[Gdal-dev] VRT format Schema

[Frank Warmerdam]

Antoine Hue wrote:
> Since I got no answer to my question about an available DTD or Schema 
> for the VRT format; and since I wanted to understand a bit more about 
> the VRT, I have created a schema for it based on the HTML doc and based 
> on code browsing.
> Please find it attached as well as a picture generating from it by oXygen.

Antoine,

I skimmed over the .xsd file, and it looks good though I didn't try to
establish how comprehensive it is.  When you are satisfied with it's
completeness let me know and I will commit it in gdal/frmts/vrt.

However, I can't promise to keep it up to date as things evolve.

> There are still a few dark zones and area to improves:
> - ComplexSource and AverageSource need a complete definition
> - Better definition of the subClass property of the VRTRasterBand needed.

What did you need to know?  It seems that values include "VRTWarpedDataset",
"VRTDerivedRasterBand" and "VRTRawRasterBand".

> - An explicit definition of the raw raster source (to go with 
> SimpleSource, KernelFilteredSource,..) would improve homogeneity.

I'm not sure what you mean. Isn't the ".vrt Descriptions for Raw Files"
on the gdal_vrttut.html page appropriate?

> - Kernel's Coefs and Size could be more explicitly defined.
> - Same thing for GeoTransform
> 
> I have validated it with examples of the VRT HTML doc (tutorial). 
> Examples need to get modified a bit to refer to the schema as shown in 
> the example file attached.
> 
> When completed, we may set it online on the www.gdal.org, some 
> modification of the definition and link is then needed.
> 
> I think VRT really makes sense as a way to geo-reference rasters. It is 
> quite extensive and may get embedded inside a larger XML document.
> For this latter alternative, it may make sense to wrap into an XML 
> namespace.
> We may also extend it to better support rasters representing elevation.

Were you thinking of the .xsd file as being primarily useful for
automated validation of .vrt files?  As educational?

Best regards,
-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGF, http://osgeo.org