landsat (version 1.1.2)

BSL: Bare Soil Line

Description

Finds Bare Soil Line (BSL) and maximum vegetation point.

Usage

BSL(band3, band4, method = "quantile", ulimit = 0.99, llimit = 0.005, maxval = 255)

Value

BSL

Regression coefficients for the Bare Soil Line

top

band 3 and band 4 values for the full canopy point

Arguments

band3

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).

maxval

Maximum value for band data; default of 255 for Landsat 5 and 7.

Author

Sarah Goslee

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.

References

Maas, S. J. & Rajan, N. 2010. Normalizing and converting image DC data using scatter plot matching. Remote Sensing 2:1644-1661.

Examples

	data(nov3)
	data(nov4)
	nov.bsl <- BSL(nov3, nov4)
	plot(as.vector(as.matrix(nov3)), as.vector(as.matrix(nov4)))
	abline(nov.bsl$BSL, col="red")
	points(nov.bsl$top[1], nov.bsl$top[2], col="green", cex=2, pch=16)