I am trying to understand how to use multi-channel images (e.g. landsat or the land-cover data provided by Natural Earth). I am hoping that someone can confirm or correct my interpretation of the documentation at http://grasswiki.osgeo.org/wiki/LANDSAT and perhaps elaborate somewhat on the matter.
It appears that the appropriate module for importing multi-channel (RGB or RGBA) images is r.in.gdal. I was initially confused about why r.in.gdal split images into a raster map for each channel, but now I understand that a raster data is fundamentally a single channel of information and so the split is required if the image is to be treated as raster data. It follows then that displaying the image as a layer in a map requires re-assembling the channels, which can be accomplished with a module such as d.rgb.
I am still a little puzzled at why GRASS requires the seemingly complicated process of explicitly splitting and re-assembling the RGB channels of images. Does GRASS have some method that I haven't run across that simplifies this process to the two steps required in most other GIS software: 1) import image 2) display image as layer in map.