CORONA Atlas of the Middle East       BETA       Help      About   
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ABOUT

CORONA is the codename for the United States’ first photographic spy satellite mission, in operation from 1960-1972. During that time, CORONA satellites took high-resolution images of most of the earth’s surface, with particular emphasis on Soviet bloc countries and other political hotspots in order to monitor military sites and produce maps for the Department of Defense. The more than 800,000 images collected by the CORONA missions remained classified until 1995 when an executive order by President Bill Clinton made them publicly available through the US Geological Survey. Because CORONA images preserve a high-resolution picture of the world as it existed in the 1960s, they constitute a unique resource for researchers and scientists studying environmental change, agriculture, geomorphology, archaeology and other fields.

In regions like the Middle East, CORONA imagery is particularly important for archaeology because urban development, agricultural intensification, and reservoir construction over the past several decades have obscured or destroyed countless archaeological sites and other ancient features such as roads and canals. These sites are often clearly visible on CORONA imagery, enabling researchers to map sites that have been lost and to discover many that have never before been documented. However, the unique imaging geometry of the CORONA satellite cameras, which produced long, narrow film strips, makes correcting spatial distortions in the images very challenging and has therefore limited their use by researchers.

Thanks to grants from the National Endowment for the Humanities and the American Council of Learned Societies, the University of Arkansas’ Center for Advanced Spatial Technologies (CAST) has developed methods for efficient orthorectification of CORONA imagery and now provides free public access to our imagery database for non-commercial use. Images can be viewed online and full resolution images can be downloaded in NITF format.

IMAGERY

This project focuses on the Middle East and surrounding regions, areas where CORONA coverage is abundant and where its value to archaeology and other fields has been well-demonstrated. The large majority of the images we provide come from the KH4B satellites, the latest generation of CORONA missions in operation from September 1967 through May 1972. During this time, there were sixteen successful CORONA missions, designated 1101-1117 which recovered more than 188000 images. These satellites were equipped with two panoramic cameras, one facing forward and another aft with a 30º angle of separation, producing an approximate ground resolution of 6 feet (1.8m) at nadir as well as offering the capability for stereo-viewing and the extraction of topographic data. Images were originally recorded on black-and-white film, copies of which are curated by the USGS EROS Data Center. The USGS has scanned the images at 7 micron (3600 dpi) resolution. Additional technical details regarding the CORONA program and image characteristics can be read here.

Cameras on different CORONA missions produced images that vary a great deal in quality, while many images suffer from cloud cover, atmospheric haze or other issues. For imagery which we purchased, we have concentrated on providing the greatest possible regional extent, as opposed to multiple images of the same area, and have also sought to offer stereo coverage wherever possible. Imagery purchased for this project has been supplemented by images purchased for other projects or those shared with us by colleagues, notably the Center for Archaeology of the Middle Eastern Landscape (CAMEL) and the University of Chicago’s Oriental Institute.

Our work has been largely dedicated to developing methods for orthorectification of CORONA imagery. The technical aspects of this process are described in a forthcoming paper: Jackson Cothren, Jesse Casana, Tuna Kalayci and Adam Barnes, “An efficient method for rigorous orthorectification of CORONA satellite imagery” International Journal of Remote Sensing.

Images from our database reproduced in publications, presentations or online should be credited to: Center for Advanced Spatial Technologies, University of Arkansas/U.S. Geological Survey
 
Optimum Viewing

The CORONA Atlas is best viewed at a resolution of 1280 x 1024 or higher. According to our testing, Mozilla Firefox, Microsoft Internet Explorer 8 & 9, and Google Chrome display the Atlas correctly. There appear to be some problems when using Internet Explorer 7, it is recommended to upgrade your browser. Internet Explorer 6 does not function properly with this website.

Basic Navigation
  • Zoom In to an area by double-clicking the mouse or holding the shift key while drawing a box.
  • Zoom In/Out using the mouse scroll wheel.
  • Move/Pan around the map by holding the left mouse button while dragging.
  • Zoom to Default view by clicking the button in the Map Contents menu.
  • Bookmarking is possible in the Atlas. Use browser capabilities for saving specific locations.
Map Layer Visibility

At the default zoom level of the atlas, basic outlines representing the footprints for available CORONA images are displayed. As users zoom in to a larger scale, the CORONA images and archaeological sites become viewable.





