[Qgis-developer] Raster resampler branch

[Marco Hugentobler]

Hi Tim

Thanks for looking at the branch. I agree that the ui should be improved 
and I appreciate help in this regard. Hope we can work on the ui design 
(and on other issues in the raster branch) in Lyon.

 >- Its also not obvious what the threshold is where the large kicks in
 >over the small scale resampling approach

The treshold is the zoom level where one screen pixel equals a source 
raster pixel (the zoom level applied with the 'zoom to best resolution' 
function).

>- the number spin box - its not obvious what it is for

It is the maximum oversampling ration for the average resampler (afaik UMN has the same parameter). Depending on the zoom-level, the average resampler pulls data in higher resolution than on screen (depending on raster source resolution). A value of 2 e.g. ensures the resampler does not pull more than 4 times the screen resolution when zooming out.



Regards,
Marco



On 06.04.2012 00:45, Tim Sutton wrote:
> Hi Marco
>
> On Wed, Apr 4, 2012 at 4:23 PM, Marco Hugentobler
> <marco.hugentobler at sourcepole.ch>  wrote:
>> Hi devs / power users
>>
>> Today, I've uploaded a lot of changes to the raster_resampler branch on
>> github ( https://github.com/qgis/Quantum-GIS/tree/raster_resampler ).
>> Compared to the previous version (which already provided resampling
>> capabilities and code refactoring into raster renderer classes), there is
>> now quite a lot of GUI refactoring. The style tab of the raster properties
>> dialog now contains an embedded renderer dialog for the current renderer
>> type (similar to how it is in the vector props. dialog). Furthermore, it is
>> now possible to dynamically add new raster renderers and corresponding
>> dialogs.
>>
>> I'm interested in feedback and like to discuss the raster changes also in
>> Lyon. The user interface could be improved for sure and there will most
>> likely be some new bugs. If you find one, please fill a ticket and assign it
>> to me.
>> Note that the branch also has a number of advantages:
>> - Raster look much nicer with resampling
>> - The raster banding issue when printing transparent layers is solved
>> - Fixes problem with raster transparency band that was not saved in master
>> - Efficiency has been improved for some common cases (e.g. faster lookup
>> when rendering paletted rasters)
>> - It is now easier to make changes in the raster layer class since most of
>> the symbology and rendering related code is moved out of QgsRasterLayer.
>>
> I've done a bit of testing with this it seems to be working well. Some comments:
>
> - the user interface needs to be sorted out for the symbology tab -
> the load button sits too far from the min/max controls. Ultimatelye I
> think we need to completely rethink the style ui - maybe using a
> property list would be better....
> - Some of the settings are not intuitive - its not obvious how you
> return to the default behaviour for the large/small scale combos
> - Its also not obvious what the threshold is where the large kicks in
> over the small scale resampling approach
> - the number spin box - its not obvious what it is for
>
> Other than those issues it was working well for me though I still need
> to test it with some of my larger datasets.
>
>> The next thing I'm planning to make in the branch is to add project file
>> transformations. The new xml format is different than the old one, so old
>> symbology settings won't load properly from project file right now.
> Yes that would be good!
>
> Regards
>
> Tim
>
>> Regards,
>> Marco
>>
>> --
>> 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
>>
>> _______________________________________________
>> 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