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<br />f <br /> <br />May 23, 1975 <br />Weld County Planning Director <br />File No. P57-75 <br />Page 2 <br /> <br /> <br />Specifications for Aerial Photography for Photogrammetric <br />Mapping", published by the U.S. Geological Survey dated <br />January 15, 1972. The sca 1 e of the photography s ha 11 be <br />1" = 860'. <br /> <br />, <br />I <br />~ <br />I <br /> <br />~,' <br />! <br />f <br />f <br />! <br />I, <br />f <br />; <br />, <br />, <br />i' <br />i <br />i <br />, <br /> <br />Page 5: . Delete A & B and add following: <br /> <br />5. TOPOGRAPHIC MAPPING <br /> <br />A. Client shall specify the kind of map which shall either be a line <br />map showing contours and topographic features or one showing <br />contours with an orthophotographi c. sca 1 ed. ha lftoned background. <br /> <br />B. The finished map shall be on 4 mil mylar base positive photo- <br />graphic composite of negative scribed stable base material. <br />Contour compilation and cross sections will be performed on the <br />Hogan and Olhausen. P:C. Kern PG2 SSL Stereo Plotter. The plotter <br />is classified by the U.S.G.S. as a "First order compilation <br />instrument", suitable for compilation of 2' contours from photo- <br />graphy at 1" = 1000' with a 6" focal length. This is an equivalent <br />"c" factor of 3000. We propose to use a "e" factor of 2580, altitude <br />of 5160' and contact scale .of 1" = 860' f6r th~ project. The contour <br />interval will be 2' and the compilation scale will be 1" = 200'. <br />The image viewing Scale will be 1" = 107'. <br /> <br />( <br />~', . <br /> <br />Page 6: <br /> <br />D. Unchanged but with the following addendum: <br />In the event the photographic background option is selected by <br />the client. the work will be accomplished on the Hogan and Olhausen, <br />P.C. "Societe Francais Optique et Mechanique Orthophotographe" <br />instrument. The accuracy of pl animetry . wi 11 be checked by p 1 otti ng <br />appropriate outstanding identifiable planimetric features on the <br />Kern plotter during the compilation process and comparing the same <br />by overlaying the two manuscripts. Field checking of elevations <br />if carried out by the client, shall be performed in accordance' with <br />standard procedures outl ined in. the "Manual of Photogrammetry". as <br />published by the American Society of Photogrammetry. <br /> <br />Section 6-8-1: Change scale of photographs to 1" = 860'. <br /> <br />