Process_Description:
Direct digital capture using Leica ADS40 sensors
flown on a 5 minute line spacing with 35% lateral
overlap at 25,000 feet AMT. Download and imagery
QA/QC performed using Leica GPro software suite.
GPS/INS processing is performed using Applanix
PosPAC version 4.01. This provides both the
position and orientation of the sensor during
flight. The horizontal accuracy of the ortho-
rectified imagery is primarily determined by the
quality of the AT solution and the surface model
(digital elevation model or DEM). The horizontal
control is picked from USDA furnished mosaicked
DOQQs (mDOQQs) and vertical control picked from
the USGS DTED 2 DEM data. Aerial triangulation
was done using either the Leica GPro/ORIMA package
or the ISTAR processing package. In both cases
automatic generation of image points both along
strip and between strips is performed. These
points are combined with the manually measured
horizontal control and then a bundle adjustment
is performed. Orthorectification is performed on
the triangulated imagery on a strip-by-strip basis
using either Leica GPro or ISTAR processes. These
strips are rectified using the USGS DTED 2 DEM data.
Once the strips are rectified they are processed
in an automatic seam-line generation process to
mosaic the imagery together into a seamless product
both geometrically and radiometrically. This
seamless mosaic is cut into the DOQQ tiles with the
360m buffer. Each DOQQ is inspected for relative
horizontal accuracy with adjacent DOQQ tiles. A
sample of DOQQs is inspected for relative horizontal
accuracy with the USDA furnished mDOQQs. Completed
and approved DOQQs are assembled into a countywide
MrSID file, using a compression factor of 1:50. The
countywide MrSID mosaics are edge-inspected against
the prior generation county mosaics to ensure accuracy.