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Johnson -Frank & Associates Inc <br />(A8) Surveying & Mapping Servfces <br />City of Santa Ana <br />(This step will not occur if the digital camera is employed) <br />Analytical Aerotriangaintion <br />This task involves the densification and verification of field control data in order to enable the aerial <br />imagery to be used for photogrammetric processes- <br />0 All point marking and reading will be performed digitally. All targeted ground control, <br />passpoints, checkpoints and drop points will be located, symbolized and marked digitally <br />on the raster images. <br />• Analytical aerotriangulation computations will be run using ORIMA software, which is <br />capable of performing block/bundle adjustments using a rigorous least squares analysis, <br />and possesses error detection and removal facilities. Corrections for lens distortion, earth <br />curvature, atmospheric refraction, and film shrinkage will be applied. <br />• The output X, Y and Z residuals for all control points and RMS errors for the entire <br />control network will be examined to ensure that they fall within the acceptable range for <br />the accuracy level of mapping selected by the City. <br />Digital Terrain Model Creation <br />This task involves creation of digital terrain models to support generation of contours and production <br />ofdigital orthophotos. <br />• Masspoints and breaklines will be extracted in the quantities and locations needed to <br />achieve the most accurate possible representation of the ground surface for production of <br />contours and orthophoto production, if needed. Bridges and overpasses will be correctly <br />modeled in 3D. <br />• Contours will be generated from the DTM's using Intergraph SiteWorks and displayed on <br />the graphics screen of a digital photogrammetric workstation. The operator checks the <br />contour set by viewing it in 3D with digital aerial imagery in the background. <br />5150 E. Hunter Ave. 16 Anaheim CA 92807 <br />(714) 777-8877 alanfrank@johnson-frank.corn FAX: (714) 777-1641 <br />