[Gvsig_english] Raster georeferencing

[ernesto sferlazza]

Thanks to Juan Lucas Dominguez Rubio, I have solved the "mistery" (in
my mind) regarding the difference between "affine" and "polinomial 1st
order"  transformation.
The transformation is mathematically the same thing, but in the first
case ("affine") the transformation is performed "on the fly" by the
GIS sw that interprets the .wld file (containing skew axes parameters
not null) created with the georeferencing tool, while in the latter
case ("polinomial 1st order") the original raster is resampled in a
new georeferenced raster.
I have some little remarks regarding the procedure.
1) If  "affine transformation" option is selected there is not any
output raster to be created, so the output file input box should be
disabled;
2) the selection of the raster to be georeferenced in the window is
redundant, since the raster is the same selected in the "generic
ToolBar Panel" of the view;
3) the default size of output pixel should be proposed after the input
of Ground Control Points and not fixed antecedently;
4) once starded the "affine" transformation "test" it should be useful
(expecially in the case of georeferencing without target georeferenced
cartography) a message window informing that the .wld file has been
correctly created.

Best regards

Previous message:
> De: gvsig_internacional-bounces at listserv.gva.es en nombre de ernesto sferlazza
> Enviado el: mi? 14/10/2009 9:53
> Para: gvsig_internacional at listserv.gva.es
> Asunto: [Gvsig_english] Raster georeferencing
>
> Hello list and developers
> The algorithms at the moment available for raster georeferencing are
> "affine" and polinomial (1st, 2nd and 3rd order). The question I
> retrieve is: aren't "affine" and "polinomial 1st order" the same
> transformation?
> Anyway, nothing happens when I select "affine" transformation and try
> to start the process.
> [...]
> Ernesto Sferlazza

-- 
ing. Ernesto Sferlazza
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