Le vendredi 02 mai 2014 20:59:58, Ochs, Elke ERDC-RDE-CRREL-NH a écrit :
> Hello,
>
> I'm not able to save a spatial reference to a GML file and would like help
> understanding why. I'm creating a new GML from a copied feature. I
> assign the spatial reference to both the output layer and geometry.
> During debug, the layer and geometry report that the SR has been assigned
> correctly (GetSratialRef/GetSpatialReference). When I open the result GML
> file in another script, the spatial reference is empty.
Well, this is tricky :
- SRS in GML are only supported as EPSG codes. So you cannot pass an arbitrary
proj.4 string
- Even if you do so, you will find that reading back the file will not lead to
a
SRS to be retrieved, since the driver is conservative by default (a GML file
could have a mix of various SRS and we cannot trust the first one found in the
file).
>
> It's a non-standard SRS (albers, units feet) - not sure if this is an
> issue.
>
> I'm using GDAL 1.10 compiled with Expat. I'm fairly new to all of this.
> Any help is appreciated. I'm including most of the script, b/c I'm not
> sure where my error might be. Some of it is taken from the GDAL/OGR
> Cookbook.
>
> drv = ogr.GetDriverByName("GML")
> ds = drv.Open(gmlin,0)
>
> srs = osr.SpatialReference()
> proj4str = "+proj=aea +lat_1=29.5n +lat_2=45.5n +lat_0=23.0n
> +lon_0=96.0w +x_0=0.0 +y_0=0.0 +units=us-ft +datum=NAD83"
> srs.ImportFromProj4(proj4str)
>
> lyr = ds.GetLayer()
> lyr.SetAttributeFilter("cat = " + cat)
> outds = drv.CreateDataSource(gmlout,options = ["FORMAT=GML3"])
> outlyr = outds.CreateLayer(outlyrname,srs,lyr.GetGeomType())
> inLayerDefn = lyr.GetLayerDefn()
> for i in range(0, inLayerDefn.GetFieldCount()):
> fieldDefn = inLayerDefn.GetFieldDefn(i)
> outlyr.CreateField(fieldDefn)
> outLayerDefn = outlyr.GetLayerDefn()
>
> for feat in lyr:
> geom = feat.GetGeometryRef()
> outfeat = ogr.Feature(outLayerDefn)
> for i in range(0, outLayerDefn.GetFieldCount()):
> outfeat.SetField(outLayerDefn.GetFieldDefn(i).GetNameRef(),
> feat.GetField(i)) geom.AssignSpatialReference(srs)
> outfeat.SetGeometry(geom)
> outlyr.CreateFeature(outfeat)
>
> Thank you,
> Elke
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