In 2008, San Juan County hired a M. J. Harden and Associates Inc. to take six (6) inch resolution orthoimagery countywide. This is the result of that project.Digital Orthophotographs are orthorectified aerial photographs. In this data set San Juan County, WA was flown at an altitude of 4800' AMT and orthorectified with a resolution of 0.5 feet.All imagery is visually inspected for completeness to ensure that no gaps, or image misplacement exist in the edge matched image sheets. The ortho images may be derived by mosaicking multiple images, in order to ensure complete coverage. Photo coverage for the 200 scale orthophoto's consists of 34 flight lines with a total of 2585 exposures flown at an altitude of 4,800 feet AMT. Overlap between each exposure is 60% with a 30% sidelap between flight lines. Photography is natural color RGB. TIFF image sheets are edge matched. Dataset includes 456 orthophoto's with .tfw files for the 200 scale photography.During the digital image post-processing, automatic dodging is performed to improve image quality. Dodging the images consists of balancing the radiometry of individual photographic exposures to eliminate flares and dark areas. The images are inspected to ensure clarity and radiometric uniformity. Image brightness values may deviate from brightness values of the original imagery due to image value interpolation during the post-processing and rectification processes. Radiometry is verified by visual inspection of the digital orthophoto quadrangle with the original unrectified image to determine if the digital orthophoto has the same or better image quality as the original unrectified input image.Aerial acquisition was performed using a digital mapping camera. Raw imagery post-processed as color RGB. Control Surveys - Existing Points selected and Supplemental Control planned by: MJ Harden Associates, Inc. 5700 Broadmoor Suite 800 Mission, KS 66202. Targeted and Surveyed by: San Juan County. Control supplemented with Airborne GPS IMU and data from one base station. US Survey Feet NAD 83 Washington State Plane - North Zone NAVD 88.

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  • By on August 17, 2016
  • Updated about 2 months ago

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