projections and raster maps

[Michael Hill]

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
>utm).
>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?
>
>Thanks
>
>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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I have a crude version of r.proj that works just like v.proj, if there is enough
interest I will put it in moon.

Srinivasan