[Qgis-developer] Re: Raster providers

[Marco Hugentobler]

> Agreed, int to double conversion could be optimal.

oops, that should be 'Agreed, int to double conversion could be problematic'

Am Dienstag, 18. Januar 2011, um 09.19:23 schrieb Marco Hugentobler:
> > I thought that if data type of the source is integer the provider
> > could represent them as floating point. Byte can be represented as
> > integer. Bad solution however.
> 
> Agreed, int to double conversion could be optimal.
> 
> What about an approach where the out-of-bound values are assigned the last
> value only if reprojection is used (and if the layer does not have a null
> value)?
> 
> This would be quite similar to your current approach, except that people
> will have the appropriate raster appearance if they don't use reproj. And
> if they do, they have an undesired border, but still the right colors in
> the raster area.
> 
> Regards,
> Marco
> 
> Am Montag, 17. Januar 2011, um 17.34:22 schrieb Radim Blazek:
> > On Mon, Jan 17, 2011 at 10:06 AM, Marco Hugentobler
> > <marco.hugentobler at sourcepole.ch> > Using NaN sounds like a good idea
> > and Qt has platform independent support for
> > 
> > > it (qIsNan & co.).
> > > All other solutions I can think of seem to be more complicated (e.g.
> > > force a transparency value only if raster is reprojected).
> > > 
> > >>float + NaN for byte/int?
> > >>
> > > This is not clear to me. Could you explain your approach for byte/int?
> > 
> > I thought that if data type of the source is integer the provider
> > could represent them as floating point. Byte can be represented as
> > integer. Bad solution however.
> > 
> > Radim


-- 
Dr. Marco Hugentobler
Sourcepole -  Linux & Open Source Solutions
Churerstrasse 22, CH-8808 Pfäffikon SZ, Switzerland
marco.hugentobler at sourcepole.ch http://www.sourcepole.ch
Technical Advisor QGIS Project Steering Committee