previously stored profile information are considerably faster than those 
in the manually controlled on-line systems. This is demonstrated by the 
time reported for the following orthophoto systems: 
  
Kelsh K320 (10 mm slit), time for orthophoto production 
in off-line mode: 27 min. 
Kelsh K320 (5 mm slit), time for orthophoto production: 1 hr 15 min. 
Wild OR 1 (8 mm slit), time for orthophoto production: 30 min. 
A 
Zeiss GZ-1 (8 mm slit), time for orthophoto production: 50 min. 
Several participants submitted computer generated contour 
sheets. The time needed for computation and graphical presentation of these 
contours varied considerably for the different instruments and depends 
largely upon the size and characteristics of the computer, software, 
number of profile points used, quality of graphical presentation, etc. 
As an example, the time required to compute contour lines from 
the Kelsh K320 profile data was 3 minutes for 3 500 points, including 
smoothing and data rejection. A total of 2 minutes was required for 
computing the contours without smoothing and data rejection procedures. 
This computation was performedon the Univac 1108 Computer. The plotting 
in ink d the Calcomp GPCP plotter took 30 minutes for each contour sheet 
Fig. 5). 
The time required for computing the contours derived from the 
Wild PPO-8 profile data on the CDC 6600 Computer was reported to be 
approximately 14 minutes for 15 000 recorded points. The automatic 
scribing of the contour plot (Fig. 6) on the Contraves Coragraph DC2 took 
6 hours. 
The time required for automatic contour presentation on the 
Zeiss Electronic Contour liner using profile data, recorded on the glass 
storage plate, was 50 minutes (Fig. 7). The Gestalt Photo Mapper II 
contours (Fig. 4) were produced simultaneously with the orthophoto 
(total production time 1 hour). The contours produced by these two 
instruments at present require additional scribing for the final carto-' 
graphic printing. Obviously, the digital terrain information provided 
by the GPM can be used for computer generation of contours. Gestalt 
International Limited, however, did not submit the relevant data. 
Time information related to various operational phases as 
submitted by the participants is listed in Table VIII. 
Comparison of Image Quality 
This orthophoto experiment was not intended to provide detailed