., 2012; Challis et al., 2004; Kennedy, 1998; Kouchoukos, 2001; Philip et al., 2002; Ur, 2003; Wilkinson et al., 2006; M. J. F. Fowler, 2004), since archaeological sites dominate these alluvial landscapes with relatively heterogeneous land cover but with less vegetation are easily indentified in panchromatic images with high-resolution(Ur, 2013). While there are few other generally discussed cases in Europe (M. Fowler, 2004). From methodological perspectives, most of the utilization concentrate on discovering disappeared sites through manual interpretation by archaeologists. Recent developments take advantage of the large coverage of the CORONA data for building up historical land cover database(Casana, 2014, 2020). Only a few previous research considered stereo pairs collected by CORONA. Jesse Casana’s team in Dathmoth College adopted ortho-rectification technologies by various scholars and develop an online platform call “Sunspot”, which is mainly for create “a global CORONA atlas”(Casana, 2020) , but it is also proved to be available for generating high-resoluation DEM by photogrammetry( Casana and Cothren, 2008). Watanabe Nobuya worked with the authors’ team investigated the Liangzhu City and hydraulic system through similar approaches in stereo pairs but introducing both DEM with less accuracy than Casana’s work and stereoscopic viewing for a more intuitive perception for an archaeological sight(Watanabe et al., 2017). However, although remote sensing data, especially those high-resolution categories like CORONA, are mainly introduced in supporting field survey, but the whole survey procedure largely depends on indoors image investigation other than site identification. Therefore, all these efforts are desktop approaches and time-consuming. On-site efficiency seems not be the priority. Some researchers have adopted remote sensing technology for research on the Liangzhu site and proved its effectiveness. In particular, CORONA historical remote-sensing images and DEM data have played an important role in assisting the search for the walls, inner city ruins, and outer regions of the ancient city on the Liangzhu site. GIS elevation models and CORONA images have also provided key clues for the search for the overall structure of the massive hydrological system outside the ancient city and for the analysis of the structure, proving that the Liangzhu site has a palace/inner city/outer city structure and a large hydrological system on its periphery. Most of the remote-sensing images used for archaeological research on this area thus far have been two-dimensional (2D) images(Watanabe et al., 2017). When using CORONA remote-sensing stereo pairs for archaeological ruins identification, well-known scholars such as Watanabe Nobuya built DEMs using complex photogrammetric methods and did not turn the CORONA images into optical stereo models. 2 Methods The use of remote-sensing images to identify and analyze archaeological ruins should be based on a thorough understanding of the specific needs of the archaeological research and a good knowledge of remote-sensing images that are widely used in the field of archaeology. Appropriate computer-based image processing techniques can then be used to make the most out of the remotely sensed data and achieve in-depth research results. However, in previous archaeological research, CORONA images were often used as 2D images for interpretation. Furthermore, when stereo pairs were derived from CORONA images, they were often interpreted indoors with a conventional stereoscope. This method not only imposes strict requirements on observation sites and equipment but also requires experienced satellite image interpreters, which has to some extent increased the difficulty of archaeological information interpretation. The research design of this paper, as shown in Fig. 2 , addresses the aforementioned problems. First, the research team obtained the remote-sensing images of the study area, pieced them together, and applied computerized processing, including image alignment and adjustment, mosaicking of multiple images, and image registration based on a base image. After checking the registration accuracy, the research team imported the stereo pairs into optical stereo modelling software to produce a red/blue stereo image. Having ensured that the stereo image had a satisfactory stereo effect, the research team prepared for the field survey and exploration of archaeological ruins by importing the optical stereo model into mobile phones, tablet computers, or other mobile devices and entering its coordinates. 2.1 Acquisition of stereo pairs Stereo pairs of the study area were mainly acquired from the website of the United States Geological Survey (USGS). As the study area is located exactly at the junction of two serial images, it was necessary to obtain two front-view images (DS1106-2086DA078 and DS1106-2086DA079) and two rear-view images (DS1106-2086DF071 and DS1106-2086DF072). 2.2 Three-dimensional image adjustment The acquired stereo pairs cannot be directly used to build an optical stereo model. Because of factors such as different lighting conditions, there may be obvious differences in the hue and shade of images of different areas, which will affect image interpretation, result in patches and seams in the composite image, or in severe cases make the composite image obsolete. As CORONA images are high-resolution panchromatic images, the grey-level information of surface features is important for computer-based image interpretation. Therefore, CORONA images need to be processed to become clear and evenly colored. Tests showed that the best stereo effect was achieved by ensuring color consistency between the stereo pairs used for producing a 3D stereo image. First, the research team smoothed and feathered the images through histogram equalization. At the same time, to ensure that the final images were balanced in color, without seams, ghosting, or other defects, the images were processed in professional image editing software using techniques such as radiation correction, de-overlapping, hue adjustment, brightness adjustment, and contrast adjustment, to make the image pairs consistent in grey value before exporting the stereo pairs. The images before and after hue adjustment are shown in Fig. 3 against the base image. 2.3 Image mosaicking The original CORONA KH-4B satellite images are 70 mm wide and 756.92 mm long ( https://www.usgs.gov/centers/eros/science/usgs-eros-archive-declassified-data-declassified-satellite-imagery-1?qt-science_center_objects=0#qt-science_center_objects ). Therefore, each KH-4B image purchased from the USGS website is usually split into four images numbered with a suffix (a, b, c, and d), with about 1/5 to 1/4 of each image overlapping (Fig. 4 ). As the study area is quite large and is distributed across images, it was necessary to piece together these images after hue adjustment. The images were merged into a composite image as required, with the decision of whether to rotate based on a comparison with the actual surface features (Fig. 5 ). It should be noted that mosaicking images manually is not efficient for a large study area involving a high number of images. Given the relatively uniform format of KH satellite images, a program can be used to merge the images in a batch. A Python program has been written and tested by the research team for this purpose and can be used when necessary. 2.4 Image registration A key step for 3D model building, image registration is required to give a 3D stereo image accurate geographical coordinates. As the global navigation satellite system had not yet been developed in the 1960s, there were no ephemeris data to refer to when images were taken by KH satellites. As a result, the CORONA images do not carry any location and direction information. Affected by cruising altitude and attitude, operating speed, and the Earth’s curvature, the built-in sensors might also generate varying degrees of geometric distortion to the images, resulting in a mismatch between elements on these images and their counterparts on the ground in shape, size, and height. Therefore, the research team had to assign accurate geographical coordinates to the CORONA images before using them. For this task, the method of correcting distorted CORONA images against a base image with accurate geographical coordinates was used. This registration method involves the selection of the base image and same-name control points. Because of agricultural development and urbanization in the Yangtze River Delta, the CORONA images captured in the 1960s no longer reflect the actual landscape of the study area, which has undergone huge changes over the past half-century. If a modern satellite image were used as the base image to register historical images, it would be difficult to select same-name control points and ensure registration accuracy. Instead, an image from the less accurate 1960s basic aerial image library provided by the Zhejiang Provincial Platform for Common GeoSpatial Information Services (MAPWORLD) was used as