DISP Yearly Satellite Photographic Mosaics of Greenland 1962-1963

Summary

The Declassified Intelligence Satellite Photographs (DISP) Yearly Satellite Photographic Mosaics of Greenland are composites of black-and-white photographs of Greenland taken from American satellites in 1962 and 1963. The mosaics provide details of ice sheet morphology, glaciers, rock outcrops, the coastline, and other features. The image mosaics are useful for comparing the extent and internal configuration of the Greenland ice sheet with current satellite data. The data set consists of one tagged image file (.TIF) for each year.

The mosaic images are available via FTP. The files are large: the 1962 mosaic image dimensions are 17,092 by 28,484 pixels and the file size is 464.3 MB. The 1963 image dimensions are 17,792 by 27,805 pixels and the file size is 471.8 MB.

Citing These Data

Zhou, G., Jezek, K. DISP Yearly Satellite Photographic Mosaics of Greenland 1962-1963. Boulder, CO: National Snow and Ice Data Center. Digital media.

Overview Table

Category	Description
Data format	Tagged image file (.TIF), one byte per pixel
Spatial coverage and resolution	Greenland, 140-m resolution
Temporal coverage	1962-05-15 through 1962-05-19, and 1963-08-29 through 1963-09-01
Tools for accessing data	Most browsers, graphics, or image editing applications will display the .TIF images
Grid type and size	Polar stereographic map projection
File naming convention	Naming convention is based on the year of the original photographs: DISP62_grlnd.tif and DISP63_grlnd.tif
File size	1962 image dimensions are 17,092 by 28,484 pixels, file size is 464.3 MB. The 1963 image dimensions are 17,792 by 27,805 pixels, file size is 471.8 MB
Parameter(s)	Compile archive photographs
Procedures for obtaining data	Data are available via FTP

Table of Contents

1. Contacts and Acknowledgments
2. Detailed Data Description
3. Data Access and Tools
4. Data Acquisition and Processing
5. References and Related Publications
6. Document Information

1.Contacts and Acknowledgments

Investigator(s) Name and Title

Dr. Guoqing Zhou
Department of Civil Engineering and Technology
Old Dominion University
Kaufman Hall, Rm 214
Norfolk, VA 23529

Dr. Kenneth C. Jezek
Department of Geological Sciences
and Byrd Polar Research Center
The Ohio State University
Columbus, OH 43210

Technical Contact

NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449  USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
e-mail: nsidc@nsidc.org

Acknowledgements

This research work is supported by a grant from the National Science Foundation (NSF) Office of Polar Programs (OPP) and a NASA Center of Excellence Grant for Historical Satellite Data.

2.Detailed Data Description

Format

The mosaics are tagged image files (TIFs).

File Naming Convention

Naming convention is based on the year of the original photographs: DISP62_grlnd.tif and DISP63_grlnd.tif

File Size

1962 image dimensions are 17,092 by 28,484 pixels, file size is 464.3 MB. The 1963 image dimensions are 17,792 by 27,805 pixels, file size is 471.8 MB

Spatial Coverage

1962 Mosaic Coverage:

	x (km)	y (km)
Upper Left	-727805.5625	-535256.375
Lower Right	981294.4375	-338556.375

1963 Mosaic Coverage:

	x (km)	y (km)
Upper Left	-808514.4375	-645039.4375
Lower Right	970585.5625	-3425439.4375

Spatial Coverage Map

A low-resolution thumbnail of the 1962 image mosaic

A low-resolution thumbnail of the 1963 image mosaic

Spatial Resolution

Images in these mosaics have resolutions (pixel size equivalent) of 100 m.

Projection

polar stereographic map projection
WGS84 spheroid and datum
longitude of central meridian: 315
latitude of true scale: 70 N
false easting (meters): 0
false northing (meters): 0

Temporal Coverage

The first mosaic consists of images taken in May, 1962. The second mosaic consists of images taken in August and September, 1963.

Error Sources

The cameras mounted on the ARGON satellite had a wide field of view, approximately 59°, which causes some image distortion. Because of the large area (2,800 km by 1,600 km) covered by each mosaic image, there is high earth-curvature distortion.

3.Data Access and Tools

Data Access

Data are available via FTP.

Cost

There is no fee to obtain the data.

4.Data Acquisition and Processing

In 1962 and 1963, the U.S. reconnaissance satellite ARGON recorded photographic images of Greenland. These and thousands of other images became available to the public in 1995 through an executive order signed by President Clinton. The principle investigators (PIs), Guoqing Zhou and Ken Jezek, developed the images to create a mosaic image of Greenland for each year. They used the Digital SAR Mosaic and Elevation Map of the Greenland Ice Sheet as control data.

Photographs were digitized and assembled into mosaics. Geometric distortions were corrected by using ground control points and the camera model in ERDAS IMAGINE software to orthorectify the images. The images were then resampled to a 100-m pixel size. Radiometric balancing and blending operations corrected for radiometric variations, using IMAGINE and ARCInfo software and proprietary algorithms and programs.

