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<br />J <br />Orthorectification <br />nson-Frank & Associates, inc. <br />(A8) Surveying & Mapping Services <br />City of Santa Ana <br />This task involves orthorectifi cation of the raw digital raster images that were created by scanning <br />the aerial negatives. A number of image processing techniques are used to maximize the quality of <br />the deliverable images. <br />• -The unrectified raster images will be georeferenced to the DTM's using the field control, <br />analytical aerotriangulation and aerial camera data. The digital orthophotography will be <br />created by draping the unrectified raster images over their corresponding digital terrain <br />models. All relief displacement will be removed from the raw image files at ground level <br />on a pixel-by-pixel basis, yielding a set of orthorectified digital photo images. <br />• Mosaicking will be performed to ensure a perfect edge match between all orthophoto <br />sheet tiles. Creation of seam lines is performed interactively to ensure that no image <br />flaws result from seam lines passing through tall structures. <br />• Radiometric adjustment will be performed to balance and match color tones, brightness <br />and contrast of the imagery over the whole project. Histograms will be applied on a <br />project basis and not just to adjacent tiles, ensuring uniformity of tone over the entire <br />image database. Image editing software will be used to repair any minor flaws on the <br />imagery. <br />• The imagery will be tiled into sheets as desired by the City. The digital orthophoto <br />software will be instructed to output a COT file for each orthophoto tile. The completed <br />image data set will be written to CD-ROM disks for delivery to the City. Images will be <br />delivered in the format selected by the City, including ecw files if requested. <br />Ground /Field Topographic Surveys <br />This task involves the survey and data collection of any features to be picked up by crews in the <br />field. <br />5150 E. Hunter Ave. 18 Anaheim, CA 92807 <br />(714) 777-8877 alanfrar W$ftnr*1Mk.com FAX: (7141777-1641