A total of 52 field controlled aerial photographic paper 
prints, and corresponding film transparencies at 1:80,000- 
scale were selected, covering the image area of the four 
RBV subscenes. Inspection of these photographs showed that 
a total of 47 points with position descriptions were suit 
able for controlling the mosaic. Eight of these 47 points 
were common between adjoining subscenes. Five additional 
points were also selected as tie-points between the 
subscenes. 
Transfer and Marking of Control 
Horizontal control points were directly transferred and 
marked from the field controlled film transparencies to the 
appropriate RBV subscene, by using a Kern PMG-2 Zoom Point- 
Transfer instrument. The zoom optics of the PMG-2 permit a 
scale difference of up to five times. As the scale ratio 
of RBV subscene to the aerial photographs was 6.33, the 
aerial photographs were reduced to a scale of 1:160,000. 
This reduction permitted the relative orientation of the 
control film transparencies to the RBV film transparencies 
for stereoscopic viewing in the PMG-2. The corresponding 
field control photograph was used to identify on the 
control transparency the exact location of each point. 
Each point was then marked, using the PMG-2's high-speed 
precision drill, with an aperture size of 40 micrometers. 
RBV Subscenes Measurements 
After the four RBV subscenes were marked, they were 
measured on a Kern MK2 Monocomparator. The marked points 
were easily identified through the monocular microscope 
which has 28 times magnification. An Altek AC 189 data 
acquisition system and Univac 1170 card punch recorded the 
measurements on cards for computer processing. 
Analysis of Subscenes 
The measured image points on each subscene were adjusted 
to the corresponding State plane rectangular coordinate 
values by means of a plane-to-plane similarity transforma 
tion program. This transformation produces a least square 
adjustment of the measured points to the control points. 
Inspection of the residuals showed that there was only one 
control point having excessively large residual errors. 
This was most probably due to misidentification from a 
field control photograph, and the point was therefore 
deleted. Individual measurement of subscenes A, B, C, and 
D at 1:500,000-scale resulted in residual mean square error 
(RMSE) from the similarity transformation. 
Subscene Horizontal Control Points RMSE 
A 
20 
50 m 
B 
2 
indeterminate 
C 
24 
43 m 
D 
11 
43 m 
Common tie points were also checked for comparison of 
adjusted coordinate values on adjoining subscenes. The 
measurements of the four subscenes were then processed 
together in a least square semianalytical block adjustment 
program.