the base image. By selecting ground control points (GCPs), the research team estimated and corrected the distortion in CORONA stereo pairs. Because of the photographic equipment used, the distortion in CORONA images is nonlinear, which means the distortion of different parts of an image varies greatly. Therefore, GCPs across the image, instead of just several corner coordinates, should be selected for overall correction. When using a base image to correct CORONA images, the spatial distribution, quantity, and accuracy of the selected GCPs will directly affect the final image registration accuracy. For that reason, the selected GCPs must be relatively even in distribution, reasonable in quantity, and accurate in coordinates. In terms of quantity, GCPs should be selected based on the area that the images cover and the requirements for image registration accuracy. Too few GCPs will not meet the accuracy requirements, whereas too many GCPs will not only increase the workload but may also increase the number of total errors during fitting because of the errors of a few control points. In terms of spatial distribution, after the total number of GCPs is determined, efforts should be made to ensure that these GCPs, such as roads, bridges, buildings, and the meanders and center points of narrow rivers, are evenly distributed and easy to locate (see Fig. 6 ). Each composite image used in this study covers an area of about 3,000 square kilometers. After repeated tests and result comparison, the research team found that the ideal number of GCPs for such an image is 600. The specific quantities of GCPs were adjusted based on the actual situation: more GCPs were selected for flat areas where more archaeological ruins can be found and fewer GCPs for mountainous areas, where there will be fewer archaeological ruins. Furthermore, the number of GCPs for regions with complex terrains can be reduced because such regions make it difficult to accurately locate same-name control points and have lower accuracy requirements than plains. However, regardless of their quantity, the selected GCPs in the same area must be even in distribution with accurate coordinates to ensure accuracy in fitting and image registration. Produced primarily for archaeological field survey and exploration, the stereo image should be verified by superimposing it onto a digital image of modern surface features so that it can serve as a more precise guide for efficient archaeological ruins identification. To verify the effect of CORONA image registration, the research team superimposed a slightly transparent version of the image onto a Google Maps image reflecting the modern landform of the area to see how well the two overlap (see Fig. 7 ). To maximize the registration accuracy, the research team ensured that the linear surface features (each road and river, etc.) of the two images matched. 2.5 Optical stereo model production StereoPhoto Maker is a compact but versatile stereo image editor and stereo image viewer ( https://stereo.jpn.org/eng/stphmkr/ ). It supports a variety of image formats, including JPEG, BMP, TIFF, and MPO, and can automatically batch-align hundreds of images and load them into the “window.” The research team used the software’s built-in stereo image editor to display the stereo image by opening the left and right images and setting the bands—usually the red and blue bands (Fig. 8). The stereo image with a satisfactory stereo effect was then exported. By wearing red/blue glasses, the research team found that the stereo effect of mountainous areas was stronger and that of areas with minor topographic changes was weaker (Fig. 9 ). When the left and right images are set up, the red/blue stereo image may display a positive or negative landform. In case of a negative landform, a positive landform can be displayed by transposing the left and right images. Figure 8 Left and right stereo pairs displayed on StereoPhoto Maker Tests showed that provided that each selected GCP basically met the requirements for registration accuracy, the stereo effect presented by the red/blue stereo image would be closely related to the GCP density during image registration. Images with GCPs that were too sparse or too dense were more likely to show small abnormal bumps or dents in areas where no GCP was selected. Therefore, to achieve the best stereo effect, the research team needed not only to ensure GCP accuracy and density during image registration but also to adjust specific GCPs based on the stereo effect, especially in areas with special terrains (such as places where a mountain meets a plain). 2.6 Import of images into mobile devices After being registered as described in Section 3.4, the image had accurate geographical coordinates. Once a 3D stereo image was created using stereo pairs that met the registration accuracy requirements, the research team imported the optical stereo model into a map application supporting custom map layers on a GPS-enabled mobile device (such as a mobile phone or a tablet computer) by entering its coordinates. Map Plus, a mobile GPS navigation and map application, was selected for this study. This powerful iOS-based free map application supports world map viewing, searching, navigation, custom maps, offline maps, GPS track recording, KML/GPX/SHP/DXF file editing and processing, favorites collection, and photo management ( https://duweis.com/zhcn/mapplus.html ). By entering the red/blue stereo image’s xmax , xmin , ymax , and ymin coordinates (Fig. 10 ), the research team imported the image into Map Plus on a tablet computer to match the image with the real geographical location. 2.7 Field survey and adjustments During the field survey, tablet computers with a satellite system were used for real-time locating by enabling the Display Location feature on Map Plus. The imported stereo image was displayed on the screen in the positive coordinate direction (Fig. 11 ). Given that the stereo pair had been taken from different angles, because the satellite may have changed its trajectory at any time, the research team needed to adjust the angle from which the stereo image is viewed on the tablet to obtain the best stereo effect during the field survey. For instance, the images used to build the optical stereo model of the Liangzhu site were captured in the northwest to southeast orientation from an angle of about 6 degrees north by east. Therefore, when producing a stereo image using the overlapping parts of the stereo pair shot by the front and rear cameras, the best stereo effect can be achieved by using the parallax of 6 degrees in the northwest to southeast orientation. After importing the red/blue stereo image into Map Plus, the mobile device was rotated clockwise by about 6 degrees to obtain the best stereo effect. 3 Results and Discussion After determining that the above method can play an important role in the rapid discovery of sites, we applied this method to two areas, Liangzhu and Shaoxing, for further validation. 3.1 Survey and discovery of dams at the Liangzhu site In March 2021, the research team used tablet computers that supported GPS navigation while conducting a field survey on the Liangzhu site. Wearing red/blue glasses, the team could clearly see the surface features from the 1960s and those of today at the same time. Through comparisons, the research team found that the landforms of many areas where ruins were located, as shown in the 1960s images, had been damaged, and thus it would be almost impossible to identify the landforms only by modern satellite images. A typical example is shown in Fig. 12 : wearing red/blue glasses and using the stereo image created for this study, the research team identified one suspected dam on the west of the low dam area and three suspected dams on the northeast of the Tangshan embankment of the large hydrological system around the ancient city on the Liangzhu site. Archaeological exploration has confirmed the existence of the dam on the west of the low dam area. Of the three suspected dams identified on the northeast of the Tangshan embankment, the two within the red ovals have been confirmed by archaeological exploration and the one circled in yellow remains to be verified through archaeological field survey. 3.2 Survey and discoveries of the Mausoleums of the Six Emperors of the Southern Song Dynasty After verifying the accuracy of the research method by applying it to the identification of dams at the Liangzhu site, the research team also used the method for research on the Mausoleums of the Six Emperors of the Southern Song Dynasty (“the Mausoleums”) to further verify its feasibility and reliability. Based on the acquired CORONA stereo pair of the site of the Mausoleums (DS1108-1070DA094 and DS1108-1070DF087), the research team obtained the area’s red/blue stereo image using the aforementioned methods and imported it into Map Plus. Through on-site identification, the research team used the optical stereo model to identify the ranges of suspected imperial tombs (as shown in the orange boxes labeled 1 and 2 in Fig. 13 ) that had not yet been identified. The site marked Box 2 has been verified as archaeological ruins by archaeological exploration and the site marked Box 1 remains to be verified in further archaeological surveys. 