[Qgis-developer] Raster rendering difference tracked down

[Peter Ersts]

Tim and Marco,

Here is a little update. I have tracked down the difference in rendering 
behavior, which is causing the two units tests to fail, to revision 
8440. This was the merge into the trunk of the Render Context Branch. 
More specifically, I believe the difference has to do with the scale 
factors that are being computed in QgsMapRender.cpp.

As it is right now, I will say the test results for the landsat_basic 
looks like it has artifacts compared to the expected result in the area 
being marked as different. However, when you load the original raster 
data for the landsat_basic test and 'Zoom to best scale' the displayed 
result does not exhibit any artifacts. So I think the next logical place 
to start digging around is the QgsMapRender->setExtent() and looking 
more at the scale factors, unless anyone has other ideas.

-pete

-- 
====================================
Peter J. Ersts, Project Specialist
American Museum of Natural History
Center for Biodiversity and Conservation
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Web: http://biodiversityinformatics.amnh.org
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