19 
plotter. Absolute orientation was performed using thirty control 
points which resulted in a CMAS of .2 meter earth scale, with 
the photo scale being 1/15000. No attempt was made to correct 
for atmospheric refraction lens distortion, or film shrinkage. 
Profiles were spaced at .75mm in the model and points recorded 
every .25mm along the profile. Profiling was done automatically, 
using the correlator on the AS-11B-1, producing 187 profiles 
in about 5 hours. The total elevation range in the area covered 
by the orthophoto was about 4mm at a model scale of 1/15,000. 
Profiling accuracy at the 90% confidence level was one meter 
at ground scale. 
The orthophoto was produced from a portion of the model 
at 2X using a nominal print width of 1mm. (Figure 8) Forty- 
four photogrammetrie ground targets were then measured on the 
AS-11B-1. The orthophoto target coordinates were rotated, 
translated, and scaled to the NRC supplied ground control by 
a least-squares adjustment. The residuals produced a CMAS of 
33 microns referred to the input photography thus confirming 
the general accuracy level achieved in the first test. One 
might expect the first test to yield smaller residuals than the 
second since model control was used instead of absolute ground 
control. Thirty (30) reseaus randomly selected from the Sudbury 
model did indeed produce a CMAS of only 30u, when fit to their 
corresponding model coordinates. It should be noted however, 
that the California model contained more relief than Sudbury 
and that the California orthophoto was printed at a 2mm print 
width while Sudbury was done at 1mm. The latter essentially 
decreased the control available for the printer. 
3. Other Tests. 
A stereomate was made from the same photo used in 
printing the Sudbury orthophoto (Figure 9). Elevations were 
calculated from x parallex measurements made on the orthophoto- 
stereomate. The error in these elevations when compared to 
ground control resulted in a standard deviation of .9 meters. 
Marty Alice and J. Abshier of Bendix Research Labs 
have also evaluated a stereomate and orthophoto (Figures 10 and 11) 
which were produced from 1/50,000 6 inch focal length photo 
graphy over Fort Sill, Oklahoma. The model contained an 
elevation range of 4mm. The same photo was used for printing 
both the orthophoto and the stereomate. The resultant standard 
deviation of the elevation error derived from the orthophoto- 
stereomate was 2.2 meters. Bendix also evaluated their ortho 
photo in a manner similar to the California model and obtained 
a CMAS of 40 microns referred to the input photography. Tables 
1 and 2 give a summary of the orthophoto and stereomate tests 
to date.