4. Conclusions This study did not follow the conventional practice of building photogrammetric DEMs based on stereo pairs taken by CORONA satellites. Instead, the research team turned to the now rarely used red/blue stereo image. Compared with the conventional approach, the method adopted for this study is more convenient and easier to implement because it involves lightweight data that is easier to interpret and is compatible with widely used devices, software, and platforms. In particular, this method can synchronize real-time locating by modern and historical satellite images, making it easier to identify archaeological ruins by comparing ancient and modern landforms. Archaeological workers can directly import the stereo pairs into mobile devices (such as mobile phones and tablet computers) that support real-time locating. In the survey area, they can synchronously observe the landforms from the same orthophoto angle and compare them with those from the 1960s to identify archaeological ruins. In fact, the research team created a digital sand table that overlays the image of landforms in the 1960s and the image of the present-day ground as a new and more economical way to search for and accurately locate archaeological ruins for field survey. The foregoing results for the identification of archaeological ruins at the Liangzhu site and the Mausoleums of the Six Emperors of the Southern Song Dynasty fully prove the feasibility of the research design and method adopted for this study. Furthermore, the research team found that the surface features are greatly exaggerated in the optical stereo model built using CORONA stereo pairs, making it easier for field researchers to identify subtle terrain differences and thus providing more reliable evidence for ruins identification. This finding further validates the advantages of the research method. The research method has the potential for wider use because it can improve the accuracy of the generated stereo pairs and can simplify the processing and reduce the difficulty of image generation and interpretation. It also enables the direct observation of stereo pairs during field surveys, which enhances the efficiency of locating the range of archaeological ruins and identifying the landforms of archaeological sites. This method can provide important clues and evidence for archaeological field surveys, exploration, excavation, archaeological research, and cultural heritage protection. Some regions in China have now established databases of historical base images. For example, Jiangsu and Zhejiang have created databases of province-wide registered base images from the 1960s. The use of these images with the research method proposed in this paper can greatly improve the efficiency of province-wide systematic field surveys and exploration. Declarations Author Contribution YZ conceptualized the research methodology and was involved in data acquisition, analysis and interpretation during the study, and was a major contributor in writing the manuscript.NW provided funding, designed the research idea, participated in the research process, and made many important recommendations.JH provided funding and detailed revisions to the paper.TZ did software related processing and presentation, and participated in field survey validation.XZ did work related to remote sensing image processing and interpretation.HL was involved in data processing and work related to survey confirmation. Acknowledgement I would like to thank Zhejiang Provincial Institute of Cultural Relics and Archaeology for providing the instrumentation and research conditions, as well as the USGS for providing the very useful remote sensing images, for the successful completion of this article. Of course, the conduct of the research also benefited from the financial support provided by China's National Key Research and Development Program project, the Zhejiang Provincial Bureau of Cultural Heritage, and Harbin Institute of Technology (Shenzhen). On top of these conditions, I would like to thank my supervisor Dr.Dong Shaochun for her guidance in remote sensing image processing, and many of my colleagues for their help in the application of remote sensing technology to archaeological investigations. In addition, Ms. Yuan Shiyu and Ms. Yang Ming contribute to the paper editing and figure drawing. References Beck, A., Philip, G., Abdulkarim, M., Donoghue, D., 2007. Evaluation of Corona and Ikonos high resolution satellite imagery for archaeological prospection in western Syria. Antiquity 81, 161–175. Casana, J., 2021. Rethinking the Landscape: Emerging Approaches to Archaeological Remote Sensing. Annu. Rev. Anthropol. 50, 167–186. Casana, J., 2020. 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Satellite imagery as a resource in the prospection for archaeological sites in central Syria. Geoarchaeology 21, 735–750. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 07 Apr, 2024 Submission checks completed at journal 01 Apr, 2024 Editor assigned by journal 01 Apr, 2024 First submitted to journal 01 Apr, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4203362","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":286384436,"identity":"c05b2083-0cbb-4ca5-b769-13859172f0cf","order_by":0,"name":"Yixin Zhang","email":"","orcid":"","institution":"Zhejiang Provincial Institute of Cultural Relics and Archaeology","correspondingAuthor":false,"prefix":"","firstName":"Yixin","middleName":"","lastName":"Zhang","suffix":""},{"id":286384438,"identity":"e5076b5c-16de-4530-85ca-2eacc6e666cc","order_by":1,"name":"Ningyuan Wang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAvElEQVRIiWNgGAWjYFCCAwyMDQw2PPzsDaRpSZOR7DlAgj1ALYdtDG44EKlcvvGM8csZv87zMNxgYPzwMYcoG86YWW7su83DOLuBWXLmNiK0MDOcMTN82HObh1nmABszLzFa2CBazvGwSSQQqYWH4Yzxww0/DvDwEK1FguFYGePMhmQeCZ6DzcT5RX7G4c0fe/7Y2dsfbz744SMxWhgkTphJMLaBWMDoIQ7wtz/+wPCHSMWjYBSMglEwMgEAk3U7j9d1NtMAAAAASUVORK5CYII=","orcid":"","institution":"Zhejiang Provincial Institute of Cultural Relics and Archaeology","correspondingAuthor":true,"prefix":"","firstName":"Ningyuan","middleName":"","lastName":"Wang","suffix":""},{"id":286384439,"identity":"31cd4c33-5371-4613-a664-028e767c1e4c","order_by":2,"name":"Jie He","email":"","orcid":"","institution":"Harbin Institute of Technology (Shenzhen)","correspondingAuthor":false,"prefix":"","firstName":"Jie","middleName":"","lastName":"He","suffix":""},{"id":286384441,"identity":"6d26f061-80b3-4cc1-80cc-b28e7bd57933","order_by":3,"name":"Tao Zhang","email":"","orcid":"","institution":"Zhejiang Provincial Institute of Cultural Relics and Archaeology","correspondingAuthor":false,"prefix":"","firstName":"Tao","middleName":"","lastName":"Zhang","suffix":""},{"id":286384442,"identity":"1cc1c948-b006-4ce0-bf80-dcf090615f01","order_by":4,"name":"Xin Zhang","email":"","orcid":"","institution":"Zhejiang Provincial Institute of Cultural Relics and Archaeology","correspondingAuthor":false,"prefix":"","firstName":"Xin","middleName":"","lastName":"Zhang","suffix":""},{"id":286384443,"identity":"eabebb3a-ab39-4528-b7f8-1c8c7a78e52b","order_by":5,"name":"Hongpeng Luo","email":"","orcid":"","institution":"Tianjin University","correspondingAuthor":false,"prefix":"","firstName":"Hongpeng","middleName":"","lastName":"Luo","suffix":""}],"badges":[],"createdAt":"2024-04-02 02:44:21","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4203362/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4203362/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":54178410,"identity":"b31c686d-b6dc-4983-b4ed-d820aa044548","added_by":"auto","created_at":"2024-04-05 16:13:42","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":477072,"visible":true,"origin":"","legend":"\u003cp\u003e(a) CORONA image of the Liangzhu ancient city (Image ID: DS1106-2086DA079)\u003c/p\u003e\n\u003cp\u003e(b) Modern image of the Liangzhu ancient city (Source: Google Maps)\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4203362/v1/a3f53a7c9ca718dae80b38fa.png"},{"id":54178409,"identity":"11a27708-60af-4f9c-9d00-fbc406dabe5f","added_by":"auto","created_at":"2024-04-05 16:13:42","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":76274,"visible":true,"origin":"","legend":"\u003cp\u003eResearch design and technical route\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4203362/v1/a6809696cdbb7b84457ba289.png"},{"id":54178411,"identity":"a5a904f6-79c8-4d28-acb5-e5ce3b0701ff","added_by":"auto","created_at":"2024-04-05 16:13:42","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":534185,"visible":true,"origin":"","legend":"\u003cp\u003eImages before hue adjustment (upper two) and after hue adjustment (lower two)\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4203362/v1/74bd582048b74e88dba4436a.png"},{"id":54179699,"identity":"ba490b1e-0226-4ad8-b886-d651c7e74011","added_by":"auto","created_at":"2024-04-05 