BSL {landsat}

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)

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.

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.

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)