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2 Query of raster cell values and metadata

In order to get coordinates and raster attributes of individual pixels the module d.what.rast can be run after displaying the raster map:

d.what.rast

It is also possible to query multiple rastermaps that have not been displayed:

d.what.rast map=elevation.dem,geology,soils

By clicking on a pixel with the mouse its characteristic values are displayed in the terminal window. Also the attribute values of a pixel can be queried in several maps displayed in the monitor. Exit the module by clicking the right mouse button.

r.info

The r.info module is used for displaying basic information and metadata information for the rastermap. It also shows a data description, data type, the map projection, and the value ranges of available categories.

r.info landuse
r.info -r landuse

r.cats

To control the attributes of a rastermap, create a table with assigned label numbers and appropriate text attributes using the r.cats module:

r.cats map=landuse
1       residential
2       commercial and services
3       industrial
4       other urban
5       reservoirs
6       bare exposed rock
7       quarries, strip mines and gravel pits
8       transportation and utilities

r.report

To determine the area of individual geological units in the Spearfish region, for example, use the r.report module as shown below (also see r.stats). This module calculates statistics based on the current region and raster resolution settings. Therefore, zooming in prior to executing this command will describe the cutout region only:

g.region rast=geology -p
r.report -h geology units=h
+---------------------------------------------------------------------+
|                      Category Information                |          |
|#|description                                             |  hectares|
|---------------------------------------------------------------------|
|1|metamorphic. . . . . . . . . . . . . . . . . . . . . . .|  1051.000|
|2|transition . . . . . . . . . . . . . . . . . . . . . . .|    13.000|
|3|igneous. . . . . . . . . . . . . . . . . . . . . . . . .|  3285.000|
|4|sandstone. . . . . . . . . . . . . . . . . . . . . . . .|  6755.000|
|5|limestone. . . . . . . . . . . . . . . . . . . . . . . .|  5537.000|
|6|shale. . . . . . . . . . . . . . . . . . . . . . . . . .|  4170.000|
|7|sandy shale. . . . . . . . . . . . . . . . . . . . . . .|  1019.000|
|8|claysand . . . . . . . . . . . . . . . . . . . . . . . .|  1307.000|
|9|sand . . . . . . . . . . . . . . . . . . . . . . . . . .|  3295.000|
|*|no data. . . . . . . . . . . . . . . . . . . . . . . . .|   168.000|
|---------------------------------------------------------------------|
|TOTAL                                                     |26,600.000|
+---------------------------------------------------------------------+

r.timestamp

For processing time series it is often necessary to provide maps with a timestamp (time of creation, data acquisition, and so on). For this purpose the module r.timestamp is used. Absolute and relative dates can be indicated, which are stored independently from the file history:

r.timestamp landuse date="27 Sep 2003"
r.timestamp landuse date="27 Sep 2003/20 Feb 2004"

A more detailed description of the available timestamp formats can be found in the help file via g.manual r.timestamp.