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• Mr. Small <br />November 13, 2007 <br />Page 2 of 6 <br />Re: Town of Chapel Hill -Aerial Photography, Mapping and Related Services Agreement <br />2008 Color Orthophotography and Update Mapping <br />Scope of Work <br />Digital Aerial Photography <br />Sanborn will acquire digital aerial photography utilizing our Charlotte based flight crew, twin- <br />engine aircraft and Intergraph DMC large format digital mapping camera. The digital aerial <br />photography will be acquired utilizing Airborne GPS/Inertial Navigation System technology at <br />aground resolution of one-half foot or less. <br />Ground Control Surveying <br />Sanborn will utilize the existing NCGS and NGS published control network to the fullest <br />extent possible and supplement where necessary with new GPS surveyed control points. The <br />ground control surveying will be referenced to the NC State Plane Coordinate System, NAD <br />83/2001 and NAVD 88. The unit of measurement will be the US Survey Foot. <br />Fully Analytical Aerial Triangulation <br />Sanborn will perform a FART least square adjustment for all of the aerial photography <br />acquired under this project conforming NC Land Records Management specifications and <br />accuracy standards. <br />Digital Elevation Modeling <br />Sanborn will utilize the Town of Chapel Hill and Town of Carrboro 2003 DTM point; <br />breakline data and UNC at Chapel Hill 2007 DEM point, breakline data as a 3D surface model <br />in the orthophotography rectification process. Utilizing the 2008 digital aerial photography, the <br />. existing DTM will be updated in those areas having significant changes to reflect current <br />conditions. Sanborn will utilize the NC Flood Plain Mapping Programs lidax data as a 3D <br />surface model in the orthophotography rectification process for the rema;,,i.,g portions of <br />Orange County. <br />Digital Terrain Modeling <br />Sanborn will develop a new DTM surface model for the 32 -1"=50' scale tiles being flown for <br />the UNC at Chapel Hill high resolution orthophotography product. The DTM will consist of <br />3D mass points and break lines at a density to comply with FGDC spatial accuracy standards <br />for one-foot contour mapping. <br />Color Orthophotographp <br />Sanborn will develop one-half foot resolution color digital orthophotography covering the <br />entire 400 square mile Orange County plus a minimum of 500 feet beyond the County <br />boundary. The total color orthophotography coverage area will be 470.8 square miles and will <br />include 525 - 5000' X 5000' tiles conforming to the NC Land Record Management's modular <br />tiling scheme for 1"=200' scale maps. The 525-orthophotography tiles will include full aerial <br />imagery coverage. <br />Topographic Update Mapping <br />Utilizing the 2008 aerial photography, Sanborn will update the Town of Chapel Hill's <br />designated twenty-four (24) 1"=100' scale tiles developed under the 2003 aerial photography <br />project. The planimetric, DTM and contour features included in the 2003 geodatabase design <br />will be updated to reflect current conditions. <br />Color Oblique Imagery <br />Pictometry will provide all of the color oblique imagery under this Agreement conforming to <br />the Town's and County's direct negotiations with Pictomehy. <br />t <br />