48 
Table 1. 
Tube S19930 
Tube S19931 
Standard Deviation of the Nominal 
Versus Calibrated Grid 
Similarity 
Affine 
X 
= 
4.9 pm 
X 
= 
3.7 ym 
y 
= 
3.6 
y 
= 
1.6 
R 
= 
6.1 
R 
= 
4.0 
X 
= 
4.0 
X 
= 
3.2 
y 
= 
2.6 
y 
= 
1.3 
R 
= 
4.7 
R 
= 
3.5 
Values are given at tube scale 
1 ym at vidicon tube = 3.9 meters at ground 
micrometers at tube scale (1 micrometer equals approxi 
mately 3.9 meters at ground scale). It is apparent that 
the affine transformation reduces the residuals 2 to 4 
micrometers (8 to 16 meters at ground) below those of the 
similarity transformation. Also the y direction has 
considerably less variability than the x direction. When 
comparing these results with those of Table 1 it appears 
that the result of producing the image film by the Electron 
Beam Recorder adds only 1 or 2 micrometers (4 to 8 meters 
at ground) to the residuals. 
Nominal Positions Versus Measured Positions. When the 
RBV image is re-created from magnetic tape it is 
"corrected" to the calibrated positions of the reseau 
intersections. Therefore, it might be expected that an 
adjustment of the measured intersections on the film to 
the nominal values would yield a larger variability than 
when adjusted to the calibrated intersections. The results 
(at tube scale) are shown in Table 3. 
Comparing these results with those from the adjustments of 
measured to calibrated, one sees that the similarity 
transformation produces slightly lower residuals for the 
former but the affine produces larger residuals. It 
appears from this if one confines oneself to a similarity 
transformation operation (e.g., simple enlargement) the 
nominal intersections will be sufficiently accurate. 
Image-to-Ground Adjustments 
Map Control. Ground control was taken from 1:24,000- 
scale topographic maps. The precise locations were chosen 
by comparing well defined map points with their corre 
sponding image points on the RBV film as viewed with a 
monocomparator. The Universal Transverse Mercator (UTM) 
coordinates were read and recorded to five meters using a 
metric coordinate reader. 
For 1:24,000-scale maps that meet National Map Standards, 
one may expect errors in position as large as 13 meters, 
which along with errors of identification approaching 10 
meters can cause errors in control as large as 25 meters 
and an RMS of 12 meters.