projections and raster maps

Michael Hill mhill at
Sat Aug 28 17:32:32 EDT 1993

On Fri, 27 Aug 93 15:59:06 EST, Simon Cox wrote:

>What is the best way to change the projection of a raster layer (eg ll to
>I know that it can be done using the imagery functions, i.rectify, etc,
>with judicious intervention of m.ll2u, etc, on the POINTS file,
>but this seems like a crude instrument considering the equations are known!
>>From my brief scan of the manuals there is an [a-z].proj for everything except
>r ...
>Suggestions anyone?
>Simon Cox

I second this point from Simon. Why is there no r.proj. v.proj works 
nicely thankyou. But in a raster based GIS, surely r.proj is more 
important - perhaps it is more difficult.

Dragging cell data out to ascii files and running PROJ.4 over them to go 
from geog. to say, lcc, is a hell of a business. At present, it is easier 
to import grass rasters into ArcInfo (which we fortunately have), 
reproject, and take them back to grass. But that is also something of a 
convoluted business. Likewise using an imagery rectification is not 
something you want to do with hundreds of large rasters, which we and many 
others have.

I don't normally whinge like this - must be a bad mood, or Simon hitting a 
raw nerve!

Mike Hill

Michael J Hill
Research Scientist
CSIRO Pastoral Research Laboratory, Armidale, NSW, Australia,2350.
E-Mail address: mhill at chiswick.anprod.csiro.

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