[GRASSLIST:4913] Re: Problems with importing polar data
glynn.clements at virgin.net
Fri Nov 8 21:53:57 EST 2002
Anton B. Ivanov wrote:
> I am new to the GRASS program and it seems to be VERY powerful. However,
> I have been a little frustrated trying to import my polar data into it.
> Here's a problem : I have data (images) projected into a polar
> stereographic projection (using some camera speicific software). I import
> them using r.in.bin and set up proper lat/lon bounds for these images. The
> projection setup is as ups (see PROJ_INFO file below).
> However, when I'm trying display data, put a grid on it or make a
> postscript map, the output projection look like a simple cylindrical or
Is the data which you imported really in UPS, and not Lat/Lon?
> How do I tell GRASS to display my data in polar stereographic projection
> and overlay grid on it?
GRASS displays data "as is"; none of the display commands will attempt
to project it. The *only* commands which project data are r.proj,
v.proj and s.proj. Most of the other commands simply work with
arbitrary X/Y coordinates, without any consideration as to what those
coordinates actually represent (apart from a few commands which take
account of the units, e.g. feet/metres).
> Another problem is to project data from simple cylindrical projection
> into polar stereographic (using r.proj) . I have no luck there either.
If you have Lat/Lon data, import it into a Lat/Lon location. Then
create a UPS location, and run r.proj from that location.
> Any help will be highly appereciated!!!!
> Thanks a lot in advance
> Anton Ivanov
> PS. here's PROJ_INFO and PROJ_UNITS pair for my location. I work with
> Martian data, so geoid is that of Mars and no datum has been specified.
> name: Universal Polar Stereographic
> proj: ups
Again, is the data which you are importing really in UPS? The GRASS
import utilities don't perform any projection of the data; you have to
import it into a location whose projection matches the data.
Glynn Clements <glynn.clements at virgin.net>
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