[Qgis-user] averaging raster grid

[Micha Silver]

M.E.Dodd wrote:

> See replies to each point:
> "* Display the GRASS region - you should see the red rectangle - then 
> verify that the vector and raster layers are within that region (again 
> from their info tables)." 
> Does the whole of each layer have to be within the red rectangle?  It certainly was not when I started as I had not considered this.  However in the large numbers of things I later tried I set the area of interest to be the whole world which did include all layers but still got same 
Wait a sec. The whole world? At what resolution?? You might have a 
region so large it would take many GB of memory to do anything...
> problems.  Setting this area is rather a pain using the current method of typing numbers into the boxes, it would be nicer to have the option of drawing the rectangle directly on the map.
>   
Actually you can. In QGIS, click the Edit GRASS Region button, then drag 
the mouse over the area you want to define as the current region, Double 
click to end and accept the new region. You should see the new extents 
in the GRASS region window, and the red rectangle should appear 
enclosing only the new region.
 
> "* In the Raster->Properties->Symbology, switch to a "pseudocolor" color 
> ramp. (Maybe the whole range is being displayed as white, for some reason?" Don't think this is the problem as I tried altering various things and nothing made the map show up.
>
> "* Are all the layers, raster and vector, in the same GRASS location and 
> mapset?"  
> This is what I thought was the problem but could not work out how to get them all into the same mapset, they (the vector and rasters) are in separate ones.
>   
If you have the patience, why not make a new mapset, within your WGS84 
Location. Then import into that mapset just one raster, and set the 
default region to just that raster. Now clip a section of the vector 
grid to cover just that region, and import it. Then try to go from there.