[GRASS-user] problem with vi.in.ogr

[Maciej Sieczka]

Jarek Jasiewicz wrote:

> Reasons found but problem exist:
> 
> 34 points has exactly the same coors. So topology cannot be bulid....

Jarek

Duplicate points should not make GRASS modules fail. Try this eg.:

# create 34 (like in your case) duplicate point vector:
i=0; while [ $i -ne 34 ]; do echo "100 100"; let "i++"; done |
v.in.ascii out=pt34 fs=" "

# export to shapefile
v.out.ogr input=pt34 type=point dsn=pt34 olayer=pt34

# import it back:
v.in.ogr dsn=$HOME/pt34/pt34.shp output=pt34_re
[...]
Importing map 34 features...
-----------------------------------------------------
Building topology ...
34 primitives registered
Building areas:  100%
0 areas built
0 isles built
Attaching islands:
Attaching centroids:  100%
Topology was built.
Number of nodes     :   1
Number of primitives:   34
Number of points    :   34
Number of lines     :   0
Number of boundaries:   0
Number of centroids :   0
Number of areas     :   0
Number of isles     :   0

All works - for me.

Maybe your shapefile is corrupted somehow? Can you send it for testing?

> location is set on EPSG 2174 (Polish 1965 zone 4)
> 
> when I try import shape with points to location:
> 
> v.in.ogr -o dsn=/home/jarekj/shp/PunktyAZP.shp output=azp min_area=0.0001 
> snap=-1 --overwrite 
> 
> I recive message:
> 
> No projection name! Projection parameters likely to be meaningless.

That's because GRASS doesn't know about the ESRIS's
Double_Stereographic - propably because GDAL and PROJ don't know it.
GDAL calls this projection "Oblique_Stereographic".

I have fed all the EPSG codes that use "+proj=sterea" (including EPSG
2174 from your case) into epsg_tr.py -wkt, and all they are parsed as
PROJECTION["Oblique_Stereographic"].

All the codes using "+proj=stere" are parsed as
PROJECTION["Polar_Stereographic"].

There are no traces of other Sterographic projections supported by
PROJ.4 (alsk, gall, gs48, gs50, lee_os, mil_os, ups) in my
/usr/local/share/proj/epsg.

According to [1] ESRI's Double_Stereographic is the same as GDAL's
Oblique_Steregraphic.

That would make sense. I have tried looking in the ESRI's resorces [2]
but haven't found a direct answer though.

Should Double_Stereographic be intepreted as Oblique_Steregraphic by
GRASS? Or is to be fixed in PROJ.4 or GDAL? Paul?

The are 18 EPSG codes using sterea. They all might result in same
problems in the GRASS - ESRI data exchange.

[1]
http://udig.refractions.net/docs/api-geotools/org/geotools/ct/proj/Stereographic.html
[2]
http://webhelp.esri.com/arcgisdesktop/9.2/index.cfm?TopicName=Double_Stereographic

Maciek