[Qgis-developer] Raster algebra C++

[Alexander Bruy]

Hi Marco,

seems that this is another great addition from your side.

I'll try to build QGIS trunk (r14380) with this patch under
Windows with MSVS Express 2008 and dependencies from OSGeo4W
and get next error:

qgssearchtreenode.cpp
d:\devel\cpp\qgis\trunk\src\core\qgssearchtreenode.cpp(1304) : error C2666: 'pow' : 6 overloads have similar conversions
   c:\program files\microsoft visual studio 9.0\vc\include\math.h(575): could be 'long double pow(long double,int)'
   c:\program files\microsoft visual studio 9.0\vc\include\math.h(573): or 'long double pow(long double,long double)'
   c:\program files\microsoft visual studio 9.0\vc\include\math.h(527): or 'float pow(float,int)'
   c:\program files\microsoft visual studio 9.0\vc\include\math.h(525): or 'float pow(float,float)'
   c:\program files\microsoft visual studio 9.0\vc\include\math.h(489): or 'double pow(double,int)'
   c:\program files\microsoft visual studio 9.0\vc\include\math.h(123): or 'double pow(double,double)'
   while trying to match the argument list '(double, float)'

I change line 1304 as
 res[i] = pow(double(value1), double(mat[i]));

and the I get another errors:

qgisapp.obj : error LNK2019: unresolved external symbol "public: __thiscall QgsRasterCalculator::~QgsRasterCalculator(void)" (??1QgsRasterCalculator@@QAE at XZ) referenced in function "private: void __thiscall QgisApp::showRasterCalculator(void)" (?showRasterCalculator at QgisApp@@AAEXXZ)
qgisapp.obj : error LNK2019: unresolved external symbol "public: int __thiscall QgsRasterCalculator::processCalculation(class QProgressDialog *)" (?processCalculation at QgsRasterCalculator@@QAEHPAVQProgressDialog@@@Z) referenced in function "private: void __thiscall QgisApp::showRasterCalculator(void)" (?showRasterCalculator at QgisApp@@AAEXXZ)
qgisapp.obj : error LNK2019: unresolved external symbol "public: __thiscall QgsRasterCalculator::QgsRasterCalculator(class QString const &,class QString const &,class QString const &,class QgsRectangle const &,int,int,class QVector<struct QgsRasterCalculatorEntry> const &)" (??0QgsRasterCalculator@@QAE at ABVQString@@00ABVQgsRectangle@@HHABV?$QVector at UQgsRasterCalculatorEntry@@@@@Z) referenced in function "private: void __thiscall QgisApp::showRasterCalculator(void)" (?showRasterCalculator at QgisApp@@AAEXXZ)

On Linux I compile this without errors.

Thanks

On Thu, 14 Oct 2010 17:40:03 +0200
Marco Hugentobler <marco.hugentobler at sourcepole.ch> wrote:

> Hi devs,
> 
> A very cool and handy tool is Alexander Bruys raster algebra plugin. It's so 
> usefull in environmental modelling that Tim and I thought it would be good to 
> have it in our analysis library (where it can be used by 3rd party 
> applications too and without the dependency of the numpy library).
> So here is my initial patch that implements a calculator tool as part of the 
> analysis library by extending the search string mechanism.
> 
> 
> Compared to the python plugin, is has some missing features (but they could be 
> added):
> - no 'difference' and 'NDVI' buttons
> - only outputs float32 rasters
> - no possibility to load / save expressions
> 
> On the other side, it has some additional features:
> - Possibility to insert output extent and resolution and do calculations with 
> layers that have different resolutions / extent. If a layer resolution does not 
> match, it is automatically resampled to the output resolution (of course with 
> higher computation costs)
> - Selection of output format
> 
> 
> You can try the functionality by applying the following patch:
> http://karlinapp.ethz.ch/101014_qgis_rastercalculator.diff
> The menu to open the calculator is located under 'Layer->Raster calculator'.
> 
> I didn't apply it to trunk directly, as it needs more testing and there are 
> still some issues:
> 
> - Flex detects a string as raster if it has '@' followed by a single number 
> (the raster band number). Don't know if there are better solutions, especially 
> to avoid conflicts with vector columns named that way.
> 
> - QgsSearchTreeValue is extended with a new type to represent a raster matrix 
> and with new operators and methods doing matrix operations. This class needs 
> some code cleaning before applying to trunk
> 
> - Handling of nodata values could be done in a more clever way: out of band 
> values during resampling receive the nodata value of the input raster band. In 
> case of error (e.g. division through zero), QgsSearchStingValue applies 
> '-100000'.
> 
> - More testing is needed. Especially with the automatic resampling option, 
> there is a high risk for rounding errors. Send me a mail if you found a bug 
> (possibly with a sample dataset and easy instruction on how to reproduce).
> 
> 
> Looking forward for your feedback,
> Marco
> 
> 
> 
> 
> -- 
> Dr. Marco Hugentobler
> Sourcepole -  Linux & Open Source Solutions
> Webereistrasse 66, 8134 Adliswil, 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
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-- 
Alexander Bruy