Vegetation reflectance plays as a noise source in extracting soil information from vegetated area. In this paper, a simple optical model which explained the influence of vegetation reflectance on soil reflectance is proposed and the soil index which represents soil types independent of vegetation cover, is described.
This soil index is considered to be sensitive to the degree of the soil organic matter content. The usefulness of this soil index was investigated and tested by the channel selection based on the statistical distances among soil classes and by multispectral apttern recognition.
As a result, by combining the SI-value with other 3-channel which represent vegetation reflectances, various types of soil with 0-50 % vegetation covers are accurately classified.