+ 
  
Step 2 may be omitted in all further operations as long as the same image 
separation is maintained and the same stereoscope is used. As the stereoscopic 
slope of the Supplementary Slope Model has a fixed parallax, any instrument 
measurements of this exaggerated angle of slope will be similar. lt is only the 
angle of true slope that this model represents in relation to diff erent focal lengths 
and/or photo bases that will vary. This change of angle of representative slope 
can be obtained from the table on the right member of the Supplementary Slope Model. 
(Example: If at a fixed separation and using the same stereoscope a consistent measure 
ment of the Supplementary Slope Model is 47°, then for photography with a focal 
length of 6 inches and a photo base of 3.5 inches this exaggerated angle of slope would 
represent a 15° angle of true slope. Fora focal length of 8% inches and a photo base 
of 3.2 inches this same measurement of angle of slope can be used and would represent 
a 22° angle of true slope.) 
3. Determine the exaggeration factor by referring the selected true angle 
of slope of the Supplementary Slope Model and the exaggerated measured angle of 
slope to the Slope Conversion Chart. All vertical lines on the chart represent degrees 
of true slope, all curved lines represent degrees of exaggerated slope, and all horizontal 
lines represent various exaggeration factors. To determine an exaggeration factor, 
locate the intersection of a line representing a true angle of slope with one representing 
an exaggerated angle of slope; and read the horizontal line representing an exaggeration 
factor. (Example: if a true angle of slope for the Supplementary Slope Model is 20° and 
the exaggerated angle of slope is 55° as measured by the Stereo-slope Comparator, the 
exaggeration factor would be 3.9).