Map Contents Menu

Map layers can be toggled using the Map Contents menu. Some map layers are expandable, allowing sub-layers to be turned on or off. Use the plus sign(+) next to a layer to access sub-layers. Use the blue down-arrow next to an image to download the source data.
Map Layers

Map layers include populated places in the Middle East, and modern political boundaries between countries. These layers help users to navigate in the area, and can be turned off at will.

Footprints Layer

Footprints layer contains the area covered by CORONA images. At lower scales, image footprints are merged to depict separate CORONA missions for easier viewing. In higher scales, users can investigate individual footprints and turn them on and off when navigating through these images. Footprint locations and coverage are estimated via photogrammetrical methods; they are accurate representations of image areas mapped on the ground in bowtie shapes.

Sites Layer

The Sites layer includes archaeological settlements in the Atlas. This layer remains inactive at lower levels in order to provide a clearer view of the coverage. Once a certain scale has been passed, the layer can be turned on/off at the user's will. Locations and naming conventions are obtained from Oxford Encyclopedia of the Near East, Atlas of PreClassical Upper Mesopotamia (APUM) and ANE Placemarks for Google Earth of Uppsala University. By adhering to these conventions, we hope to maintain standardization in the site inventory, and overcome further confusion by adding secure ancient names of settlements, if available and when possible..

Corona Layer

The Corona map layer contains all Corona images available for viewing and download. For efficiency this layer is only active at or below a certain zoom level, and is therefore not viewable when the Atlas is initially opened.

Images within the Corona map layer are organized by satellite revolution (or pass). During the collection of Corona imagery, a number of satellites were successively launched and each launch was counted as a new Corona mission. During each mission, the imaging satellite orbited around the earth a number of times -- each orbit was considered a separate revolution. The mission number and revolution number for each image are recorded in the image name. For example, image DS1105-1009DA003 was captured during mission 1105-1 and revolution 009. The last four characters (A003) tell us it was the third aft image taken during that revolution. Image acquisition dates are also provided in parenthesis, located in the parent mission-revolution names tab.

Nearly all images obtained for this Atlas were capture by the KH-4B CORONA instrumentation. Due to the stereo camera design of the KH-4 satellites, most revolutions available within the Atlas contain both forward and aft -- nearly 100% overlapping images (during some missions, one camera failed to return usable images). Beyond this, some revolutions overlap one another resulting in multiple views for any given location. Again, the Map Contents menu can be used to turn these layers on and off as the user desires.



Beyond overlapping fore and aft images, other forms of overlap exist and are important for the user to understand. The most basic of these is overlap between consecutive images (demonstrated by the red areas in the figure below). Another form of overlap results from revolutions overlapping one another (demonstrated by the blue areas in the figure below), resulting in multiple views for certain locations.



Due to the imaging geometry of CORONA, each image has a different, but compatible photogrammetric model. These models aim to reconstruct image-ground relations in the imaging sensor and are prone to variations as some of the physical camera parameters are not available. Therefore, spatial accuracy is not standard throughout the Atlas, and two CORONA images overlapping in an area may not perfectly match. In these cases selecting an image to download can be determined by visual inspection with the tools provided in the Atlas.

Tools Menu

By default, the tools menu is collapsed. To expand and view this menu, click the small circle to the left of "Tools."

There are three tools available within this menu: transparency, swipe, snapshot, and measurements.

Transparency Slider

The transparency slider allows the user to adjust transparency for the CORONA imagery. When the slider is on the left hand side, modern satellite imagery becomes more visible. As the slider moves to the right, on the other hand, the CORONA imagery becomes visually dominant.

Swipe

The swipe tool divides the area into two viewing parts, and enables user to view underlying layer without actually turning on and off layers. In this tool, the left view is dedicated to CORONA, and the right view is for the modern imagery. The user can swipe the images horizontally by pressing and catching the divider with the left mouse button.