16:21:42","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":142764,"visible":true,"origin":"","legend":"\u003cp\u003eOriginal images before mosaicking\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-4203362/v1/341e6e9e52f36a80c5c94f66.png"},{"id":54178420,"identity":"f1d3b765-86a6-4cb6-a9d4-0af44133564b","added_by":"auto","created_at":"2024-04-05 16:13:42","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":58595,"visible":true,"origin":"","legend":"\u003cp\u003eComposite image generated by mosaicking images a, b, c, and d and cutting the head and tail parts\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-4203362/v1/eb0bc16fcc52e61cf7590b8e.png"},{"id":54178421,"identity":"b8026b7d-20bd-46f1-b05c-68a745eb3d11","added_by":"auto","created_at":"2024-04-05 16:13:42","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":405103,"visible":true,"origin":"","legend":"\u003cp\u003eSelection of GCPs for image registration\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-4203362/v1/a1049fc1116f6633a283ffb8.png"},{"id":54178413,"identity":"71d8f5d4-4480-4da7-8a55-94a5a87d2adb","added_by":"auto","created_at":"2024-04-05 16:13:42","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":416503,"visible":true,"origin":"","legend":"\u003cp\u003eCORONA image superimposed onto a modern satellite image\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-4203362/v1/98cad0b083d63b4ae1b19021.png"},{"id":54178415,"identity":"02434caf-7b36-4bdc-829e-793feba068dc","added_by":"auto","created_at":"2024-04-05 16:13:42","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":261689,"visible":true,"origin":"","legend":"\u003cp\u003eLeft and right stereo pairs displayed on StereoPhoto Maker\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-4203362/v1/18e51419e94f1bd767795eeb.png"},{"id":54178417,"identity":"f949eb03-6525-4659-82d3-2529810c40e5","added_by":"auto","created_at":"2024-04-05 16:13:42","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":784175,"visible":true,"origin":"","legend":"\u003cp\u003eRed/blue stereo image of the Liangzhu site\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-4203362/v1/9e07da532b016e050629d0a0.png"},{"id":54179700,"identity":"3ba834e9-bcce-4d46-af2c-5d62c8c00e4b","added_by":"auto","created_at":"2024-04-05 16:21:42","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":363686,"visible":true,"origin":"","legend":"\u003cp\u003eImporting the red/blue stereo image into Map Plus\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-4203362/v1/fa7c35e8462ce0f103f08243.png"},{"id":54179701,"identity":"c050f809-a625-4925-aeb0-43e6f6b21b2b","added_by":"auto","created_at":"2024-04-05 16:21:42","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":655668,"visible":true,"origin":"","legend":"\u003cp\u003eStereo image loaded into Map Plus (left) and the default satellite image provided by Map Plus (right)\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-4203362/v1/f365e6338ce33a265f3a43e1.png"},{"id":54178422,"identity":"9e8c19e4-c4a4-476f-abd2-9f6df2f2a39c","added_by":"auto","created_at":"2024-04-05 16:13:42","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":676017,"visible":true,"origin":"","legend":"\u003cp\u003eOne suspected dam on the west of the low dam area (lower left) and three suspected dams on the northeast of the Tangshan embankment (lower right) at the Liangzhu site identified using CORONA stereo images\u003c/p\u003e","description":"","filename":"12.png","url":"https://assets-eu.researchsquare.com/files/rs-4203362/v1/50a280e710928eccc9eec779.png"},{"id":54178418,"identity":"5384d4ce-aaaa-45a9-a19d-d580ecb530b1","added_by":"auto","created_at":"2024-04-05 16:13:42","extension":"png","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":379606,"visible":true,"origin":"","legend":"\u003cp\u003eResults of tomb identification in the Mausoleums\u003c/p\u003e","description":"","filename":"13.png","url":"https://assets-eu.researchsquare.com/files/rs-4203362/v1/bcc6a57b1abdaff12ec0bb8b.png"},{"id":54180305,"identity":"b7d5ee95-259e-4004-872c-097063859c56","added_by":"auto","created_at":"2024-04-05 16:29:43","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":5686210,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4203362/v1/e3e33a1d-6d28-4fe3-bdc4-5c35b1fa2280.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"A New Method of Archaeological Ruins Identification Based on CORONA Stereo Pairs","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003eThe use of remote-sensing images for field surveys and exploration has become an important part of the preliminary stage of archaeological research. With the development of the global positioning system (GPS), users can pinpoint their locations using a wide range of available navigation applications (such as Amap, Baidu Map, and the BeiDou Navigation Satellite System) and professional GIS software (such as Ovitalmap and Map Plus). Some of these applications support user-defined layers, which allow users to import their data for real-time locating. In this study, the authors (the research team) applied this feature to archaeological field surveys and exploration. By importing the required image layers into mobile devices in advance, the research team was able to observe the features of archaeological ruins in the study area while on site based on the topographical characteristics presented by the image.\u003c/p\u003e\n\u003cp\u003eNamed after the town of Liangzhu in the Yuhang district of Hangzhou, Zhejiang, where it was discovered, the Liangzhu culture dates back about 4,300\u0026ndash;5,300 years. It is regarded as the culmination of the Neolithic Age in the Taihu Lake area in the lower reaches of the Yangtze River. As a testimony to the 5,000-year history of Chinese civilization, the Archaeological Ruins of Liangzhu City (referred to hereinafter as the \u0026ldquo;Liangzhu site\u0026rdquo;) was added to the UNESCO World Heritage List in 2019. The study area features a relatively visible and concentrated distribution of Liangzhu ruins, which is helpful for archaeological ruins identification using remote-sensing images.\u003c/p\u003e\n\u003cp\u003eMost of the Liangzhu-period ruins in the Taihu Lake area are clay or stone terraces that rise several meters above the ground surface. The terraces vary in height, indicating their grade and size. Waters and rice fields are distributed in lower regions around the terraces. This pattern has remained largely unchanged, and these terraces have been in use ever since they were built. Instead of levelling up the terraces and building new ones, people of later generations built upon the original terraces and carried out planting, processing, and other activities on the periphery of the terraces, thus preserving the early pattern of the archaeological ruins(Wang, 2011). Based on this feature, researchers believe that elevation is a key indicator for distinguishing the types and grades of Liangzhu ruins, as it can better reflect the original ruins distribution pattern in this area and is more effective in identifying ruins than high-definition satellite images and digital line graphs(Liu and Wang, 2016)\u003csup\u003e\u0026nbsp;\u003c/sup\u003e. Water management was an important social activity for agricultural settlements. The builders of many now ruined structures similar to those at the Liangzhu site acquired a good knowledge of local hydrological features before they started construction. Liu Jianguo built a digital elevation model (DEM) for the Qujialing, Shijiahe, and Chenghe sites and for other major prehistoric settlements in Jianghan Plain. By identifying and analyzing the performance of the settlements in the hydrological environment, he was able to explain the structures and functions of these archaeological ruins(Liu, 2008). To some extent, therefore, elevation information can be used as an indicator of ruin patterns. However, given that most available DEM data can only reflect the topography of the modern environment, the ever-changing surface of plains, lowlands, and uplands in the Yangtze River Delta, and the vegetation and buildings, have to varying extents affected the accuracy of identification of archaeological ruins.\u003c/p\u003e\n\u003cp\u003eFrom a professional perspective, the discovery and identification of archaeological ruins cannot be achieved without a balance between factors such as the timeline of landform evolution, data accuracy, easy access to data, efficient data processing, and convenience in interpreting remote-sensing images for archaeological field workers. Considering the temporal and environmental characteristics of the Liangzhu site, the research team used stereo pairs of historical remote-sensing images to present the stereo effect of the archaeological ruins instead of building a DEM based on digital topographic maps or aerial survey data. At present, Keyhole (KH) satellites are the only source of historical remote-sensing images that have a high resolution and can be acquired easily. Among them, the CORONA images (mostly KH-4B images with a ground resolution of 6 feet) were taken mainly in the 1960s, when the study area had not yet undergone massive urban expansion and intensive agricultural development and the landforms could still reflect early surface features, thus providing an important basis for the identification of archaeological ruins. By comparing the CORONA image of the Liangzhu ancient city with that from Google Maps (as shown in Figure 1), one can see that the CORONA image, with clear layers and surface features, is as good as the one taken by modern commercial high-resolution satellites in terms of the details of houses and streets.