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nent was carried 
1 points as check 
d by reading the 
ints on the digital 
them with the 
ned by GPS. The 
nd figure 3 where 
epancies between 
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ire that there is an 
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; not as good as 
; Will be done to 
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Easting, m 
Figure 12. Discrepancies in the Coordinates of Control Points of Model 194-193 
Between Points Measured on the Orthophoto and Points Determined by GPS. 
associated with the generation of the DEM were 
much larger than expected. There is likely some 
type of error associated with the surface 
generation module, as the matching algorithm 
seems to give the correct results within the single 
point match option. The software is designed so 
that different matching algorithms can be tested 
for both accuracy and speed. As soon as we are 
convinced that all the components are error free, 
SoftTest will be put in use by our softcopy 
photogrammetry group. 
5. ACKNOWLEDGMENTS 
We would like to thank Dane County, 
the USDA Soil Conservation Service and the 
Wisconsin Land Information Board for their 
support of the project which provided the 
imagery. The Wisconsin Department of 
Transportation provided manually extracted 
DEMs that served as the bases for comparison 
to softcopy results. The display portion of 
SoftTest was donated by the WISCIMG 
project and was primarily written by Dr. Peter 
Weiler. We would also like to acknowledge 
the help of the professors and graduate 
165 
students in the Geo-Spatial Information 
Engineering area of the Civil and 
Environmental Engineering Department at 
UW-Madison for their efforts in the acquisition 
of ground control. 
6. REFERENCES 
Abanmy, F., Khamees, H., Scarpace, F. and 
Vonderohe, A 1995 “An Evaluation of DEM 
and Orthophoto Generation on Ortho MAX.” 
ACSM/ASPRS Annual Convention, Charlotte, 
pp 479-488. 
Ackerman, F. 1984. Digital image correlation: 
performance and potential Application in 
photogrammetry, Photogrammetric Record, vol. 
11, no. 64, pp. 429-439 
Ackermann, F. and M. Hahn, 1991. Image 
Pyramids for Digital Photogrammetry, ISPRS, 
Conference on digital photogrammetric 
systems, Munich, pp 43-58. 
Lemmens, M.J, 1988 “A survey on Stereo 
Matching Techniques,” ISPRS Commission V/6, 
Keyoto, Vol 27, pp. 11-23.