[GRASS5] difficulties with r.proj

Frank Warmerdam warmerdam at pobox.com
Mon Oct 29 12:11:15 EST 2001

Andreas Lange wrote:

>>So, it looks like g.setproj needs to be fixed to prompt to change the
>>ellipsoid if the current one is invalid.
> r.in.gdal needs to be fixed to read the ellipsoid from
> $GISBASE/etc/ellipse.table. 


As I understand it the ellipse name is irrelevant as long as the ellipse
parameters are correct in the definition.  Certainly that is the case with
the get_proj.c code that passes the definition to PROJ.4.  It just drops
the ellps= setting as long as their are parameter definitions.

The ellipse.table file does have clark66 but PROJ.4 knows the same ellipsoid
as clrk66.  The r.in.gdal code is based on essentially generating PROJ.4
definitions for the PROJ_INFO file.

Do you know of aspects of GRASS which require the ellipse name in the
PROJ_INFO file to match an ellipse name in the ellipse.table file exactly?

In GRASS 5.1 I would like to have the PROJ_INFO file work for any acceptable
PROJ.4 definition with some hacks to ensure older style PROJ_INFO files
continue to work properly.  The subtle set of differences between PROJ.4
and GRASS coordinate system definitions is (certainly in my case) a source
of bugs and confusion.

Best regards,

I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent

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