On Tuesday 07 October 2008, Frank Warmerdam wrote: > Dylan Beaudette wrote: > > Hi, > > > > I am not sure if this is a DBF issue, or something deeper in OGR, but > > there does not appear to be a mechanism for preserving 'nodata' or NULL > > values when exporting from GRASS to vector formats through v.out.ogr. > > ... > > > It seems that on export via OGR there is some kind of mangline of nodata. > > This issue is a serious problem anytime you need to move vector data > > between applications, through the use of an intermediate file (usually a > > shapefile). > > > > Any ideas on what could be causing this problem? Fixing it would solve > > several important issues. If need be I will file a new ticket on the > > topic. > > > > Relevent tickets? > > http://trac.osgeo.org/gdal/ticket/809 > > http://trac.osgeo.org/gdal/ticket/528 > > Dylan, > > Generally speaking OGR understands about null attribute values, though > there may be no way to represent them in some formats. They should work > fine in shapefile format though. > > Reviewing the mk_att() function in v.out.ogr's main.c I don't see > any effort to distinguish between null and non-null attributes so > I think the problem is just a limitation of v.out.ogr. If possible, > I'd suggest fixing it there. > > Best regards,
Thanks a lot Frank. You never fail to impress when it comes to finding bugs! I will follow this up over on the GRASS-dev list. Cheers, Dylan -- Dylan Beaudette Soil Resource Laboratory http://casoilresource.lawr.ucdavis.edu/ University of California at Davis 530.754.7341 _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
