I have a raster file and I want to perform the method "polygonize". Then the problem occurs, that is shown on the screenshot. It doesn t have anything to do with the rasterfile format, I veryfied. Other functions in the same menue(Raster->Conversion do not work either, because of the same problem). I m using the newest version of Qgis (1.8). Older threads here couldn t (as far as I saw) help either. So: I want to ask if anybody has an idea how to solve this problem? Thanks.
I'm not an expert in the compilation of QGIS (so will bow to greater knowledge and please treat this answer as a suggestion and not gospel), but I can think of two possible reasons for this error:
- If you have a separate instalation of GDAL for a different version of Python (especially Python 3.x) you will get similar errors and GDAL will not work in QGIS until you uninstall your other version of GDAL.
- You have a different version of Microsoft Visual Studio Runtime installed than the version used to compile the GDAL binaries for QGIS. I have both MSVC2008 and 2010 installed. Off-hand I can't remember what the QGIS folk used, so one of those should work. You can get the 2010 version here: http://www.microsoft.com/visualstudio/en-us/products/2010-editions/visual-basic-express and you'll find the 2008 version somewhere nearby. Simply install and then you probably will want to restart your computer.
Given that you can get even as far as you have without getting a Python version error (I get the Python error on start-up), I think the second option is more likely.
PS: BTW the latest version of QGIS is now 1.9 according to the last update I got from OSGEO4W... though the icon still says QGIS 1.8 confusingly enough.