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Automatic computation of hot and cold pixels from Radiometric Surface Temperature (Ts)

Source: R/coldhotxy.R
coldhot.Rd

This function computes temperature coordinates of a hot and cold pixels based on only Surface Temperature. This function uses ranges of temperature.

Usage

coldhot(Tmin, Tmax, Ts = NULL, folder = NULL, welev = NULL)

# Default S3 method
coldhot(Tmin, Tmax, Ts = NULL, folder = NULL, welev = NULL)

Arguments

Tmin

Numeric. Minimum surface Temperature in map units (eg. Kilvin) that you want computation from. You can keep changing untill you get your desired values

Tmax

Numeric. Maximum surface Temperature in map units (eg. Kilvin) that you want computation from. You can keep changing untill you get your desired values

Ts

A RasterLayer data that indicates radiometric surface temperature values from remote sensing image, preferably in Kelvin (K). You can also point to raster file on your computer.

folder

An original directory of the images that contains all landsat 5,7 or 8 bands and metadata. At the moment only Landsat folder is supported

welev

Weather station elevation in meters

Value

Ts:

The selected or input Ts

Tshot:

The Temperature of hot pixel

Tscold:

The Temperature of cold pixel

xyhot:

combined x and y coordinates

candidates:

The similar candidates' pixels that can be used

Details

The function first divides the selected area into a number of clusters. The mean and standard deviations are computed. The cluster means with the lowest standard deviations and qualifying for upper (Ts) and lower (NDVI) limits (see above) are selected. The provided upper and lower probabilities are also used to select the final Ts.

References

Allen, R. G., Burnett, B., Kramber, W., Huntington, J., Kjaersgaard, J., Kilic, A., Kelly, C., & Trezza, R. 2013. Automated Calibration of the METRIC-Landsat Evapotranspiration Process. JAWRA Journal of the American Water Resources Association, 49(3): 563-576.

See also

coldTs, hotTs, coldTs2

Author

George Owusu

Examples

if (FALSE) { # \dontrun{
 folder=system.file("extdata","stack",package="sebkc")
  model=coldhot(Tmin=300,Tmax=310,folder=folder,welev=170)
  spplot(model$Tshot)
  spplot(model$Tscold)
  modauto=sebal(folder = folder,welev = 380,xycold=model$xycold,xyhot=model$xyhot)} # }