\u003c/p\u003e\n\u003cp\u003eCORONA images can display an archaeological landscape that no longer exists. In addition, CORONA data consist of stereo pairs, from which 3D images of landscapes can be generated. Elevation changes in the Earth\u0026rsquo;s surface are more visible in these images than in single images, making for easier identification of surface features. However, the extraction of DEMs from CORONA stereo pairs using photogrammetric methods still has many limitations and is rarely used in practice because of its low efficiency(Day et al., 1998). Were the research team to observe CORONA images with a stereoscope, the original CORONA stereo pairs could be used directly, without complex image processing procedures such as reference point selection and image correction. However, this method, whether conducted through the observation of printed CORONA images with a stereoscope or the observation of software-generated red/blue stereo images on a computer screen, would impose great limitations on stereo effect viewing and could not be applied directly in the field survey.\u003c/p\u003e\n\u003cp\u003eConsidering the research purpose, the time when CORONA images were taken, and the resolution, cloud fraction, price, and operability of the images, the research team, after collecting the CORONA images of Zhejiang province and the entire Yangtze River Delta, built an optical stereo model based on the CORONA stereo pairs of the study area at the Liangzhu site. During the field survey and exploration, the team imported the historical remote-sensing images and the optical stereo model of the study area into an application on their mobile devices and located the sites on the model using the GPS navigation system on these devices. With the help of red/blue glasses, the team performed on-site stereo observation to fully interpret the topography and surface features shown on the historical remote-sensing images, which facilitated the search for archaeological ruins.\u003c/p\u003e\n\u003cp\u003eActually, CORONA historical satellite images have been wildly used in archaeology studies\u0026nbsp;(Casana, 2021)since it was declassified in late 1990s. Utilizations in Middle East archaeological investigation is in a large majority(Beck et al., 2007; Casana and Cothren, 2008; Casana et al., 2012; Challis et al., 2004; Kennedy, 1998; Kouchoukos, 2001; Philip et al., 2002; Ur, 2003; Wilkinson et al., 2006; M. J. F. Fowler, 2004), since archaeological sites dominate these alluvial landscapes with relatively heterogeneous land cover but with less vegetation are easily indentified in panchromatic images with high-resolution(Ur, 2013). While there are few other generally discussed cases in Europe\u0026nbsp;(M. Fowler, 2004). From methodological perspectives, most of the utilization concentrate on discovering disappeared sites through manual interpretation by archaeologists. Recent developments take advantage of the large coverage of the CORONA data for building up historical land cover database(Casana, 2014, 2020).\u003c/p\u003e\n\u003cp\u003eOnly a few previous research considered stereo pairs collected by CORONA. Jesse Casana\u0026rsquo;s team in Dathmoth College adopted ortho-rectification technologies by various scholars and develop an online platform call \u0026ldquo;Sunspot\u0026rdquo;, which is mainly for create \u0026ldquo;a global CORONA atlas\u0026rdquo;(Casana, 2020)\u0026nbsp;, but it is also proved to be available for generating high-resoluation DEM by photogrammetry( Casana and Cothren, 2008). Watanabe Nobuya worked with the authors\u0026rsquo; team investigated the Liangzhu City and hydraulic system through similar approaches in stereo pairs but introducing both DEM with less accuracy than Casana\u0026rsquo;s work and stereoscopic viewing for a more intuitive perception for an archaeological sight(Watanabe et al., 2017).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eHowever, although remote sensing data, especially those high-resolution categories like CORONA, are mainly introduced in supporting field survey, but the whole survey procedure largely depends on indoors image investigation other than site identification. Therefore, all these efforts are desktop approaches and time-consuming. On-site efficiency seems not be the priority.\u003c/p\u003e\n\u003cp\u003eSome researchers have adopted remote sensing technology for research on the Liangzhu site and proved its effectiveness. In particular, CORONA historical remote-sensing images and DEM data have played an important role in assisting the search for the walls, inner city ruins, and outer regions of the ancient city on the Liangzhu site. GIS elevation models and CORONA images have also provided key clues for the search for the overall structure of the massive hydrological system outside the ancient city and for the analysis of the structure, proving that the Liangzhu site has a palace/inner city/outer city structure and a large hydrological system on its periphery. Most of the remote-sensing images used for archaeological research on this area thus far have been two-dimensional (2D) images(Watanabe et al., 2017). When using CORONA remote-sensing stereo pairs for archaeological ruins identification, well-known scholars such as Watanabe Nobuya built DEMs using complex photogrammetric methods and did not turn the CORONA images into optical stereo models.\u003c/p\u003e"},{"header":"2 Methods","content":"\u003cp\u003eThe use of remote-sensing images to identify and analyze archaeological ruins should be based on a thorough understanding of the specific needs of the archaeological research and a good knowledge of remote-sensing images that are widely used in the field of archaeology. Appropriate computer-based image processing techniques can then be used to make the most out of the remotely sensed data and achieve in-depth research results. However, in previous archaeological research, CORONA images were often used as 2D images for interpretation. Furthermore, when stereo pairs were derived from CORONA images, they were often interpreted indoors with a conventional stereoscope. This method not only imposes strict requirements on observation sites and equipment but also requires experienced satellite image interpreters, which has to some extent increased the difficulty of archaeological information interpretation.\u003c/p\u003e \u003cp\u003eThe research design of this paper, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003e, addresses the aforementioned problems. First, the research team obtained the remote-sensing images of the study area, pieced them together, and applied computerized processing, including image alignment and adjustment, mosaicking of multiple images, and image registration based on a base image. After checking the registration accuracy, the research team imported the stereo pairs into optical stereo modelling software to produce a red/blue stereo image. Having ensured that the stereo image had a satisfactory stereo effect, the research team prepared for the field survey and exploration of archaeological ruins by importing the optical stereo model into mobile phones, tablet computers, or other mobile devices and entering its coordinates.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Acquisition of stereo pairs\u003c/h2\u003e \u003cp\u003eStereo pairs of the study area were mainly acquired from the website of the United States Geological Survey (USGS). As the study area is located exactly at the junction of two serial images, it was necessary to obtain two front-view images (DS1106-2086DA078 and DS1106-2086DA079) and two rear-view images (DS1106-2086DF071 and DS1106-2086DF072).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Three-dimensional image adjustment\u003c/h2\u003e \u003cp\u003eThe acquired stereo pairs cannot be directly used to build an optical stereo model. Because of factors such as different lighting conditions, there may be obvious differences in the hue and shade of images of different areas, which will affect image interpretation, result in patches and seams in the composite image, or in severe cases make the composite image obsolete. As CORONA images are high-resolution panchromatic images, the grey-level information of surface features is important for computer-based image interpretation. Therefore, CORONA images need to be processed to become clear and evenly colored. Tests showed that the best stereo effect was achieved by ensuring color consistency between the stereo pairs used for producing a 3D stereo image.