[GRASS-user] raster with multiple attributs

Glynn Clements glynn at gclements.plus.com
Fri Oct 20 11:33:34 EDT 2006

Michaël Rabotin wrote:

> Hi everybody, a newbie question:
> for the raster in GRASS, is it possible to have for each pixel several
> attributs or is it limited to one attribut (cat) per pixel ?

Each cell has a single value (category), which can be associated with
a single attribute.

However, you can create "reclass" maps which share the same underlying
raster data but with the categories remapped (you can use an identity
mapping if you only want to change the categories' attributes).

Reclass maps are essentially "views" of an existing map.

A reclass map can have its own category attributes, colour table, etc. 
Reclass maps typically require significantly less storage than normal
raster maps. If you replace the base map, any reclass maps which are
based upon will be updated automatically (a reclass map just consists
of the name of the base map and a list of category mappings).

E.g. in the Spearfish sample data set, the soil.br.depth,
soils.Tfactor, soils.ph, soils.range and texture maps are all reclass
maps based upon the soils map.

Glynn Clements <glynn at gclements.plus.com>

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