ST_GeomFromGML crushes for Triangle (Triangulard Surface/TIN)

[itboyet]

I am trying to use the ST_GeomFromGML to insert some TIN/Triangular Object into Postgres database; however, PostGIS/PostgreSQL exits after I executed the following query:

SELECT ST_AsEWKT(ST_GeomFromGML(' <gml:TriangulatedSurface>

<gml:TrianglePatches>

<gml:Triangle>

<gml:exterior>

<gml:LinearRing gml:id="1">

<gml:posList srsDimension="3">

0 0 1000000 0 10 1000000 10 10 1000000 0 0 1000000

</gml:posList>

</gml:LinearRing>

</gml:exterior>

</gml:Triangle> <gml:Triangle>

<gml:exterior>

<gml:LinearRing gml:id="2">

<gml:posList srsDimension="3">

0 0 8000000 10 10 1000000 0 0 1000000 0 0 8000000

</gml:posList>

</gml:LinearRing>

</gml:exterior>

</gml:Triangle> <gml:Triangle>

<gml:exterior>

<gml:LinearRing gml:id="3">

<gml:posList srsDimension="3">

0 0 8000000 0 10 1000000 10 10 1000000 0 0 8000000

</gml:posList>

</gml:LinearRing>

</gml:exterior>

</gml:Triangle> <gml:Triangle>

<gml:exterior>

<gml:LinearRing gml:id="4">

<gml:posList srsDimension="3">

0 0 8000000 0 0 1000000 0 10 1000000 0 0 8000000

</gml:posList>

</gml:LinearRing>

</gml:exterior>

</gml:Triangle>

</gml:TrianglePatches>

</gml:TriangulatedSurface>'));

However, it would give me an actual error if I change the tag "TriangulatedSurface" to "TriangularSurface", which should not be the correct gml tag.

[pramsey]

Can you update your PostGIS to the latest revision? I am not seeing a crash here…

ERROR:  invalid GML representation

[pramsey]

select postgis_full_version();
                                                                          postgis_full_version                                                                           
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 POSTGIS="2.0.0alpha6SVN" GEOS="3.4.0dev-CAPI-1.8.0" PROJ="Rel. 4.7.1, 23 September 2009" LIBXML="2.7.8" SVN_REVISION=9229 USE_STATS

[colivier]

With TriangulatedSurface i got: TIN EMPTY

And with TriangularSurface ERROR: invalid GML representation

PostGIS trunk r9241

[pramsey]

I get the same. Pasteable version of the query:

SELECT ST_AsEWKT(ST_GeomFromGML('
<gml:TriangulatedSurface>
 <gml:TrianglePatches>
  <gml:Triangle>
   <gml:exterior>
    <gml:LinearRing gml:id="1">
     <gml:posList srsDimension="3">
      0 0 1000000 0 10 1000000 10 10 1000000 0 0 1000000
     </gml:posList>
    </gml:LinearRing>
   </gml:exterior>
  </gml:Triangle>
  <gml:Triangle>
   <gml:exterior>
    <gml:LinearRing gml:id="2">
     <gml:posList srsDimension="3">
      0 0 8000000 10 10 1000000 0 0 1000000 0 0 8000000
     </gml:posList>
    </gml:LinearRing>
   </gml:exterior>
  </gml:Triangle>
  <gml:Triangle>
   <gml:exterior>
    <gml:LinearRing gml:id="3">
     <gml:posList srsDimension="3">
      0 0 8000000 0 10 1000000 10 10 1000000 0 0 8000000
     </gml:posList>
    </gml:LinearRing>
   </gml:exterior>
  </gml:Triangle>
  <gml:Triangle>
   <gml:exterior>
    <gml:LinearRing gml:id="4">
     <gml:posList srsDimension="3">
      0 0 8000000 0 0 1000000 0 10 1000000 0 0 8000000
     </gml:posList>
    </gml:LinearRing>
   </gml:exterior>
  </gml:Triangle>
 </gml:TrianglePatches>
</gml:TriangulatedSurface>'));

[strk]

I see we have no cunit test for GML input, would be worth adding one (we could at least get a valgrind opinion on the matter)

[strk]

Comment here also suggests there are memory errors: source:trunk/postgis/lwgeom_in_gml.c#L654​ Time to move GML parser into liblwgeom ?

[strk]

I'm moving the code to liblwgeom…

[strk]

Oops, the gml parser includes reprojection which uses the PROJ cache, which in turn is only at the pgsql level…

[colivier]

@strk : there was previous reflexion related to moving it to liblwgeon here #444

I think there's 2 options right now:

• Check quickly that request posted by itboyet is valgrind clean

(so no need to play with proj4)

• tackle #444 for 2.0 rather than 2.1

I can spend some time on it, but i didn't plan (at all) to migrate the ~1000 units tests related to GeomFrom*ML to cunit syntax/logic.