\u003c/p\u003e \u003cp\u003eFirst, the research team smoothed and feathered the images through histogram equalization. At the same time, to ensure that the final images were balanced in color, without seams, ghosting, or other defects, the images were processed in professional image editing software using techniques such as radiation correction, de-overlapping, hue adjustment, brightness adjustment, and contrast adjustment, to make the image pairs consistent in grey value before exporting the stereo pairs. The images before and after hue adjustment are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003e against the base image.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Image mosaicking\u003c/h2\u003e \u003cp\u003eThe original CORONA KH-4B satellite images are 70 mm wide and 756.92 mm long (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.usgs.gov/centers/eros/science/usgs-eros-archive-declassified-data-declassified-satellite-imagery-1?qt-science_center_objects=0#qt-science_center_objects\u003c/span\u003e\u003cspan address=\"https://www.usgs.gov/centers/eros/science/usgs-eros-archive-declassified-data-declassified-satellite-imagery-1?qt-science_center_objects=0#qt-science_center_objects\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e). Therefore, each KH-4B image purchased from the USGS website is usually split into four images numbered with a suffix (a, b, c, and d), with about 1/5 to 1/4 of each image overlapping (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003e). As the study area is quite large and is distributed across images, it was necessary to piece together these images after hue adjustment. The images were merged into a composite image as required, with the decision of whether to rotate based on a comparison with the actual surface features (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e5\u003c/span\u003e). It should be noted that mosaicking images manually is not efficient for a large study area involving a high number of images. Given the relatively uniform format of KH satellite images, a program can be used to merge the images in a batch. A Python program has been written and tested by the research team for this purpose and can be used when necessary.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Image registration\u003c/h2\u003e \u003cp\u003eA key step for 3D model building, image registration is required to give a 3D stereo image accurate geographical coordinates. As the global navigation satellite system had not yet been developed in the 1960s, there were no ephemeris data to refer to when images were taken by KH satellites. As a result, the CORONA images do not carry any location and direction information. Affected by cruising altitude and attitude, operating speed, and the Earth\u0026rsquo;s curvature, the built-in sensors might also generate varying degrees of geometric distortion to the images, resulting in a mismatch between elements on these images and their counterparts on the ground in shape, size, and height. Therefore, the research team had to assign accurate geographical coordinates to the CORONA images before using them.\u003c/p\u003e \u003cp\u003eFor this task, the method of correcting distorted CORONA images against a base image with accurate geographical coordinates was used. This registration method involves the selection of the base image and same-name control points. Because of agricultural development and urbanization in the Yangtze River Delta, the CORONA images captured in the 1960s no longer reflect the actual landscape of the study area, which has undergone huge changes over the past half-century. If a modern satellite image were used as the base image to register historical images, it would be difficult to select same-name control points and ensure registration accuracy. Instead, an image from the less accurate 1960s basic aerial image library provided by the Zhejiang Provincial Platform for Common GeoSpatial Information Services (MAPWORLD) was used as the base image. By selecting ground control points (GCPs), the research team estimated and corrected the distortion in CORONA stereo pairs.\u003c/p\u003e \u003cp\u003eBecause of the photographic equipment used, the distortion in CORONA images is nonlinear, which means the distortion of different parts of an image varies greatly. Therefore, GCPs across the image, instead of just several corner coordinates, should be selected for overall correction. When using a base image to correct CORONA images, the spatial distribution, quantity, and accuracy of the selected GCPs will directly affect the final image registration accuracy. For that reason, the selected GCPs must be relatively even in distribution, reasonable in quantity, and accurate in coordinates. In terms of quantity, GCPs should be selected based on the area that the images cover and the requirements for image registration accuracy. Too few GCPs will not meet the accuracy requirements, whereas too many GCPs will not only increase the workload but may also increase the number of total errors during fitting because of the errors of a few control points. In terms of spatial distribution, after the total number of GCPs is determined, efforts should be made to ensure that these GCPs, such as roads, bridges, buildings, and the meanders and center points of narrow rivers, are evenly distributed and easy to locate (see Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eEach composite image used in this study covers an area of about 3,000 square kilometers. After repeated tests and result comparison, the research team found that the ideal number of GCPs for such an image is 600. The specific quantities of GCPs were adjusted based on the actual situation: more GCPs were selected for flat areas where more archaeological ruins can be found and fewer GCPs for mountainous areas, where there will be fewer archaeological ruins. Furthermore, the number of GCPs for regions with complex terrains can be reduced because such regions make it difficult to accurately locate same-name control points and have lower accuracy requirements than plains. However, regardless of their quantity, the selected GCPs in the same area must be even in distribution with accurate coordinates to ensure accuracy in fitting and image registration.\u003c/p\u003e \u003cp\u003eProduced primarily for archaeological field survey and exploration, the stereo image should be verified by superimposing it onto a digital image of modern surface features so that it can serve as a more precise guide for efficient archaeological ruins identification. To verify the effect of CORONA image registration, the research team superimposed a slightly transparent version of the image onto a Google Maps image reflecting the modern landform of the area to see how well the two overlap (see Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e7\u003c/span\u003e). To maximize the registration accuracy, the research team ensured that the linear surface features (each road and river, etc.) of the two images matched.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Optical stereo model production\u003c/h2\u003e \u003cp\u003eStereoPhoto Maker is a compact but versatile stereo image editor and stereo image viewer (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://stereo.jpn.org/eng/stphmkr/\u003c/span\u003e\u003cspan address=\"https://stereo.jpn.org/eng/stphmkr/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e). It supports a variety of image formats, including JPEG, BMP, TIFF, and MPO, and can automatically batch-align hundreds of images and load them into the \u0026ldquo;window.\u0026rdquo; The research team used the software\u0026rsquo;s built-in stereo image editor to display the stereo image by opening the left and right images and setting the bands\u0026mdash;usually the red and blue bands (Fig.\u0026nbsp;8). The stereo image with a satisfactory stereo effect was then exported. By wearing red/blue glasses, the research team found that the stereo effect of mountainous areas was stronger and that of areas with minor topographic changes was weaker (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e9\u003c/span\u003e). When the left and right images are set up, the red/blue stereo image may display a positive or negative landform. In case of a negative landform, a positive landform can be displayed by transposing the left and right images.\u003c/p\u003e \u003cp\u003eFigure 8 Left and right stereo pairs displayed on StereoPhoto Maker\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTests showed that provided that each selected GCP basically met the requirements for registration accuracy, the stereo effect presented by the red/blue stereo image would be closely related to the GCP density during image registration. Images with GCPs that were too sparse or too dense were more likely to show small abnormal bumps or dents in areas where no GCP was selected. Therefore, to achieve the best stereo effect, the research team needed not only to ensure GCP accuracy and density during image registration but also to adjust specific GCPs based on the stereo effect, especially in areas with special terrains (such as places where a mountain meets a plain).