Theory of Measurements

The photographs provide high ground resolution (about 140 m) and extensive coverage. Ground swath is 556 km by 556 km. Many of the photographs contained cloud cover, so the investigators used photographs with the least amount of cloud cover.

Sensor or Instrument Description

Sensors were specially designed K-H 5 frame cameras that captured black-and-white photographs. These cameras were designed to ph maintain a precise geometrical relationship between the lens and the film. The film was brought into contact with the square frame of the inner lens cone prior to exposure.

Data Acquisition Methods

The 1962 mosaic consists of 24 orthorectified images from eight orbits acquired during the ARGON 9034A mission during 15-19 May, 1962. The 1963 mosaic is made of 36 orthorectified images from 14 orbits acquired during the ARGON 9058A mission in 29 August - 1 September, 1963.

Data Source

The United States government launched the secret reconnaissance satellites in the 1960s. The imagery was declassified on February 24, 1995 by President Clinton in the Executive Order "RELEASE OF IMAGERY ACQUIRED BY SPACE-BASED NATIONAL INTELLIGENCE RECONNAISSANCE SYSTEMS." The U.S. Geological Survey archives the original data.

Derivation Techniques and Algorithms

The DISP black and white films were digitized at 7μm resolution using a high-resolution scanner. The mosaic method required the latitude and longitude of the central point and four corner points for each image and a 70 percent overlap of neighboring images. The PIs applied corrections for geometric and radiometric distortions. See Processing Steps for the procedures they used.

Processing Steps

The investigators used several steps to orthorectify the images and correct for geometric and radiometric distortions.

1. Geometric rectification for orthophoto generation: Geometric distortions result from camera lens distortion, atmospheric refraction, earth curvature, and other factors. Earth curvature caused a significant distortion, so the camera model in ERDAS IMAGINE software was used to orthorectify the images. The lack of distinct and consistent outcrops as ground control points was a problem that was solved by using clusters of points in neighboring images having better ground control as reference points.
2. Quality control: Investigators checked for quality control on the orthorectified images by comparing features on the SAR mosaic. Relative accuracy was better than 200 m (two pixels) in most cases.
3. Radiometric balancing: Radiometric differences in the images are due mainly to differing weather conditions over the days the photographs were taken. Applying radiometric balancing and blending operations prevented a patchy or "quilted" appearance in the mosaic. These operations were developed in ERDAS IMAGINE and ARC Info software, as well as the investigators' own programs.
   
   An ARCInfo tool adjusted for brightness variations between adjacent photographs. The tool, a cubic Hermite function, calculates the weights for blending individual scenes along a specified buffer zone:
   
   W=1-3d²+2d³W
   
   G=W G₁+(1-W)G₂
   
   where W is the weighting function applied in the overlap area (its values range from 0 to 1), d is the distance of a pixel to the buffer line, which is normalized into 0-1, G₁ and G₂ are brightness values of neighboring images, and G is the final brightness value. The Hermite function is an S-shaped curve.
4. Adaptive filtering: Scanning the photographs for digitization introduced noise into the images. Since no existing filters met their requirements, the PIs developed a new one that works by locally adjusting the filter size and shape and weighting the output. (Zhou and Jezek, 2002.)
5. Bright strip removal: Some of the original photographs contained bright strips that affected the appearance of geographic features. To diminish the bright strips, the PIs determined the center line of the bright strip, then developed an algorithm that uses the neighboring areas to "blend" those features into the bright strip area.
6. Mosaic postprocessing: After the individual images were orthorectified using the above methods, the investigators created the mosaics and then performed additional processing. Their methods include noise filtering, and contrast enhancement via Gaussian transformation of the histogram.
7. Accuracy evaluation: The investigators re-verified the accuracy of the final photographic mosaics against the Digital SAR Mosaic and Elevation Map of the Greenland Ice Sheet from 1992.

5.References and Related Publications

Zhou, G. and K. Jezek, 2002. Satellite photographic mosaics of Greenland from the 1960s era. Int. J. Remote Sensing, vol. 23, no. 6, p. 1143-1159.

Zhou, G., K. Jezek, W. Wright, and J. Granger, 2002. Orthorectification of 1960s Satellite Photographs Covering Greenland. IEEE Trans. Geosci. and Rem Sens, vol 40, no 6, p. 1247-1259.

Slater, Philip N., Robert G. Reeves, editor-in-chief. Manual of remote sensing. 1st ed. Am. Soc. of Photogrammetry, 1975, vol. 1. Falls Church, VA.

6.Document Information

Acronyms and Abbreviations

The following acronyms and abbreviations are used in this document.

DEM	Digital Elevation Model
DISP	Declassified Intelligence Satellite Photographs
ERS-1	European Remote Sensing Satellite
NIMA	National Imagery and Mapping Association
NSF OPP	National Science Foundation Office of Polar Programs
SAR	Synthetic Aperture Radar

Document Creation Date

07 January 2003

Document Revision Date

31 January 2003

Document Review Date

27 January 2003

Document URL

http://nsidc.org/data/docs/daac/nsidc0118_greenland_disp.gd.html