2 
Description - The APPS can be described as consisting of two major sets of 
components. A photographic data base with the associated orientation 
parameters and the mensuration and computation hardware. A more detailed 
illustration of the data base is shown in Figure 1. The photomosaic is a 
composite of approximatley 100 photographs of the general area of interest. 
The mosaic is used to identify and locate the specific stereo photographs 
needed for a particular application. The mosaic is normally at full 
photographic scale. The stereo imagery can be from any cartographic camera. 
In this instance, however, wide-angle cartographic photography was used. 
The photographs were at a scale of 1:100,000. The photographs are marked 
with index points and check points for instrument set-up and calibration. 
The magnetic tape cassette contains all of the numerical data and the 
computation programs. The numerical data include the photo identification 
numbers, camera position and orientation, camera calibration data and lens 
distortion corrections. 
The major components of equipment are shown in Figure 2. A Zeiss 
Stereotope and Bendix Datagrid Digitizer have been adapted for the 
mensuration of photography. The Stereotope is mounted on the Datagrid. 
The movement of the photo carriage relative to the digitizing surface is 
recorded by X and Y coordinates. The resolution of the Datagrid is 30^m 
in X and Y. The X control of the photo carriage has been modified by the 
addition of a shaft angle encoder to provide a digital output with a