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.6 Import of images into mobile devices\u003c/h2\u003e \u003cp\u003eAfter being registered as described in Section 3.4, the image had accurate geographical coordinates. Once a 3D stereo image was created using stereo pairs that met the registration accuracy requirements, the research team imported the optical stereo model into a map application supporting custom map layers on a GPS-enabled mobile device (such as a mobile phone or a tablet computer) by entering its coordinates. Map Plus, a mobile GPS navigation and map application, was selected for this study. This powerful iOS-based free map application supports world map viewing, searching, navigation, custom maps, offline maps, GPS track recording, KML/GPX/SHP/DXF file editing and processing, favorites collection, and photo management (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://duweis.com/zhcn/mapplus.html\u003c/span\u003e\u003cspan address=\"https://duweis.com/zhcn/mapplus.html\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e). By entering the red/blue stereo image\u0026rsquo;s \u003cem\u003exmax\u003c/em\u003e, \u003cem\u003exmin\u003c/em\u003e, \u003cem\u003eymax\u003c/em\u003e, and \u003cem\u003eymin\u003c/em\u003e coordinates (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e10\u003c/span\u003e), the research team imported the image into Map Plus on a tablet computer to match the image with the real geographical location.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e2.7 Field survey and adjustments\u003c/h2\u003e \u003cp\u003eDuring the field survey, tablet computers with a satellite system were used for real-time locating by enabling the Display Location feature on Map Plus. The imported stereo image was displayed on the screen in the positive coordinate direction (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e11\u003c/span\u003e). Given that the stereo pair had been taken from different angles, because the satellite may have changed its trajectory at any time, the research team needed to adjust the angle from which the stereo image is viewed on the tablet to obtain the best stereo effect during the field survey.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFor instance, the images used to build the optical stereo model of the Liangzhu site were captured in the northwest to southeast orientation from an angle of about 6 degrees north by east. Therefore, when producing a stereo image using the overlapping parts of the stereo pair shot by the front and rear cameras, the best stereo effect can be achieved by using the parallax of 6 degrees in the northwest to southeast orientation. After importing the red/blue stereo image into Map Plus, the mobile device was rotated clockwise by about 6 degrees to obtain the best stereo effect.\u003c/p\u003e \u003c/div\u003e"},{"header":"3 Results and Discussion","content":"\u003cp\u003eAfter determining that the above method can play an important role in the rapid discovery of sites, we applied this method to two areas, Liangzhu and Shaoxing, for further validation.\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Survey and discovery of dams at the Liangzhu site\u003c/h2\u003e \u003cp\u003eIn March 2021, the research team used tablet computers that supported GPS navigation while conducting a field survey on the Liangzhu site. Wearing red/blue glasses, the team could clearly see the surface features from the 1960s and those of today at the same time. Through comparisons, the research team found that the landforms of many areas where ruins were located, as shown in the 1960s images, had been damaged, and thus it would be almost impossible to identify the landforms only by modern satellite images. A typical example is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e12\u003c/span\u003e: wearing red/blue glasses and using the stereo image created for this study, the research team identified one suspected dam on the west of the low dam area and three suspected dams on the northeast of the Tangshan embankment of the large hydrological system around the ancient city on the Liangzhu site. Archaeological exploration has confirmed the existence of the dam on the west of the low dam area. Of the three suspected dams identified on the northeast of the Tangshan embankment, the two within the red ovals have been confirmed by archaeological exploration and the one circled in yellow remains to be verified through archaeological field survey.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Survey and discoveries of the Mausoleums of the Six Emperors of the Southern Song Dynasty\u003c/h2\u003e \u003cp\u003eAfter verifying the accuracy of the research method by applying it to the identification of dams at the Liangzhu site, the research team also used the method for research on the Mausoleums of the Six Emperors of the Southern Song Dynasty (\u0026ldquo;the Mausoleums\u0026rdquo;) to further verify its feasibility and reliability. Based on the acquired CORONA stereo pair of the site of the Mausoleums (DS1108-1070DA094 and DS1108-1070DF087), the research team obtained the area\u0026rsquo;s red/blue stereo image using the aforementioned methods and imported it into Map Plus. Through on-site identification, the research team used the optical stereo model to identify the ranges of suspected imperial tombs (as shown in the orange boxes labeled 1 and 2 in Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e13\u003c/span\u003e) that had not yet been identified. The site marked Box 2 has been verified as archaeological ruins by archaeological exploration and the site marked Box 1 remains to be verified in further archaeological surveys.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"4. Conclusions","content":"\u003cp\u003eThis study did not follow the conventional practice of building photogrammetric DEMs based on stereo pairs taken by CORONA satellites. Instead, the research team turned to the now rarely used red/blue stereo image. Compared with the conventional approach, the method adopted for this study is more convenient and easier to implement because it involves lightweight data that is easier to interpret and is compatible with widely used devices, software, and platforms. In particular, this method can synchronize real-time locating by modern and historical satellite images, making it easier to identify archaeological ruins by comparing ancient and modern landforms. Archaeological workers can directly import the stereo pairs into mobile devices (such as mobile phones and tablet computers) that support real-time locating. In the survey area, they can synchronously observe the landforms from the same orthophoto angle and compare them with those from the 1960s to identify archaeological ruins. In fact, the research team created a digital sand table that overlays the image of landforms in the 1960s and the image of the present-day ground as a new and more economical way to search for and accurately locate archaeological ruins for field survey.\u003c/p\u003e \u003cp\u003eThe foregoing results for the identification of archaeological ruins at the Liangzhu site and the Mausoleums of the Six Emperors of the Southern Song Dynasty fully prove the feasibility of the research design and method adopted for this study. Furthermore, the research team found that the surface features are greatly exaggerated in the optical stereo model built using CORONA stereo pairs, making it easier for field researchers to identify subtle terrain differences and thus providing more reliable evidence for ruins identification. This finding further validates the advantages of the research method.\u003c/p\u003e \u003cp\u003eThe research method has the potential for wider use because it can improve the accuracy of the generated stereo pairs and can simplify the processing and reduce the difficulty of image generation and interpretation. It also enables the direct observation of stereo pairs during field surveys, which enhances the efficiency of locating the range of archaeological ruins and identifying the landforms of archaeological sites. This method can provide important clues and evidence for archaeological field surveys, exploration, excavation, archaeological research, and cultural heritage protection. Some regions in China have now established databases of historical base images. For example, Jiangsu and Zhejiang have created databases of province-wide registered base images from the 1960s. The use of these images with the research method proposed in this paper can greatly improve the efficiency of province-wide systematic field surveys and exploration.