DISTINGUISHING VEGETATION FROM SOIL BACKGROUND INFORMATION

Landsat-1 and -2 multispectral scanner (MSS) data from six overpass dates (April 2, May 17, June 4, July 10, October 17, and December 10, 1975) showed that MSS digital data for bare soil, cloud tops, and cloud shadows followed a highly predictable linear relaton (soil background line) for MSS bands 5 and 7 and bands 5 and 6. Increasing vegetation development, documented by leaf area index (LAI) measurements, of 1973 and 1975 grain sorghum crops, was associated with displacement of sorghum MSS digital counts perpendicularly away from the soil background line. Consequently, the perpendicular distance of a sorghum MSS measurement from the soil background line was tested as an index of plant vegetative develoment. Two perpendicular vegetation index models, the PVI and PVI6, yielded significant coefficients of determination of 0.659, respectively, with LAI. Coefficients of determination for a transformed vegetation index (TV16) and a green vegetation index (GVI) that have been used by others were 0.531 and 0.653, respectively, for the same data set. The PVI technique permits the calcualtion of the coordinates of the intersection of the vegetation and soil background lines; hence, it gives the position of a given pixel on the soil background line that other vegetation indexes do not. Since position along the soil background line should vary with soil water content, soil crusting, and crop shadows, the possibility of deducing information about soil surface conditions becomes apparent. The Landsat data space surrounding the soil background line for MSS5 and MSS7 was divided into ten decision regions corresponding the water; cloud shadow; low, medium, and high reflecting soil; cloud tops; low, medium, and dense plant cover; and a region (threshold) into which no Landsat data are expected to fall. It was demonstrated that, by using a table lookup procedure and printer symbols for each decision region, Landsat study areas or scenes could be gray mapped to meaningfully display vegetation density and soil condition categories without prior knowledge of local crop and soil conditions. /Author/

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    American Society of Photogrammetry

    105 North Virginia Avenue
    Falls Church, VA  USA  22046
  • Authors:
    • Richardson, A J
    • Weigand, C L
  • Publication Date: 1977-12

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  • Accession Number: 00168424
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Feb 16 1978 12:00AM