1:28,800 scale aerial photography with airborne GPS was acquired April 14 to May 17, 2005 with a LMK1000 aerial amera system equipped with six inch focal length lens. The imagery was scanned at 14 microns directly from the aerial negatives.
The aero triangulation process utilized an airborne gps survey undertaken during the flight to provided geodetic coordinates and elevation of photo centers. Also, image targeted ground control points where visible on the 2005 aerial flight and were used as control. Aerial triangulation was performed using softcopy workstations and Mira Solutions AT bundle adjustment program, Mira-AT. Details of the aerial triangulation process can be found in the Montgomery County, New York 2005 Orthophoto Update Project Aerial Triangulation Report.
For the 2002 orthophoto project only minimum DTM was collected in the center area of each aerial photo model creating an uneven distribution of terrain data throughout the project area. This process created what has been called "donut-holes" in the DTM and limited the usefulness of the data set for future ortho photo projects and other applications for this level of DTM. The 2005 project requirement was to fill in these sparse areas of DTM to create a consistent pattern digital terrain points throughout the project area. This was done by using a softcopy workstation with the AMSA-Softcopy program, overlaying the existing DTM on the stereo model and then adding points or breaklines to create a uniform level of digital terrain data. During this process the aerial photography was inspected for new roads and bridges that required collection of a bridge polygon that was used to correct the shape of the bridge during the orthophoto process. The photo inspection was assisted by information provided by Montgomery County as to the location of new roadways since 2002.
The images were then ortho rectified using Mira Solutions Mira Ortho software. Mira Solutions Mira Mosaic program was used for the mosaicking, color balancing and tiling of the imagery. The Mira Solutions process produced the same effect for bridges as was required to meet the previous ortho photo project. Quality
control was maintained throughout the process using internal QA programs within the Mira Solutions suite of orthophoto production software. Final files were then compressed using MrSID. Final deliverables in TIFF format with TFW files and MrSID files where placed on DVD Media.