I have a high resolution orthophoto of an area I want to rebuild in sketchup and therefore want to lign it up (georeference it properly), but all the scaling and everything I tried so far did not help matching it exactly up with the sketchup 8 provided google earth pictures.

I figured out, that it must be due to the fact, that my pictures are in the ETRS89 UTM32N date and the sketchup photos in another, I assume it should be Google Mercator as I researched so far.

(I tried and succeeded matching it using the openlayers plugin in QGIS and the on the fly function, but when I zoom in, everything is out of order again.) And even if I would not have the zoom in problem, how could I export the layer with the new projection?

I think it´s not possible in QGIS, since you can only save project files. So is there a nother capable freeware I could use?

Please help me, any hints very much appreciated. Thank you for your help, Os


There are a number of factors going on here. First, Google Earth is not as accurate as people think. Depending on the area, the imagery can be off as much as 50 meters. This issue also occurs in open source provided data, such as Open Layers. Does your aerial imagery have a projection? IF it does, but don't you shift the models and photos in SketchUp, its really easy to do, as things are components and groups. If you are more interested in reprojecting your imagery to match the shift in Open Layers, I would suggest you use the Georeferencer tool. This will allow your to collect GCPs from the map source in QGIS, and project your source imagery. When you are satisfied with the georeferencing and RMS error, you can export your imagery to a new file with a new project.

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