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The Alaska High Altitude Photography (AHAP) covers approximately 90% of the State of Alaska in 1:60,000 color infrared (CIR). The AHAP film rolls were scanned at United States Geological Survey (USGS), Earth Resources Observation and Sciences (EROS) using high resolution aerial roll film scanners. The images were scanned at a resolution of 25 microns (approximately 1,000 dpi) in three spectral bands (RGB). The individual image scans were provided to USDA FPAC BC GEO BRANCH for post processing into orthorectified image mosaics. USGS EROS Data Center and USDA FPAC BC GEO BRANCH also provided nominal photo center coordinates for each image along with the camera calibration information. Orthorectification processing used 5 meter Alaska Digital Elevation Models (DEMs) - USGS National Map 3DEP for vertical registration. Horizontal registration used the Maxar Technologies Vivid Basemap Imagery datasets for Alaska. The Maxar datasets were provided for AHAP processing by the US Department of Defense - National Geospatial-Intelligence Agency, National Reconnaissance Office, U.S. Geological Survey and the State of Alaska. The output orthomosaic tiles are rendered as a target resolution of 1.5 meter GSD and are delivered in a Decimal Degrees, Spheroid-WGS 1984, Datum-WGS 1984 projection for which the majority of the cell footprint falls. Horizontal accuracy of 10 meters at 95% confidence in lower elevation areas with cultural landmarks (urban areas) and 20 meters confidence in Glaciers/Mountains. The orthomosaic cells have a designed overlap of 100 meter buffer on all sides. File format LZW compressed GeoTIFF format. AHAP DOQ is 1:25,000 scale tile (7.5 degrees latitude by 15 degrees longitude). There was no attempt to color balance the mosaic images. Thus, significant differences in color, including striping between adjacent flight lines and images is present in the mosaics. Where multiple images were collected for a single design photo center, the newest available scan was used. Note that there are some areas that were not collected in the AHAP program collections. Multiple image dates of AHAP imagery may be within one image tile.
Purpose: To provide USDA-NRCS, its partners and the public with updated digital orthographic imagery from the Alaska High Altitude Photography (AHAP) program.
Creation Date: 19780101-19861231
Publication Date: 20220802
Revision Date: 20231024
Refresh Cycle: Updated periodically as new imagery becomes available
Version: 1.2.0
Change Log: Service deployed.
The Alaska High Altitude Photography (AHAP) covers approximately 90% of the State of Alaska in 1:60,000 color infrared (CIR). The AHAP film rolls were scanned at United States Geological Survey (USGS), Earth Resources Observation and Sciences (EROS) using high resolution aerial roll film scanners. The images were scanned at a resolution of 25 microns (approximately 1,000 dpi) in three spectral bands (RGB). The individual image scans were provided to USDA FPAC BC GEO BRANCH for post processing into orthorectified image mosaics. USGS EROS Data Center and USDA FPAC BC GEO BRANCH also provided nominal photo center coordinates for each image along with the camera calibration information. Orthorectification processing used 5 meter Alaska Digital Elevation Models (DEMs) - USGS National Map 3DEP for vertical registration. Horizontal registration used the Maxar Technologies Vivid Basemap Imagery datasets for Alaska. The Maxar datasets were provided for AHAP processing by the US Department of Defense - National Geospatial-Intelligence Agency, National Reconnaissance Office, U.S. Geological Survey and the State of Alaska. The output orthomosaic tiles are rendered as a target resolution of 1.5 meter GSD and are delivered in a Decimal Degrees, Spheroid-WGS 1984, Datum-WGS 1984 projection for which the majority of the cell footprint falls. Horizontal accuracy of 10 meters at 95% confidence in lower elevation areas with cultural landmarks (urban areas) and 20 meters confidence in Glaciers/Mountains. The orthomosaic cells have a designed overlap of 100 meter buffer on all sides. File format LZW compressed GeoTIFF format. AHAP DOQ is 1:25,000 scale tile (7.5 degrees latitude by 15 degrees longitude). There was no attempt to color balance the mosaic images. Thus, significant differences in color, including striping between adjacent flight lines and images is present in the mosaics. Where multiple images were collected for a single design photo center, the newest available scan was used. Note that there are some areas that were not collected in the AHAP program collections. Multiple image dates of AHAP imagery may be within one image tile.
Purpose: To provide USDA-NRCS, its partners and the public with updated digital orthographic imagery from the Alaska High Altitude Photography (AHAP) program.
Creation Date: 19780101-19861231
Publication Date: 20220802
Revision Date: 20231024
Refresh Cycle: Updated periodically as new imagery becomes available
Version: 1.2.0
Change Log: Service deployed.