Snapshot

The snapshot tool generates a CORONA image stored in portable network graphics (png) format. After navigating to a desired area, the user can utilize this tool to get a copy of the CORONA image with a spatial coverage defined by a bounding-box. The coordinates of this box are reported in the URL of the Atlas. The numbers reported here come from a WGS84 Web Mercator Projection, and represent the corners of the CORONA image in the viewer.

Measurements

The measure tool allows for location, distance and area measurements. Two-dimensional measurement results appear in different selectable units next to the measure button. Resulting location measurement is reported in geographic coordinate systems in degrees, minutes, and seconds.

To measure a line:

1. Click the line measurement tool.
2. Move cursor to the starting point, and left click.
3. Drag the mouse cursor across the measured distance.
4a. Double left click the mouse button if you want to end the measurement at the second point to create a line segment. Reported distance measurement is the length of that segment.
4b. If measuring multiple line segments, once the next point is reached left click once to add another point (vertex) to mark the location. Continue until the last node, and double click to finalize the measurement. Reported distance measurement is the sum of individual line segments.

To measure an area:

1. Click the area measurement tool .
2. Move cursor to the first point of the area, and left click.
3. Delineate the area by adding more points (vertices).
4. Double left click when the polygon defines the desired area. The result is reported in the tool area.

To locate a point:

1. Click the point tool.
2. Move cursor to the interest point, and left click.
3. The location is marked with a flag and reported in the tool area.

Archaeological Sites Menu

The Archaeological Sites Menu is an alphabetical list of known archaeological sites within the Atlas' region. The user may scroll through the drop-down menu to view the list of sites. Clicking the site name in the drop-down menu zooms to the site's location on the map. The name of the site is also displayed in the viewer which can be turned on and off from the Sites layer of the Map Contents.


Saving the Snapshot and Downloading

CORONA images can be acquired from the viewer in two ways.

1. Using Snapshot functionality located in the Tools creates screen images of the CORONA, ready for viewing. After the user clicks the snapshot button, the image opens in a separate browser. Browser functionalities then can be used to save the data locally in the PNG format. The stored image is orthorectified so that shapes are preserved.

2. Downloading spatially corrected CORONA imagery in its entirety is also possible through the Atlas. For these images, the data is stored in Imagery Transmission Format (NITF). The user can start downloading data to a local directory by clicking the arrow button located to the right of the CORONA image ID.


Using CORONA Images in Other Platforms

As an emerging standard, each National Imagery Transmission Format (NITF) file available for download contains one unprocessed CORONA image, along with a replacement sensor model (in the form of Rational Polynomial Coefficients - RPC) used to map the image to the ground. RPC information generated from inhouse control point measurements and software. Once fully downloaded, these images can be viewed in many Geographic Information Systems (GIS) software and remote sensing platforms. These images are not orthorectified, however, and require further processing. To help facilitate this process, we have prepared, and made available for download, SRTM DEM files for each Corona revolution
HERE. Information on using ArcGIS to orthorectify the NITF files using the provided elevation data can be found HERE.

As one of the main advantages of NITF, with some additional processing users can geometrically refine images if they provide additional ground control points number in various off-the-shelf photogrammetric software.

SRTM Credit:
Jarvis A., H.I. Reuter, A. Nelson, E. Guevara, 2008, Hole-filled seamless SRTM data V4, International Centre for Tropical Agriculture (CIAT), available from http://srtm.csi.cgiar.org (last accessed November 01, 2011)

Archaeological Inventory Credits:
S. Anastasio, M. Lebeau, and M.Sauvage (eds.) 2004. Atlas of PreClassical Upper Mesopotamia (APUM), Brepols Publishers.

Eric M. Meyers (ed.) 1996. The Oxford Encyclopedia of Archaeology in the Near East, Oxford University Press.

Olof Pedersen. ANE Placemarks for Google Earth, Uppsala University http://www.lingfil.uu.se/staff/olof_pedersen/Google_Earth/ (last accessed November 01, 2011)