The NHAP photography were acquired at 40,000 feet above mean terrain and flight lines were centered on the 1:24,000-scale USGS map series. Two different camera systems were used; a 6 inch focal length lens was used to acquire B/W film at an approximate scale of 1:80,000 and an 8.25 inch lens was used to acquire CIR film at an approximate scale of 1:58,000. Images were captured 1981 - 1987, with most captured 1981 - 1985. Most capture dates were in March and April. Date reflects the last exposure date.
The NHAP film rolls were scanned at USDA FPAC BC GEO BRANCH using high resolution aerial roll film scanners. The images were scanned at a resolution of 12.5 microns (approximately 0.75 m GSD) in three spectral bands (RGB). The actual process date was not provided by the processor.
The individual image scans were provided to USDA FPAC BC GEO BRANCH for post processing into orthorectified image mosaics. USDA FPAC BC GEO BRANCH also provided nominal photo center coordinates for each image along with the camera calibration information. The USGS NED 10m DTM for CONUS was used in the orthorectification process. The workflow processes included the following steps: 1. Stage the scan files from USDA FPAC BC GEO BRANCH. 2. Stage camera calibration information from USDA FPAC BC GEO BRANCH. 3. Stage or compute approximate photo center coordinates (XYZ) and estimate initial exterior orientation angles. 4. Identify best available images for a given topographic tile (default is to use best available scan file). 5. Build image pyramids and statistics for each scanned image. 6. Complete soft copy aerotriangulation to estimate adjusted image exterior orientation. 7. Stage or extract photo control from USDA FPAC BC GEO BRANCH provide control point data or from best available NAIP imagery base maps. 8. Interpolate control point elevation using the NED 10m DEM from USGS. 9. Refine the block adjustment by introducing ground control points. 10. Perform QA review of block adjustment (target accuracy is +/- 10m relative to NAIP or control source. 11. Perform orthorectification of individual images. 12. Perform seamline extraction to define mosaic lines for the final seamless mosaic. 13. Perform the mosaicking of the image collection for a tile. 14. Perform a visual inspection of the agreement with control source or NAIP reference. 15. Perform clip to footprint 40 pixels outside the tile boundary. 16. Prepare the tile processing metadata. 17. Deliver data to USDA_FPAC_BC_GEO_BRANCH PROCESS DATE Varies
Orthophoto tiles were provided to NJOGIS by the New Jersey State Office of the USDA Nationl Resources Conservation Service (NRCS.) Three-band GeoTIFF quad tiles from USDA in UTM zone 18N, NAD83 were converted to three-band MrSID MG4 tiles, using Extensis GeoExpress 10.0.1. These images were indexed to create a three band, false color infrared WMS, using Extensis Express Server.