[Qgis-developer] Raster resampling

[Tim Sutton]

Hi Marco


On Tue, Jan 10, 2012 at 12:39 PM, Marco Hugentobler
<marco.hugentobler at sourcepole.ch> wrote:
>
>> Great stuff Marco - I hope to test your changes soon.
>
>
>
> Thanks, Tim. The code is not 100% complete, but already testable. Because
> there are many changes, I'm expecting a large number of bugs. So any report
> about issues is greatly appreciated.

I compiled your branch tonight. I havent tested with a lot of data
sets yet, but two things I immediately noticed were:

- with one of my ecw images the computer began to undergo very high
cpu load with each  zoom / pan event when using bilinear or cubic
interpolation. Unfortunately the dataset is too large for me to share
with you right now - I will try to upload it for you when I get a
chance.
- I noticed a shift (guesstimating in the order of 5-10 pixels) when
switching between the interpolation algorithms

Otherwise (with the test images I have used thus far) it creates nice
smooth tones where before they look pixelated which is great!



Regards

Tim

>
> Regards,
> Marco
>
>
>
> On 10.01.2012 10:29, Tim Sutton wrote:
>>
>> Hi
>>
>> On Fri, Dec 30, 2011 at 3:58 PM, Marco Hugentobler
>> <marco.hugentobler at sourcepole.ch>  wrote:
>>>
>>> Hi devs,
>>>
>>> Recently, I've been working on adding raster resampling to QGIS raster
>>> (http://www.sourcepole.com/raster-resampling-in-qgis). The changes are in
>>> the branch 'raster_resampler' of my github clone
>>> (git://github.com/mhugent/Quantum-GIS.git).
>>>
>>> To add resampling in a clean way, I started a bit of refactoring within
>>> QgsRasterLayer:
>>>
>>> - The new abstract class QgsRasterRenderer is added to replace the
>>> drawingType switch. The method QgsRasterRenderer::draw() is a replacement
>>> for the methods drawMultiBandColor(), drawMultiBandSingleBandGray(),
>>> drawPalettedSingleBandColor(). This should move a lot of code out of
>>> QgsRasterLayer and reduce code complexity. Currently implemented are
>>> QgsPallettedRasterRenderer, QgsMultibandColorRenderer,
>>> QgsSingleBandGrayRenderer
>>> - The functionality of QgsRasterBuffer to draw the raster layer in
>>> several
>>> parts is moved to QgsRasterRenderer base class (same idea of reducing
>>> complexity in QgsRasterLayer).
>>> - QgsRasterResampler has two subclasses for now,
>>> QgsBilinearRasterResampler
>>> and QgsCubicRasterResampler (maybe average would be useful as well?)
>>>
>>> Any objections or suggestions about this? The code in the branch is
>>> mostly
>>> working, but far from being complete.
>>> I'm going to be without internet connection the next few days, but hope
>>> to
>>> get the code to a testable state soon.
>>>
>>> Regards,
>>> Marco
>>>
>> Great stuff Marco - I hope to test your changes soon.
>>
>> Regards
>>
>> Tim
>>
>>> --
>>> 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
>



-- 
Tim Sutton - QGIS Project Steering Committee Member (Release  Manager)
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