[Qgis-developer] Re: Raster providers

[Radim Blazek]

On Thu, Jan 13, 2011 at 9:04 AM, Marco Hugentobler
<marco.hugentobler at sourcepole.ch> wrote:
> The approximate reprojection would be cool. Wouldn't it be better to implement
> it on rasterlayer level instead instead of QgsRasterDataProvider::readBlock?
> Like that, all providers would have reprojection capabilities (e.g. GRASS
> too).

QgsRasterDataProvider::readBlock can be either used (inherited) by
provider (including GRASS) or it can be reimplemented in the provider.

> With one of my favorite test dataset, I noted a problem with automatic
> assignment of nodata value and automatic insertion into the transparency list.
> In that case, the raster is a colortable map (byte) and has no nodata value.
> So 255 is set to transparent and the map appears completely different than
> expected...

I'll look at it, can you put somewhere on Web a piece of that raster?

> Is it correct that the draw() method which returns QImage is not necessary
> anymore (or only for API compatibility for now)? Seems it can be handled quite
> nicely with QImage::bits().

No, at moment it is not used, it was used by providers returning image (WMS)
but I have used another data type ARGBDataType instead.

Radim

> In the future, it would be nice to have also support for create() and write()
> operations in the provider interface (and the gdal provider). Then I could
> port rastercalculator & terrain analysis to use the provider interface.
>
> Regards,
> Marco
>
>
>
>> Radim
>>
>> On Mon, Jan 10, 2011 at 9:36 AM, Marco Hugentobler
>>
>> <marco.hugentobler at sourcepole.ch> wrote:
>> > Hi Radim
>> >
>> > Nice to see you are making good progresses with raster redesign!
>> >
>> > Please give the dev team a bit time to review all the changes. I'd like
>> > to have a closer look at the code. However, it's my first day back at
>> > work, so it could take a few days until I can give feedback.
>> >
>> > Regards,
>> > Marco
>> >
>> > Am Samstag, 8. Januar 2011, um 20.26:24 schrieb Radim Blazek:
>> >> Hi all,
>> >> new raster providers are ready for testing. The work is not yet
>> >> finished but all the old functionality should be available. Current
>> >> status:
>> >>
>> >> - GDAL: on-the-fly reprojection via gdal warp, quite slow, I have not
>> >> yet implemented the trick used in Mapserver Marco pointed me to.
>> >> Please let me know, if you consider the speed at least acceptable for
>> >> real work. The speed depends especially on output display size.
>> >>
>> >> - GRASS: all the old functionality is back, the data are provided
>> >> instead of just a picture so that it is possible to assign a style in
>> >> QGIS like it was possible with GRASS via GDAL, reprojection is not yet
>> >> implemented
>> >>
>> >> - WMS: should work like before, the requested SRS does not yet follow
>> >> current project projection
>> >>
>> >> Please test the raster providers branch and let me know about problems:
>> >>
>> >> svn co https://svn.osgeo.org/qgis/branches/raster-providers
>> >>
>> >> I would like to merge the branch to trunk and continue the work in
>> >> trunk.
>> >>
>> >> Radim
>> >> _______________________________________________
>> >> Qgis-developer mailing list
>> >> Qgis-developer at lists.osgeo.org
>> >> http://lists.osgeo.org/mailman/listinfo/qgis-developer
>> >
>> > --
>> > 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
>
>
> --
> 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
>