The images are in directory /honig/stereos in files earth.l.gif, earth.r.gif (stereopair), and earth.gif (raw data).
The images began as a 720 x 360 file of floating point elevations for the planet (found on hanauma.stanford.edu). Honig converted these to bytes to obtain a range image, a greyscale image. He used the 'rawtopgm' program to convert a headerless byte-file into .pgm format that can be read by his viewing program. View the images stereoscopically by running two copies of the viewing program (he uses 'xv').
Honig fed the range image and the elevation data to a program that added disparity info to the image. The disparity could be added by shifting the actual texture (the range image); or by superimposing a texture and shifting that. Various textures could be used.
(Honig used a texture with no pixel-by-pixel correlation. This was simple and yielded the smallest 'grain'. Several issues arise: should one use a constant-amplitude speckle noise, or should the noise amplitude vary with the pixel level (like quantum noise)? The problem here is that a constant amplitude will be large for dark pixels and unnoticable for bright pixels. Also, the dark pixels aren't seen. Using a scheme where speckle is added to small-valued pixels and speckle is subtracted from high-value pixels yields a form of gain control. This attentuates edges that are useful for stereo.)
Each method for adding disparity has its disadvantages. The problem with adding textures is that they degrade the greyscale image; the problem with shifting the images is filling in the resulting gaps, and a possible lack of features to match up for correspondence.
The images here have a pixel-disparity for every 250 meters of elevation difference. The noise has value -40, 0, or 40 greylevels.
It takes quite a while to achieve stereopsis for these images, but it can be done. The ocean floors and midoceanic ridges are particularly good. (Most of the relief of the earth is in the oceans.) The himalayas are probably too extreme to be fused, other ranges can be seen in depth.
The white artifacts are in the original data set.
Entry_ID: EARTH_LAND_UCI_STEREO_FTP1 (MD Identifier: 4237) Geographic Coverage: Southwest Extent: 90S,180W Northeast Extent: 90N,180E Source: SATELLITE Storage Media: on-line FTP Discipline, Subdiscipline: EARTH SCIENCE > LAND Location Keyword: GLOBAL Parameter Group, Parameter: BIOLOGICAL ENTITIES > SURFACE VEGETATION GEODYNAMIC FEATURES > STRUCTURES GEODYNAMIC FEATURES > TERRAIN ELEVATION GEODYNAMIC FEATURES > VOLCANOES GEOGRAPHY AND LAND COVER > CULTURAL FEATURES GEOGRAPHY AND LAND COVER > ELEVATION GEOGRAPHY AND LAND COVER > GLACIERS GEOGRAPHY AND LAND COVER > LAKES GEOGRAPHY AND LAND COVER > LANDFORMS GEOGRAPHY AND LAND COVER > RIVERS GEOGRAPHY AND LAND COVER > SURFACE VEGETATION GEOGRAPHY AND LAND COVER > SURFACE WATER GEOGRAPHY AND LAND COVER > TOPOGRAPHIC DATA GEOGRAPHY AND LAND COVER > WETLANDS HYDROLOGIC PARAMETERS > GLACIERS HYDROLOGIC PARAMETERS > RIVERS HYDROLOGIC PARAMETERS > SURFACE WATER HYDROLOGIC PARAMETERS > WETLANDS General Keywords: CARTOGRAPHY FTP GEOGRAPHY GEOLOGY IRVINE LAND COVER LAND USE MAPS PHOTOGRAPHY SATELLITE STEREO STEREO IMAGES STEREO PHOTOS TOPOGRAPHY UCI VEGETATION Science Review Date: 1994-01-11 Revision Date: 1994-01-11
Archive: UCI/FTP>U. of California, Irvine FTP site Contact: HONIG, DAVID Electronic Mail: INTERNET> firstname.lastname@example.org INTERNET> email@example.com
Entry Author: SHOTLAND, LAWRENCE M. Electronic Mail: INTERNET> LSHOTLAND@STX.COM INTERNET> SHOTLAND@NSSDCA.GSFC.NASA.GOV NSI/DECNET> NSSDCA::SHOTLAND Phone: (301) 441-4198 Information in this entry provided by UCI/FTP
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