[Gvsig_english] thinking about raster reprojection...

[G. Allegri]

I see that a placeholder is already there for
reprojection.... org.gvsig.raster.datastruct.ViewPortData.reProject(ICoordTrans
rp), and looking to the raster rendering workflow, the idea of a reprojector
could be incorporated without breaking anything. I hope to find some time to
work on it.

Giovanni


2011/6/1 G. Allegri <giohappy at gmail.com>

> I've seen that on-the-fly raster reprojection isn't available yet. The only
> solution, meanwhile, is doing a reprojection (wether during file loading or
> as a distinct process) which is performed with a call to gdal warp (though
> JNI calls from WarpFunction, right?).
> This process can be ok for "offline" transformations, but become unfeasable
> for on the fly uses, unless a very small grid is beaing loaded.
> This is not Gvsig fault, it's the gdal reprojection code that has to do a
> lot of work, even if an approximate reprojection is requested (error
> threshold being > 0.0, the default in Gvsig).
>
> A better solution could be to implement something like the Qgis
> RasterReprojector [1], which is created and used during the read od the grid
> datas, without affecting the providers code.
> The raster projector implements a fast, approximated reprojections, which
> can be ok for viewing the raster. An option coul be given to do a precise
> reprojection in case raster processing need the original precision.
>
> A hint for the gdalwarp reprojection: why don't let the user enter custom
> projections in the Reproject dialog? We could make a check to validate its
> syntax against the one accepted by gdal, or simply manage the exception in
> case the projection is not valid...
>
> Giovanni
>
>
> [1]
> http://trac.osgeo.org/qgis/browser/trunk/qgis/src/core/qgsrasterprojector.cpp
>
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