d.region.grid - 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

d.region.grid - Drapes a color raster over an shaded relief or aspect map.

KEYWORDS

display, elevation, relief, hillshade, visualization

SYNOPSIS

d.region.grid

d.region.grid --help

d.region.grid [-r] [region=name] [raster=name] [color=name] [width=float] [--help] [--verbose] [--quiet] [--ui]

Flags:

-r: Use the current computation region; This will not work in cases when region is handled in a special way such as GUI
--help: Print usage summary
--verbose: Verbose module output
--quiet: Quiet module output
--ui: Force launching GUI dialog

Parameters:

region=name: Use an existing saved region
raster=name: Use a raster map
color=name: Color; Grid color; Default: gray
width=float: Grid line width

DESCRIPTION
EXAMPLES
NOTES
SEE ALSO
AUTHOR

DESCRIPTION

d.region.grid plots a grid defined by the computational region or by a raster map. The computational region can be the current computational region or a saved computational region.

To compare how grids (resolutions) of two rasters align, here a digital elevation model and a Landsat image, you can zoom to an area of interest and show grids of both rasters. First, zoom close enough that the raster cells become visible. Here a small saved region is used and a negative value for grow causes g.region to zoom-in even more:

g.region region=rural_1m grow=-250 -p

Start a monitor (skip this in the GUI):

d.mon start=cairo width=600 height=400 output=two_rasters.png

Optionally, show the digital elevation model and its shaded relief raster:

d.shade shade=elevation_shade color=elevation

Add grid for the elevation raster using a subtle color:

d.region.grid raster=elevation color="#9B520D"

Add grid for the Landsat raster using a high-contrast color:

d.region.grid raster=lsat7_2002_10 color=black

Figure: Grids of two rasters which are not aligned

If you are using d.mon, you can stop the monitor using:

d.mon stop=cairo

Showing the current computational region grid

Let's say you want to render grid cells of a computational region you plan to resample a raster map into. First, set the computational region to the raster map, then start the monitor (here we use file-based rendering in the command line with the cairo driver), and finally, render the raster map:

g.region raster=elevation
d.mon start=cairo width=600 height=400 output=new_region_grid.png
d.rast map=elevation

Then change to the desired computational region, here the new region resolution is set to 1000 meters (map units) and fitted into the current region extent without modifying the 1000 meters value.

g.region res=1000 -a

Now, you are ready to plot the grid of the current computational region:

d.region.grid -r

Figure: Raster with resolution 10 meters and grid of a computational region with resolution 1000 meters

Assuming you used d.mon to start rendering as in the code above, you can stop it using:

d.mon stop=cairo

Using an existing saved region

Displaying a saved computational region is extremely helpful in GUI, were you save the current region first:

g.region save=study_area

Then, you use Add command layer to add the following command:

d.region.grid region=study_area

NOTES

Use through the Add command layer option in the GUI.
In the GUI, it is currently not possible to directly draw the current region.
Generally, only the grid resolution is based on the selected region or raster, with extent of the grid being limited only by what is being displayed (this happens to be the current computational region when rendering directly to files in command line).

AUTHOR

Vaclav Petras, NCSU GeoForAll Lab

SOURCE CODE

Available at: d.region.grid source code (history)

Latest change: Wednesday Feb 02 21:46:15 2022 in commit: 2e3dcb5eafe36d640aa68585be0192f07ca1eabb