[GRASSLIST:930] RE: interpolation & shading problem/question
John Gillette
JGillette at rfmd.com
Fri Aug 8 13:58:30 EDT 2003
> The file mandes_.LI comprises N X Y Z values, where N is a
> record ID that
> I'm omitting when I build the site file. The Z value is depth in
> meters, X & Y are long/latitude in decimal degrees.
>
...
>
> shade.rel.sh altitude=20 azimuth=270 elevation=andes5m
>
>
shade.rel.sh takes a numerical derivative. Your x,y location
is in degrees but your z data is in meters.
Does this cause the problem? Do you need to re-project the data
to a meters coordinate system and then do the shading? Or perhaps
change the equations in shade.rel.sh to scale the derivative correctly?
Looking at the equations, x and y are divided by 8 * ewres() or 8 * nsres().
I don't know the answer. Perhaps someone knows the answer to this?
John
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