Land cover was classified in a two-step process: unsupervised classification to define patch boundaries and spectral classes, followed by a supervised classification to assign cover type labels. TM bands 1 - 7, elevation, slope, and aspect attributes were used in the supervised classification. In all scenes, irrigated and non-irrigated agriculture, clouds, cloud shadow, urban areas, surface mines, and fires were manually labeled.
Parts of this grid were produced in four separate projects. Western Montana and northern Idaho were classified for the U.S. Forest Service, Region One, in a project (FSR1) completed in June 1996. The FSR1 project produced a separate riparian layer, unlike the other three projects where riparian vegetation was included in the overall supervised classification. This separate riparian grid was combined with the other FSR1 grids in order to match the later projects. The Little Missouri and Sheyenne National Grasslands were classified for the Custer National Forest as part of a project (CUSTER) completed in July 1997. The central Idaho project (CICP) was contracted by the U.S. Forest Service, Region Four, and was completed in August 1997. Finally, the eastern Montana project (EMT) was contracted by the Montana Department of Fish, Wildlife and Parks, and was completed in November 1997.
All individual grids within the state of Montana have undergone updates and standardization since the project completion dates in order to have as congruous a coverage throughout the state as possible. Cover types were combined and reduced to 50 types from a total of 94 for use with Gap Analysis. The grid was merged to a 2 ha minimum mapping unit (MMU) for upland cover types and a 90 meter MMU for riparian cover types. Cloud and cloud shadow were merged to 100 ha. Ground-truth data were provided by a variety of organizations for use in the classification process.
For more information, please refer to the project's final report: Redmond, R.L., M.M. Hart, J.C. Winne, W.A. Williams, P.C. Thornton, Z. Ma, C.M. Tobalske, M.M. Thornton, K.P. McLaughlin, T.P. Tady, F.B. Fisher, S.W. Running. 1998. The Montana Gap Analysis Project: final report. Unpublished report. Montana Cooperative Wildlife Research Unit, The University of Montana, Missoula. xiii + 136 pp. + appendices.
An atlas of land cover for the state also is available: Fisher, F.B., J.C. Winne, M.M. Thornton, T.P. Tady, Z. Ma, M.M. Hart, and R.L. Redmond. 1998. Montana land cover atlas. Unpublished report. Montana Cooperative Wildlife Research Unit, The University of Montana, Missoula. viii + 50 pp.
The following metadata elements are required by GAP, but do not parse using the FGDC ms parser (although similar elements can be found later in this document for several of these). For the convenience of GAP users, these elements are listed here. Data Set Identity: MTGAPVEG; Raster File Format: ARC/INFO GRID; Raster File Sensor: NA; Vector File Format: NA; Nonspatial File Format: NA; Source Distance Resolution: 90 meters; Raster File Number of Bytes per Pixel: 4; Native Data Structure: Raster.