ms_shapeObjFromWkt doesn't work with MULTILINESTRING and MULTIPOLYGON

[maikstoeckmann@…]

The PHP mapscript function ms_shapeObjFromWkt doesn't work with MULTILINESTRING 
and MULTIPOLYGON. For these geometry types the function generally returns 
nothing. No error message is produced.

[dmorissette]

MapServer doesn't do the parsing of WKT, it relies on methods from GEOS (if
available) or from OGR (if GEOS not available) to do the conversion from WKT.

We'd need to know the version of GEOS (if you have it) and OGR that you are using.

[maikstoeckmann@…]

I compiled mapserver with OGR option only. My DGAL/OGR-Version was 2.0.33-1.1. 
I have tried to install GEOS 2.2.3, but then I get an Internal Server Error 
message, when using the ms_shapeObjFromWkt function.

[sdlime]

Can you share the WKT strings? GEOS support was re-written in 4.10 and should 
be much more robust. I'll take a look against 4.8 though but need your test 
case.

Steve

[maikstoeckmann@…]

Sorry, my version info wasn't correct. So again. I'm using:
MapServer/MapScript 4.8.4,
GDAL/OGR 1.3.2,
I compiled MapServer completely without GEOS, but with GDAL/OGR 1.3.2. The 
mapscript function ms_shapeObjFromWkt works very well, except for multipart 
geometries.
Should I have to use GEOS? What version?

[dmorissette]

Short answer: it seems that the OGR implementation doesn't support
multilinestring and multipolygon. Hopefully the GEOS implementation does but I
didn't check.

Long answer:

After a quick check in mapogr.cpp, it seems that msOGRGeometryToShape() only
supports wkbPoint, wkbLineString and wkbPolygon. However, it seems that the
underlying ogrGeomLine() function should be able to handle wkbMultiLineString
and wkbMultiPolygon as well.

Question for Frank: did you intentionally omit wkbMultiLineString and
wkbMultiPolygon in msOGRGeometryToShape() because of a know limitation of the
underlying OGR_G_CreateFromWkt() or some other reason?

[sdlime]

The GEOS version does implement multipart features... I've tested with simple 
multipart polygons but not multi linestrings. However, multiline strings are 
*much* easier since you don't have to deal with inner/outer rings.

Steve

[maikstoeckmann@…]

I modified the function in maporg.cpp for my own, re-compiled mapscript and now 
it works fine!

int msOGRGeometryToShape(OGRGeometryH hGeometry, shapeObj *psShape,
                         OGRwkbGeometryType nType)
{
    if (hGeometry && psShape && nType > 0)
    {
        if (nType == wkbPoint)
          return ogrConvertGeometry((OGRGeometry *)hGeometry,
                                    psShape,  MS_LAYER_POINT);
        else if (nType == wkbLineString || nType == wkbMultiLineString )
          return ogrConvertGeometry((OGRGeometry *)hGeometry,
                                    psShape,  MS_LAYER_LINE);
        else if (nType == wkbPolygon || nType == wkbMultiPolygon)
          return ogrConvertGeometry((OGRGeometry *)hGeometry,
                                    psShape,  MS_LAYER_POLYGON);
        else
            return MS_FAILURE;
    }
    else
        return MS_FAILURE;
}

[dmorissette]

Frank, can you please confirm that it would be safe to apply Maik's change to
msOGRGeometryToShape() in 4.10?
(That fix seems fine to me as long as there is no known limitation in OGR's
OGR_G_CreateFromWkt() that I'm not aware of.)

[fwarmerdam]

The proposed changes look fine to me. 

[dmorissette]

Sounds good. Applying this fix in 4.10 CVS now.

[dmorissette]

Applied Maik's fix in CVS HEAD. Will be in 4.10.0-beta3.


P.S. I just saw in CVS logs that msOGRGeometryToShape() was created by Assefa,
not Frank. Sorry for bugging you about this one Frank, I thought it had been
created by you.

[fwarmerdam]

I have also added MULTIPOINT support, and added tests for these three
multi geometries in msautotest/misc/ogr_wkt.map. 

[fwarmerdam]

This bug is also somewhat related to Bug 1618 which relates to going the other
way.