[strk]

I've commented on #444, if you can spend some time checking itboyet case with valgrind that would be enough for me.

[strk]

I've noticed another thing: the library prints errors on stderr, like these:

namespace error : Namespace prefix gml on TriangulatedSurface is not defined
 <gml:TriangulatedSurface> <gml:TrianglePatches> <gml:Triangle> <gml:exterior> <
                         ^

it probably shouldn't.

Anyway the query runs valgrind-clean on a cassert-enabled postgresql 9.1

[strk]

I've dropped the POINTARRAY clone in r9279, still no memory errors I can see either on pgsql 9.1 or 8.4.

[itboyet]

I had version alpha5 when I had this error. I got "TIN EMPTY" after upgrading to alpha6. However, the GML has the correct format for insertion. Is it a bug since it returns "TIN EMPTY"?

[pramsey]

Well, it's a legal TIN (at least, the WKT version goes in fine) so the GML function should be looked at…

TIN(
((0 0 1000000,0 10 1000000,10 10 1000000,0 0 1000000)),
((0 0 8000000,10 10 1000000,0 0 1000000,0 0 8000000)),
((0 0 8000000,0 10 1000000,10 10 1000000,0 0 8000000)),
((0 0 8000000,0 0 1000000,0 10 1000000,0 0 8000000))
)

[itboyet]

Meanwhile, as a remark I also want to point out that ST_AsGML does not support TIN and/or Triangle Geometry. Perhaps it would be great to have both INPUT function (ST_GeomFromGML) and OUTPUT function (ST_AsGML) working in sync.

[pramsey]

Yes, that would be far easier, I can just remove the FromGML support!

[pramsey]

So, turns out GML is case sensitive… this works

SELECT ST_AsEWKT(ST_GeomFromGML('
<gml:TriangulatedSurface>
 <gml:trianglePatches>
  <gml:Triangle>
   <gml:exterior>
    <gml:LinearRing gml:id="1">
     <gml:posList srsDimension="3">
      0 0 1000000 0 10 1000000 10 10 1000000 0 0 1000000
     </gml:posList>
    </gml:LinearRing>
   </gml:exterior>
  </gml:Triangle>
  <gml:Triangle>
   <gml:exterior>
    <gml:LinearRing gml:id="2">
     <gml:posList srsDimension="3">
      0 0 8000000 10 10 1000000 0 0 1000000 0 0 8000000
     </gml:posList>
    </gml:LinearRing>
   </gml:exterior>
  </gml:Triangle>
  <gml:Triangle>
   <gml:exterior>
    <gml:LinearRing gml:id="3">
     <gml:posList srsDimension="3">
      0 0 8000000 0 10 1000000 10 10 1000000 0 0 8000000
     </gml:posList>
    </gml:LinearRing>
   </gml:exterior>
  </gml:Triangle>
  <gml:Triangle>
   <gml:exterior>
    <gml:LinearRing gml:id="4">
     <gml:posList srsDimension="3">
      0 0 8000000 0 0 1000000 0 10 1000000 0 0 8000000
     </gml:posList>
    </gml:LinearRing>
   </gml:exterior>
  </gml:Triangle>
 </gml:trianglePatches>
</gml:TriangulatedSurface>'));

[pramsey]

And, incidentally, As_GML does support TIN, just for GML3 only:

select st_asgml(3,'TIN(((0 0 1000000,0 10 1000000,10 10 1000000,0 0 1000000)),((0 0 8000000,10 10 1000000,0 0 1000000,0 0 8000000)),((0 0 8000000,0 10 1000000,10 10 1000000,0 0 8000000)),((0 0 8000000,0 0 1000000,0 10 1000000,0 0 8000000)))'::geometry);

and the full wrap-around

select st_astext(st_geomfromGML(st_asgml(3,'TIN(((0 0 1000000,0 10 1000000,10 10 1000000,0 0 1000000)),((0 0 8000000,10 10 1000000,0 0 1000000,0 0 8000000)),((0 0 8000000,0 10 1000000,10 10 1000000,0 0 8000000)),((0 0 8000000,0 0 1000000,0 10 1000000,0 0 8000000)))'::geometry)));

[pramsey]

There, final answer, the error message from TIN→GML2 is now more useful at r9331.

[colivier]

For the record GML 2 don't handle TIN or PolyhedralSurface…