using sites to re-categorise rasters and polygons

Michael Hill mhill at []
Thu Nov 25 11:34:13 EST 1993


I have used the "thiessen" routine in ArcInfo to create polygons centred on 
my site data (because s.voronoi does not work!)and imported the thiessen 
polygons back into Grass4.1 (by rasterising in ArcInfo and bringing in an 
ascii grid, because Grass ALWAYS fails to "make" the point to area 
conversion required to label polygons for a percentage of the polygons, and 
I have LOTS!).


What I have is a raster which has values which correspond to a site list 
for areas corresponding to the thiessen polygons. But, I have a site 
database with 100 attributes, and I want to allocate the various site 
variables to the corresponding raster locations for all of these variables.

How can I do this smoothly in Grass4.1? In ArcInfo, the polygon coverage 
can be changed simply by using "get sites" in ArcEdit, thus allowing the 
polygon categories to be changed and new map layers created corresponding 
to each site variable.

I figure there must be a simple way, except that I'm too thick with C, 
scripts, etc to work it out. It could be done manually with some editing 
and fiddling with output from, BUT, I hope there is an easier, dare 
I say it, more elegant, solution.

By the way, nobody has piped up with a solution to my monitor problem, 
broadcast to the list last week. In brief, no text is returned in menus on 
the monitor, since upgrade 1 was installed. I use d.zoom etc from memory. 
Any clues?

Michael Hill

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

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