r.out.kde - GRASS GIS manual

Note: This document is for an older version of GRASS GIS that will be discontinued soon. You should upgrade, and read the current manual page.

NAME

r.out.kde - Exports raster with variable transparency into an image file

KEYWORDS

raster, kernel density, visualization, transparency, heatmap

SYNOPSIS

r.out.kde

r.out.kde --help

r.out.kde input=name background=name output=name [method=string] [--overwrite] [--help] [--verbose] [--quiet] [--ui]

Flags:

--overwrite: Allow output files to overwrite existing files
--help: Print usage summary
--verbose: Verbose module output
--quiet: Quiet module output
--ui: Force launching GUI dialog

Parameters:

input=name [required]: Raster map to be rendered with semi-transparency
background=name [required]: Background raster map
output=name [required]: Rendered output file
method=string: Method to scale transparency; Options: linear, logistic

DESCRIPTION
EXAMPLE
SEE ALSO
AUTHOR

DESCRIPTION

r.out.kde creates an image file (e.g., PNG, JPG, or GIF) where the input raster is rendered on top of background raster with varying transparency based on the values of the input raster. This can be used for example for visualization of kernel density estimate (KDE).

With logistic method, values are scaled so that lower values are more transparent and higher values are more opaque than with linear scaling.

This module requires Python Imaging Library (already required for GRASS GIS).

EXAMPLE

In this example, we visualize KDE of schools on top of shaded relief map.

g.region raster=elevation
# create background map
r.relief input=elevation output=relief
# compute kernel density estimate
v.kernel input=schools_wake output=schools_density radius=4000 multiplier=1000000
r.colors map=schools_density color=bcyr
r.out.kde input=schools_density background=relief method=logistic output=output.png