BY USING THIS WEBSITE OR THE CONTENT THEREIN, YOU AGREE TO THE TERMS OF USE. The 1974 Historic Orthoimagery was derived from traditional orthophotography. Images will be in raster format. Original film negatives were cleaned, scanned, and diapositives were created from these scans. The digital files were stored on DLT tape. Files were uploaded to workstations for rectification and mosaicing. ERDAS Imagine Orthobase software was used to create a seamless county wide image. Elevation data from the 1997 photography was used in this process. The original 1974 was flown of an altitude of 1"=1000'.