[Gdal-dev] Looking for huge vector dataset

Mateusz Loskot mateusz at loskot.net
Wed Mar 7 02:36:04 EST 2007

Martin Daly wrote:
> Peter,
>> You've probably got all you need at this point, but just in case
>> you don't Statistics Canada has published it's street network data
>> as gml, shp and tab files.  There are some smaller boundary polygon
>> data sets available at no cost, but not as large as what you are
>> seeking, I think.
>> An index to the data can be found here:
>> http://www12.statcan.ca/english/census06/geo/index.cfm
> I just re-checked having looked at the data when it first became 
> available, and there are still no GML Application Schemas in the 
> downloads.
> Are they available?  Without these, GML parsers cannot find out how
> the GML/XML is structured, e.g. which element is actually the
> Geometry. That makes the data unusable except in GML parsers that
> have an additional - arguably redundant - configuration file.


GML driver in OGR does not utilise any XML Schemas for GML:

"In contrast to most GML readers, the OGR GML reader makes no effort to
read the format XML Schema definition of the feature classes in a GML
file. Instead it attempts to automatically discover them and their
associated properties by scanning the file and looking for "known" gml
objects in the gml namespace to determine the organization. While this
approach is error prone, it has the advantage of working for GML files
even if the associated schema (.xsd) file has been lost."


Mateusz Loskot

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