[GRASS5] krass/krassovsky

[Helena Mitasova]

well, not long ago GRASS was not dependent on PROJ.4
and  there are many users who have years of grass databases that were
created before PROJ.4 and before there were standards for documentation
about projections. So while I agree that it would be great if PROJ_INFO 
followed
PROJ.4 I would also like to have a program that would automatically 
convert
my old PROJ_INFO to the new standardized form.
So the changes you are suggesting below may require a little bit more
work and may create quite a bit of hassle for old users (who may not 
even use cs2cs
or gdalwrap, so they may not care about its syntax), but they sure 
would be nice
if somebody can commit time to do it,

Helena


On Nov 28, 2005, at 2:33 PM, Maciek Sieczka wrote:

> Dear developers,
>
> Sevaral questions and complaints:
>
> 1. Does Grass need to have it's own names for ellipsoids? PROJ.4 for
> Krassovsky uses "krass". Grass doesn't recognize it and requires
> "krassovsky".
>
> 2. When creating a location from EPSG code in Grass, instead of
> ellipsoids names "a" and "es" are used. Using ellipsoids names would
> make PROJ_INFO less obscure.
>
> 3. Why does Grass recognize both GRS80 and grs80 (as well as gRs80 and
> other mutations)? PROJ.4 demands GRS80 strictly.
>
> 4. Creating a PROJ_INFO form ESPG:2180 inserts a "datum: etrs89" line.
> For what purpose? Wouldn't it better and conformal with PROJ.4 to use
> towgs84: 0,0,0 simply? PROJ.4 doesn't even know what "etrs89" is.
>
> 5. Beginners I talk about PROJ.4 to find it hard to understand why
> Grass, being dependant on PROJ.4 for handling coordinate systems,
> doesn't fully follow it's convention and complicates issues complicated
> enough. I agree with them - once I learn the correct syntax for a
> projection definition to use with  cs2cs or gdalwarp I have to learn it
> once more for Grass.
>
> 6. What's worse, PROJ_INFO actually follows PROJ.4 convention in some
> aspects, but in other it doesn't. This is confussing - eg. once I learn
> "tmerc" means the same for PROJ.4 and Grass I start suspecting that eg.
> ellipsoids will be handled the same way. And it seems to be true for
> some time, until this assumption fails for Krassovsky.
>
> All these make teaching PROJ.4 and Grass more complicated than needed.
> Anybody thinks the same? Opposite?
>
> Maciek
>
>
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Helena Mitasova
Dept. of Marine, Earth and Atm. Sciences
1125 Jordan Hall, NCSU Box 8208,
Raleigh NC 27695
http://skagit.meas.ncsu.edu/~helena/