Natural Color imagery was collected at a photo scale of 1:15000 and scanned at 18 microns to generate the raw raster scans. Airborne GPS positions were computed by Photo Science, Inc. and used as control in the aerotriangulation process. The scanned aerial images, ABGPS data, ground check point data, and camera calibration data were used as inputs to the aerotriangulaton process. ISAT 04.05 was used to perform block adjustments and generate exterior orientation parameters for each photo. The external orientation parameters were used to provide the geospatial control each photograph during orthorectification. Vertical control for the orthorectification process was obtained from existing USGS Digitial Elevation Models (DEM). During the orthorectification process, elevation data were extracted and resampled to meet user-specified intervals and bounds.
The orthorectified imagery is resampled to a 0.3 meter ground resolution with a ground extent of 1500 meters by 1500 meters, without overlap. Each 1500-meter orthoimage was generated from a mosaic created from multiple photographs. Orthoproduction was performed using the Intergraph Ortho Pro 4.4.18. Seamlines were Manually Generated and tone balanced between frames prior to cutting out into 1500-meter products. The orthorectified imagery is georeferenced to UTM zone 16, NAD83, meters.
All orthoimages are individually inspected for content, misalignments along mosaic seamlines, and void areas. Source information was collected and verified manually during the production process.
The metadata were imported and updated for display through the Seamless Data Distribution System at <http://seamless.usgs.gov> Project level metadata are available in several formats: HTML, TEXT, XML, FAQ and SGML. Chip level metadata are available in XML format.