File name or image file (matrix, data frame, or SpatialGridDataFrame) for Landsat band 3 DN (red).
band4
File name or image file (matrix, data frame, or SpatialGridDataFrame) for Landsat band 4 DN (NIR).
method
Either "quantile" or "minimum" – describes way in which soil line is identified.
ulimit
Upper limit for quantile of band ratios (ulimit < 1)
llimit
Lower limit for quantile of band ratios (llimit > 0)
Details
Finding the BSL requires identifying the lowest NIR values for each level of red. The quantile method takes the lowest set of points, those with a NIR/red ratio less than the llimit-th quantile. The minimum value method takes the lowest NIR value for each level of red. However they are found, these points with low NIR for their red values are used in a major axis regression to find the Bare Soil Line.
This function also identifies the full canopy point (maximum vegetation), by using the ulimit to identify the top points, with NIR/red ratio greater than the ulimit-th quantile, and with high NIR values. Red or NIR values of 255 (saturated sensor) are omitted when calculating the BSL.
Value
BSL
Regression coefficients for the Bare Soil Line
top
band 3 and band 4 values for the full canopy point
Author(s)
Sarah Goslee
References
Maas, S. J. & Rajan, N. 2010. Normalizing and converting image DC data using scatter plot matching. Remote Sensing 2:1644-1661.