[gdal-dev] gdal_rasterize usage problems

[Frank Warmerdam]

Andrew Brooks wrote:
> Thanks for the help everyone, I'll summarise when I get it all working ;-)
> 
> Jamie Adams <jaadfoo at gmail.com> wrote:
>> Are your files in the same projection?  I know gshhs is projected in wgs84
>> by default, and I see your raster is in British National Grid.
> 
> To what extent do they need to be in the same projection?  Isn't a change
> of datum sufficient?
> 
> Firstly, is gdal_rasterize not capable of performing the change of SRS
> internally itself?  That would save having to use ogr2ogr to write a new
> vector file for every image.

Andrew,

While it could be made to do so, gdal_rasterize does not currently reproject
the vectors on the fly.

> Secondly, how closely do the vector and raster SRS need to match?  Surely
> as long as both are WGS84 (for example) that should suffice?  But when I
> try to rasterise a WGS84 vector onto a WGS84 Mercator raster it complains
> and doesn't work.
> 
> Thirdly, when I "reproject" the vector to Mercator first and then rasterize
> it does work, to an extent, but it smears random extra vectors across the
> raster :-(  It does this for both gshhs_land and v0_landmass so I don't
> think the vector itself is the problem.

I'd guess this represents a world wrapping problem but if you can demonstrate
the issue it might be appropriate to file a ticket.

Best regards,
-- 
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