Digital Orthoimagery

Aerial and satellite imagery, in the form of digital orthoimagery, is the foundation for most public and private GIS systems (NSGIC, Digital Imagery for the Nation, 2006).

Aerial Imagery - A photograph of the earth's surface taken from a platform flying above the surface but not in orbit, usually an aircraft. Aerial photography is often used as a cartographic data source for base-mapping, locating geographic features, and interpreting environmental conditions.

Orthophotograph - An aerial photograph from which distortions owing to camera tilt and ground relief have been removed. An orthophotograph has the same scale throughout and can be used as a map.

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Status of Framework

NEW - FY2011 Draft Imagery Business Plan is Available

The most recent statewide orthoimagery is the 2009 National Agricultural Imagery Program (NAIP) dataset. The 1 meter ground sample distance (GSD) ortho images were rectified to a horizontal accuracy of within +/- 5 meters of reference digital ortho quarter quads (DOQQs) from the National Digital Ortho Program (NDOP). NAIP imagery may contain as much as 10% cloud cover per tile.

The data were provided by the U.S. Farm Services Agency National Agricultural Imagery Program to the State of Montana as multispectral 4-band GeoTIFF files tiled as 3.75' x 3.75' quarter quadrangles formatted to the UTM coordinate system using NAD83. The data are available as web services from the BMSC or as downloadable natural-color Compressed County Mosaics (CCMs) from the Montana State Library.

The Montana Base Map Service Center (BMSC) web services are provided in Montana State Plane coordinates. Services available include: ArcGIS Server Image services, Open Geospatial Consortium, Inc. (OGC) web coverage services (WCS), and OGC web map services (WMS). The image and web coverage services provide users direct access to the native GeoTIFF files and pixel data for geoprocessing and image analysis.

The original GeoTIFF files are available by request from the BMSC.

An ESRI shapefile of the DOQQ grid along with the dates the images were collected is available on the data page.