Title: USDA-NRCS-FPAC BC GEO Digital Ortho HiRes County Mosaic-Natural Color
Originator: U.S. Department of Agriculture, Natural Resources Conservation Service
Abstract:
Most Recent - The image mosaic is the most recent available for the area that it
covers. There may be older (legacy) imagery of the same area. If older imagery exists, it can be ordered as
a separate product – look for “Legacy” in the Product Description on the Gateway Status Maps page or on the
WHAT page when placing an order.
Legacy - The image mosaic is an older (legacy) version available for the area that it covers. It could
be useful for temporal change investigations when compared with more recent imagery. There is newer imagery
available for the same area, and can be ordered as a separate product – look for “Most Recent” in the Product
Description on the Gateway Status Maps page or on the WHAT page when placing an order.
The natural color multispectral compressed county mosaics in this series were created using Erdas Imagine software. The input images range from 0.15 meter pixel resolution orthoimage tiles (approximately 6-inch GSD) to 0.6-meter pixel resolution orthoimage tiles (approximately 2-foot GSD) in GeoTIFF format. The projected coordinate system is UTM with a NAD83 datum. An orthoimage is remotely sensed image data in which displacement of features in the image caused by terrain relief and sensor orientation have been mathematically removed. Orthoimagery combines the image characteristics of a photograph with the geometric qualities of a map.
All files for the area of interest are processed into a consolidated mosaic using geo-referencing information from the input images. The range of compression applied to the mosaics varies from a compression ratio of 1:10 to 1:25 to save on storage requirements and to accelerate computer processing and display. All input images must be in the same UTM zone for MrSID software to create a mosaic. In areas split by a UTM zone, images in the lesser zone are reprojected to the dominant UTM zone using ERDAS Imagine or similar software. As appropriate, tone or range adjustments are made to minimize tone differences between individual tiles and along mosaic seam lines.
Purpose:
These data have been created as a result of the need for having geospatial data immediately available and easily
accessible in order to enhance the capability of Federal, State, and local emergency responders, as
well as plan for homeland security efforts.
These data are prepared for use by the NaturalResources Conservation Service for USDA Service Center personnel to administer agency programs.
Format: Raster - MrSID compression, with mosaic option.
Spatial Reference Information: Universal Transverse Mercator (UTM), North American Datum of 1983
