Softcopy Photogrammetric Software to Investigate the 
Production of Digital Orthophotos 
F. L. Scarpace and F.A. Abanmy 
Department of Civil and Environmental Engineering 
Environmental Remote Sensing Center 
University of Wisconsin-Madison 
Madison, Wisconsin 53705 
ABSTRACT 
During our evaluations of commercial softcopy photogrammetric systems, the need for a 
softcopy software system that could be used to investigate each of the individual processes used to 
generate the orthophotos became evident. 
Our group has evaluated four commercial softcopy 
photogrammetric systems, one produced by Intergraph, one produced by Helava (marketed by Leica), 
and two systems produced by Visions International (Autometrics, Inc.). 
Because of our previous development of routines to easily display images within an OS/2 
environment, OS/2 was chosen as the operating system for development. The software was designed 
to be used in a windows like environment, the OS/2 Presentation Manager. All of the routines, except 
the display subroutines, are portable to other operating systems such as Windows NT or UNIX. The 
software is call SoftTest. 
1. DESCRIPTION OF FUNCTIONS 
The functions which are currently 
included in SoftTest are: (1) display up to four 
images simultaneously in either black and white 
or color, (2) perform interior and exterior 
orientation of digital images, (3) produce 
equivalent vertical digital images, (4) produce 
stereo epipolar resampled images, (5) determine 
individual match points on stereo pairs using 
correlation, (6) automatically create DEM from 
stereo epipolar images using correlation routines, 
(7) create digital orthophotos, and (8) make area 
and point measurements on images. The epipolar 
resampled images can be viewed in stereo using a 
stereoscope like attachment to the viewing 
screen. 
1.1 Image Display 
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An image virtually of any size can be 
loaded into memory and displayed on the screen. 
The software creates a bitmap of the appropriate 
size for the display. Images can be zoomed and 
panned. Color images are displayed with as many 
colors as supported by the video driver loaded by 
OS/2. If a digital ortho image is loaded, the 
ground coordinates at the cursor location are 
displayed as the cursor is moved. If a DEM 
image is loaded, the elevation as well as the 
ground coordinates are displayed as the cursor is 
moved. 
1.2 Interior Orientation 
Standard procedures are used for the 
interior orientation of images. A project is 
created which contains information on the camera 
calibration and locations of the fiducials. A 
reduced resolution copy of the whole image is 
displayed in the upper right corner. The user is