# BSL {landsat}

### Description

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

### Usage

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

### 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)

### 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.

### Values

- BSL
- Regression coefficients for the Bare Soil Line
- top
- band 3 and band 4 values for the full canopy point

### References

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

### Examples

Documentation reproduced from package landsat, version 1.0.8. License: GPL (>= 2)