228 
PHOTOGRAMMETRIC ENGINEERING 
Fig. 4C. Ortho-corrected photograph. 
2. In the Scan Mode, the system simul 
taneously scans and digitizes the overlap 
areas of a stereo pair (approximately 
4.5" X9"). The scanner is capable of 
scanning at resolutions of 16 or 32 spots 
per millimeter in x and y directions and 
is also capable of image-to-digital con 
version at levels of 8, 16, or 32 gray 
Fig. 5. Manually drafted contour map manuscript.