Single Landsat scenes (and other space imagery) can be digitally converted into pseudo-stereo by merging the Landsat pixels with registered DEM data which can then be manipulated into view pairs having different parallax. Consider this Left-Right example in Morocco:

Astronauts using the Large Format Camera (LFC) flown on Space Shuttle Mission 41-G in October, 1984 (and subsequently) at an altitude of ~300 km (186 miles) snapped (both pre-planned and targets of opportunity) 2160 black and white and color/color IR photos (see Section 12). The photos as printed 1:1 comprise a 23 by 46 cm (9.2 by 18.4 inches) area, with ground resolutions between 14 and 25 m (46 and 82 ft). Taking these in quick succession allows along track forward overlap of between 20 and 80% from which excellent stereoviewing, at B/H of ~1.2, is attained. View the two LFC strips, cut from such a pair, that cover the Panamint Mountains and Death Valley in eastern California. The European Space Agency has flown a similar Metric Camera.

Adapted from T.E. Avery and G.L. Berlin, Fundamentals of Remote Sensing and Airphoto Interpretation, 5th Ed., Fig. 5-12, © 1992. Reproduced by permission of Macmillan Publishing Company, Indianapolis, IN.

The two HRV (High Resolution Visible) scanners on the SPOT satellites (see Section 3) can be tilted sidewards up to 27° in either direction. Not only does this permit wider coverage during a single pass (one of the HRV can stay in the vertical mode), but the off-nadir view can be combined with another view (either on- or off-nadir) taken on some other date to give rise to a stereo pair. A plateau on the Libyan/Tunisian border is imaged below from a panchromatic mode stereo pair acquired on February 23 and 25, 1986 at an off-nadirs angle of 24°E (right image) and and 10°W (left image).

For those who might like to see a striking stereo pair in color, taken by SPOT about 3 1/2 weeks apart, showing the Great Rift Valley of Kenya (note the step fracture zones), we have linked each of these (Top = Left) (Bottom = Right) which you can choose to print out on your color printer to examine either under a stereoscope or with your unaided vision. Again, you will probably have to move one or both until some segment in common to each is in proper position to induce the stereo effect.

Vis-IR scanners and SAR imagers are now being flown on spacecraft such as ERS-1 and ERS-2, JERS-1, and Radarsat, among others, and laser and radar altimeters are being planned for future flights. One prime task is to gather global sets of data that have a wide variety of topographic applications. An ultimate goal is to fill the current gaps in mapping of the Earth's land surface at more informative scales; a second objective is still better resolution profiles and elevation models of sea states within the major ocean bodies.

---

[an error occurred while processing this directive] [an error occurred while processing this directive]