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I'm using the Orfeo Toolbox Monteverdi in combination with QGIS in order to produce classified vectors of vegetation cover which I then use in maps in QGIS. (I can't use the QGIS OTB plugin because as far as I can tell it doesn't run on OS X - I'd be pleased to be corrected on that though).

Versions:
Monteverdi 1.10 (edit - just updated to 1.12 and tried that, same result)
QGIS 1.80
OS X 10.6.8

When I load the resulting shapefile into QGIS, it always appears displaced by about 75km to the north east of where it should be. As far as I can tell it's not a datum/projection issue as the CRS is the same for all layers.

My work flow is as follows:

  • produce georeferenced raster image from scanned jpg in QGIS
  • load raster in Monteverdi
  • perform supervised classification using SVM Classification tool
  • export resulting classified vectors as shapefiles
  • open vectors in QGIS

The vectors then display at a location different to the original georeferenced image.

I'll post the files of interest if anyone would like to check them out to see if I'm doing something wrong. http://bit.ly/NCXasm - original GeoTiff raster (270kb zipped)
http://bit.ly/TDFWiS - final vectors produced in OTB and then merged to a single shapefile in QGIS (119kb zipped)

Any assistance or advice would be much appreciated.

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1 Answer

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The OTB plugin for QGIS is obsolete. You need to install the SEXTANTE plugin, that among the others allows you to to run OTB tools (and GRASS, SAGA, R, and much more). AFAIK it works also under OsX.

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Thanks for that - I have just discovered SEXTANTE and I'm learning how to use the GRASS tools - however, it still doesn't answer my question of why the shapefiles produced in Monteverdi are projecting 75km out of place. Regarding running OTB tools through SEXTANTE, I think this still requires the OTB applications to be installed on the system, which is not possible in OS X (once again, happy to be corrected though). – Chid Gilovitz Aug 15 '12 at 10:45
sorry, my answer was intended to be just a comment. Of course you will need OTB installed on your system, but I guess that also Monteverdi needs OTB installed, right? Then just point the Sextante plugin where the OTB binaries are (there a menu entry that allows you to do so). About your real problem: the raster is in the 4283 CRS while the shapefile in in 4326 (wgs84). It this as expected? – Giovanni Manghi Aug 15 '12 at 11:26
Cool, thanks - comments definitely welcome. As I understand, Monteverdi is a self contained application - obviously it contains all the OTB libraries, but they are not available to other software. And Monteverdi is the only way to run OTB natively on a Mac. – Chid Gilovitz Aug 15 '12 at 11:37
Re: difference in CRS, thanks for pointing that out, but GDA94 is almost interchangeable with WGS84 - I think there is a maximum difference of a few meters. Reprojecting it doesn't make any difference. – Chid Gilovitz Aug 15 '12 at 11:43
It's very odd, the shift between the two files appears to be exactly 0.5 of a degree of latitude and 0.5 of a degree of longitude! Perhaps it would be convenient to affine the vector file to the raster? "Translation x" and "Translation y" will both be -0.5. Nick. – nhopton Aug 15 '12 at 11:45
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