slant-range resolution was limited by the length of the transmitted pulses, and the ground-range resolution was further limited by the image foreshortening due to the obliquity of the images, the latter being about 5 times coarser than the along-track value, but values of those were not ones sought by this experiment. Surface features relatable to map features occurred so frequently in the images that the edges of all image swaths could be traced nearly continuously on the maps. Besides boldly map-identified large features such as urban development, highway patterns, canals, bridges, and airports, the images showed other viewer-identifiable cultural and natural mapped and unmapped items such as agricultural field patterns, drainage patterns, forested versus open areas (usually revealed by bright returns from near-range sides of wooded areas and shadows along their far-range sides), qualitative relief patterns (revealed by variations of slope tones), large surface-mining operations, and well-defined shorelines bordering no-return areas representing smooth water surfaces. In high-relief (mountain) areas, the obliquity effects produced irregular swath-edge lines on maps and similar "layover" of images of elevated surface features onto nearer-range and lower-elevation "map" locations. Some results of the experiment provided vivid demonstrations that images having Quill's detail (and even considerably coarser detail, such as that of the 14-years-later civilian SEASAT spacecraft) would indeed be useful for wide-area environmental monitoring and research studies of the earth and other planets. One especially notable such image showed, in spite of intervening dense cloud cover and very heavy rainfall, a clear depiction of not only the extent of flooding of a Pacific coastal area, but also the extent of the debris-laden invasion of a river's flood current several miles into the ocean, an information-gathering capability not otherwise available. Another pair of images, one from ascending orbit 24 and the other from descending orbit 30, showed changes in both the locations and rotations of movable Great Lakes ice during the 9½-hour interval between the two imagings. To preserve return-signal strength, Quill's range from its target areas had been minimized by using an unusually steep depression angle. The resulting images, therefore, had slant-range scales that were much foreshortened versions of the ground-range (mapping) scale of level terrain. While slant-range images provide a realistic perspective of terrain elevation variations, users of imagery usually prefer map-like images having nearly matching scales in both ground-range and along-track directions. Because the optical processor of that time did not have the capability