[postgis-users] server crash on st_transform, st_buffer and a few questions concerning projections

[erik]

Dear list,

1) I just provoked a postgres crash while performing the following query on
my postgis database:

select st_transform(the_geom,32768) from polygons;

The projection of the original dataset is 32767. The destination proj is
32768. As a general rule I'm having trouble working with this last with open
source software (uDig, postgis, ogr - all of these don't transform from this
proj correctly) and Google doesn't give much help. This is the standard EU
projection. Anybody have experience with this?

Entries in spatial_ref_sys:
32767;"";;"PROJCS["Belge_Lambert_1972",GEOGCS["GCS_Belge_1972",DATUM["Reseau_National_Belge_1972",SPHEROID["International_1924",6378388.0,297.0]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Lambert_Conformal_Conic_2SP"],PARAMETER["False_Easting",150000.01256],PARAMETER["False_Northing",5400088.4378],PARAMETER["Central_Meridian",4.367486666666666],PARAMETER["Standard_Parallel_1",49.8333339],PARAMETER["Standard_Parallel_2",51.16666733333333],PARAMETER["Latitude_Of_Origin",90.0],UNIT["Meter",1.0]]";"+proj=lcc
+lat_1=49.8333339 +lat_2=51.16666733333333 +lat_0=90
+lon_0=4.367486666666666 +x_0=150000.01256 +y_0=5400088.4378 +ellps=intl
+units=m +no_defs "

32768;"";;"PROJCS["ETRS_1989_LAEA",GEOGCS["GCS_ETRS_1989",DATUM["D_ETRS_1989",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Lambert_Azimuthal_Equal_Area"],PARAMETER["False_Easting",4321000.0],PARAMETER["False_Northing",3210000.0],PARAMETER["Central_Meridian",10.0],PARAMETER["Latitude_Of_Origin",52.0],UNIT["Meter",1.0]]";""

2) I also crash postgres on st_buffer(the_geom,0.0).
3) Do you know of any standard way of correcting selfintersecting polygons?
I've tried to correct them with st_simplify and st_buffer(the_geom,0.001).
The first doesn't work, the last works somewhat but still crashes the server
on some polygons. ArcView manages these seamslessy but I don't want to
depend on ArcView for all kind of reasons.
4) Does anyone know of a good general book on GIS, projections, etc? i've
been working on GIS for a while now, but I still feel like a noob on all the
theoretical stuff and I get the impression I'm not progressing enough just
with Google and by encountering problems "on the fly".

Any suggestions welcome.
Erik
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