legend.whitening: Whitening legend (PNG)

In plotKML: Visualization of Spatial and Spatio-Temporal Objects in Google Earth

Whitening legend (PNG)

Description

Produces a PNG file that can be used in KML plots (visualization of uncertainty).

Usage

kml_legend.whitening(legend.res = 0.01, width = 120, height = 300, pointsize = 14, 
                 x.lim, e.lim, leg.asp = 0.3 *  width/height, 
                 legend.file = "whitening_legend.png",
                 matte = FALSE, png.type)

Arguments

legend.res	numeric; resolution on a 0-1 scale
width	integer; image width
height	integer; image height
pointsize	integer; point size in units for text
x.lim	numeric; upper and lower limits for target variable
e.lim	numeric; upper and lower limits for the normalized error
leg.asp	numeric; legend aspect
legend.file	character; output PNG file name
matte	logical; specify whether to fix transparency using ImageMagick
png.type	character; PNG type

Details

The output PNG file shows a 2D legend with values on the vertical axis and uncertainty on the horizontal axis. Whitening is only valid with Hue-Saturation-Intensity system where Hue's are used to represent values of the target variable, so that the amount of white color can be linearly used to represent uncertainty (i.e. whitening can not be used with different color palettes; or at least we do not recommend this).

Note

Google Earth does not properly handle a 24-bit PNG file which has a single transparent color. In order to force transparency in the output PNG, the function with try using ImageMagick convert function. ImageMagick needs to be installed separately and located using plotKML.env().

Author(s)

Tomislav Hengl

References

• Hengl, T., Heuvelink, G.M.B., Stein, A., (2004) A generic framework for spatial prediction of soil variables based on regression-kriging. Geoderma 122 (1-2): 75-93. doi: 10.1016/j.geoderma.2003.08.018

• Hengl, T., (2003) Visualisation of uncertainty using the HSI colour model: computations with colours. 7th International Conference on GeoComputation (CD-ROM), p. 8.

See Also

whitening

Examples

## Not run: # create the 2D legend for whitening (PNG file):
kml_legend.whitening(x.lim=c(5,20), e.lim=c(.6,1))

## End(Not run)

plotKML documentation built on June 7, 2022, 5:07 p.m.