Aerotriangulation: The measurement of the pass points, flight ties, and control data was performed on Leica XPRO Triangulation software, an automated aerial triangulation system. Pass and tie points were all derived automatically using a sophisticated autocorrelation algorithm. In locations where automation failed, manual measurements were made. Measurement adjustment was performed with a robust aerial triangulation software package on softcopy photogrammetric workstations. The final adjustment of the block was accomplished with a rigorous least squares bundle adjustment. The general procedure is to remove all blunders from the data using automatic blunder detection. The bundle adjustment is then run with minimal ground control to test the photogrammetric measurements for consistency. Next, the ABGPS data are added to the adjustment holding the horizontal control very loose and the vertical control very tight. Since horizontal control errors can affect the vertical control but not vice-versa, we can detect errors in the vertical control. The horizontal control is then tightened and the effects on the vertical control and the photogrammetric residuals are inspected. The final adjustment makes sure that all of the measurements are in balance with each other and properly represent the actual conditions.

Orthophoto Processing: Utilizing all four bands [blue (B), green (G), red(R), and infrared [I]] digital orthorectification was performed using bilinear interpolation algorithms resulting in a spatial and radiometric transformation of the digital image from line/sample space into NAD83 (2011), State Plane California II FIPS 0402, US survey feet. The interior and exterior orientation parameters from the aerotriangulation process were used to project each pixel into the ground coordinate system, while the ortho grade DTM was used to correct for relief displacement. Radiometric correction software and techniques were used to create orthophoto files that minimize the appearance of image seams and without loss of feature signature. Orthophotos are checked for geometric accuracy, image quality, and are tonally balanced to produce a uniform contrast and tone across the entire project. The individual overlapping orthophoto frames were mosaiced together.