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. 3. "Continued" . 4. New Castle to Parachute, Colorado 5. Rifle, Colorado . -2- vegetation, which made stereo visiDn of the ground very difficult. Horizontally, our X value is approximately twelve feet larger than the existing mapping. Our Y value is approximately two feet larger than the existing mapping. Cole Ventures tied into two points, 108, and 121 which Delta had used. Cole Ventures came up with vector errors of approximately twelve feet at each point. The differences in X and Yare as follDWS: PT 108 ~X + 7.08' vec. error = 11.15' ~Y + 8.61 PT 121 ~X 12.20' ~Y 1.83' vec error = 12.34' Cole Ventures could not explain why the two companies came up with different coordinates for the points. Both survey crews used the same Trig Station for control. This mapping had not been compiled at the time we mapped the area. Analytical Surveys did the analytical aerotriangulation in this area for Bell Mapping Company. We tied our control into their control and used it in the aerotriangulation. We also sent Bell the edge ti es from our mapping in Drder for them to ti e to our project. Thi s was previ ous ly mapped by Kucera in May 1980 at a scale of 1"=200', with a five foot contour interval. Vertically, we did not tie very well to this project. We varied! three feet at their spot heights. There didn't seem to be any consistency in being always higher/or lower at the spot heights. This difference could be explained on the assumption that Kucera probably compiled their maps from photography that was flown at a higher flying height then our phDtography. Horizontally the grid systems from the two sets of mapping seemed tD tie. It was hard to tell what the difference in X and Y were because the sepia mylar copies of Kucera's mapping shrunk a little.