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eYZ conceptualized the research methodology and was involved in data acquisition, analysis and interpretation during the study, and was a major contributor in writing the manuscript.NW provided funding, designed the research idea, participated in the research process, and made many important recommendations.JH provided funding and detailed revisions to the paper.TZ did software related processing and presentation, and participated in field survey validation.XZ did work related to remote sensing image processing and interpretation.HL was involved in data processing and work related to survey confirmation.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eI would like to thank Zhejiang Provincial Institute of Cultural Relics and Archaeology for providing the instrumentation and research conditions, as well as the USGS for providing the very useful remote sensing images, for the successful completion of this article. Of course, the conduct of the research also benefited from the financial support provided by China's National Key Research and Development Program project, the Zhejiang Provincial Bureau of Cultural Heritage, and Harbin Institute of Technology (Shenzhen). On top of these conditions, I would like to thank my supervisor Dr.Dong Shaochun for her guidance in remote sensing image processing, and many of my colleagues for their help in the application of remote sensing technology to archaeological investigations. In addition, Ms. Yuan Shiyu and Ms. Yang Ming contribute to the paper editing and figure drawing.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eBeck, A., Philip, G., Abdulkarim, M., Donoghue, D., 2007. Evaluation of Corona and Ikonos high resolution satellite imagery for archaeological prospection in western Syria. Antiquity 81, 161\u0026ndash;175.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eCasana, J., 2021. Rethinking the Landscape: Emerging Approaches to Archaeological Remote Sensing. Annu. Rev. Anthropol. 50, 167\u0026ndash;186.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eCasana, J., 2020. Global-Scale Archaeological Prospection using CORONA Satellite Imagery: Automated,Crowd-Sourced, and Expert-led Approaches. Journal of Field Archaeology 45, S89\u0026ndash;S100.\u003c/li\u003e\n \u003cli\u003eCasana, J., 2014. New Approaches to Spatial Archaeometry: Applications from the Near East. Near Eastern Archaeology 77, 171\u0026ndash;175.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eCasana, J., Cothren, J., 2008. Stereo analysis, DEM extraction and orthorectification of CORONA satellite imagery: archaeological applications from the Near East. Antiquity 82, 732\u0026ndash;749.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eCasana, J.,Cothren, J., Kalayci, T., 2012. Swords into Ploughshares:Archaeological Applications of CORONA Satellite Imagery in the Near East. Internet Archaeology 32.\u003c/li\u003e\n \u003cli\u003eChallis,K.,Priestnall, G., Gardner, A., Henderson, J., O\u0026rsquo;Hara, S., 2004. Corona Remotely-Sensed Imagery in Dryland Archaeology: The Islamic City of al-Raqqa, Syria. Journal of Field Archaeology 29, 139\u0026ndash;153.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eDay, D.A., Logsdon, J.M., Latell, B. (Eds.), 1998. Eye in the sky: the story of the Corona spy satellites, Smithsonian history of aviation series. Smithsonian Institution Press, Washington, D.C.\u003c/li\u003e\n \u003cli\u003eFowler, M., 2004. Archaeology through the keyhole: the serendipity effect of aerial reconnaissance revisited. Interdisciplinary Science Reviews 29, 118\u0026ndash;134.\u003c/li\u003e\n \u003cli\u003eFowler, M.J.F., 2004. Cover: Declassified CORONA KH-4B satellite photography of remains from Rome\u0026rsquo;s desert frontier. International Journal of Remote Sensing 25, 3549\u0026ndash;3554.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eKennedy, D., 1998. Declassified satellite photographs and archaeology in the Middle East: case studies from Turkey. Antiquity 72, 553\u0026ndash;561.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eKouchoukos, N., 2001. Satellite Images and Near Eastern Landscapes. Near Eastern Archaeology 64, 80\u0026ndash;91.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eLiu, B., Wang, N., 2016. The application of digital tools in archaeological work of large sites: Take Liangzhu ancient city as an example. China Cultural Heritage, 25\u0026ndash;29.\u003c/li\u003e\n \u003cli\u003eLiu, J., 2008. Archaeological mapping, remote sensing and GIS. Peking University Press.\u003c/li\u003e\n \u003cli\u003ePhilip, G., Donoghue, D., Beck, A., Galiatsatos, N., 2002. CORONA satellite photography: an archaeological application from the Middle East. Antiquity 76, 109\u0026ndash;118.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eUr, J., 2013. SPYING ON THE PAST: Declassified Intelligence Satellite Photographs and Near Eastern Landscapes. Near Eastern Archaeology 76, 28\u0026ndash;36.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eUr, J., 2003. CORONA Satellite Photography and Ancient Road Networks: A Northern Mesopotamian Case Study. Antiquity 77, 102\u0026ndash;115.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eWang, N., 2011. Exploration of the Peripheral Structure of Liangzhu Ancient City --Also on the Application of GIS and RS in the Archaeology of Large Sites, in: Proceedings of the Chinese Archaeological Society. Cultural Relics Press, p. 60.\u003c/li\u003e\n \u003cli\u003eWatanabe, N., Nakamura, S., Liu, B., Wang, N., 2017. Utilization of Structure from Motion for processing CORONA satellite images: Application to mapping and interpretation of archaeological features in Liangzhu Culture, China. Archaeological Research in Asia 11, 38\u0026ndash;50.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eWilkinson, K.N., Beck, A.R., Philip, G., 2006. Satellite imagery as a resource in the prospection for archaeological sites in central Syria. Geoarchaeology 21, 735\u0026ndash;750. \u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"npj-heritage-science","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"hsci","sideBox":"Learn more about [Heritage Science](http://heritagesciencejournal.springeropen.com)","snPcode":"40494","submissionUrl":"https://submission.nature.com/new-submission/40494/3","title":"npj Heritage Science","twitterHandle":"@SpringerOpen","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"identification of archaeological ruins, CORONA historical satellite image, stereo pair, optical stereo model, real-time locating","lastPublishedDoi":"10.21203/rs.3.rs-4203362/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4203362/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThree-dimensional (3D) stereo images can be generated via the computer-based image processing of CORONA stereo pairs. To a certain extent, important terrain and surface feature data extracted from these stereo images can improve the survey of archaeological sites and the identification and mapping of major landscapes. This study focuses on the identification of the Archaeological Ruins of Liangzhu City. An optical stereo model (red/blue stereo image) of the Liangzhu site was created through the computer-based mosaicking and processing of CORONA remote-sensing stereo pairs taken in the 1960s and 1970s. By importing the optical stereo model into mobile phones, tablet computers, and other mobile devices, the research team undertook real-time locating via human observation, on-site investigation, and image overlayduring field survey and identified several Liangzhu-period dams, some of which have been confirmed via archaeological field investigations. The research team later applied the same method to the identification of tombs in the site of the Mausoleums of the Six Emperors of the Southern Song Dynasty. The results further proved that this method is feasible and reliable and can be widely promoted and used for the identification of archaeological ruins.\u003c/p\u003e","manuscriptTitle":"A New Method of Archaeological Ruins Identification Based on CORONA Stereo Pairs","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-04-05 16:13:37","doi":"10.21203/rs.3.rs-4203362/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-04-07T12:56:48+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-04-02T03:01:04+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-04-02T03:01:04+00:00","index":"","fulltext":""},{"type":"submitted","content":"Heritage Science","date":"2024-04-02T02:32:13+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"npj-heritage-science","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"hsci","sideBox":"Learn more about [Heritage Science](http://heritagesciencejournal.springeropen.com)","snPcode":"40494","submissionUrl":"https://submission.nature.com/new-submission/40494/3","title":"npj Heritage Science","twitterHandle":"@SpringerOpen","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"4f7ce22a-c442-4f91-99e7-e64fba21934f","owner":[],"postedDate":"April 5th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2024-08-20T19:09:02+00:00","versionOfRecord":[],"versionCreatedAt":"2024-04-05 16:13:37","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4203362","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4203362","identity":"rs-4203362","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}