7 
P-2546 
‘0. 
AO 
ACfr --O 
(a) 
(b) 
(c) 
LINE INTEGRAL 
POLYGON AREA 
IRREGULAR AREA 
Figure 3 - Distance and Area Measurements 
The second area-measuring routine could be used for any area, 
regardless of shape, but would require the operator to accurately 
trace the entire perimeter of the area. The size of the enclosed area 
would be automatically displayed whenever the operator returned the 
reference mark to the starting point on the boundary of the area. 
Figure 3b and 3c show the two types of areas that the above routines 
could readily measure. 
As a final example of computer operations which might be added 
to the standard AP-C stereoplotter functions, consider the problem of 
obtaining data for computing the volume of earth to be moved to build 
a highway. This is commonly referred to as the cut-and-fill problem. 
For a sample problem, assume that the instrument operator is given 
a set of stereo photographs and an over-lay which shows the prospective 
highway route. In addition, assume he wants to obtain, for every 20 
meters along the highway route, the X, Y, Z coordinates of a point on 
the center of the route and of points 10 meters on either side of the 
route. A relatively simple routine could be programmed to locate 
these cross-section points automatically, so that the operator would 
only have to follow the highway route and keep the reference mark in 
contact with the terrain. 
Figure 4 shows a portion of such a highway route and the points 
whose coordinates are desired. The operation of the automatic point- 
location routine might be as follows: First, the operator enters the 
distances along and to either side of the highway at which he wants 
points to be located (20 meters and 10 meters, respectively, in this 
example). Then, using the Veltropolo, he follows along the route to 
the location of the first point, which may be entirely arbitrary (point 1 
in Figure 4). After adjusting the elevation, he pushes the Punch