Colin Knowles wrote: > Hi, > I'm currently battling the same issue with VPB. But with a much higher > resolution data set , in the order of 12.5cm res terrain and 4cm imagery. > When viewed in other 3d software under WGS84 projection the terrain and > aerials line up 100% - however once passed through to VPBmaster the terrain > and aerials have some huge reprojection issues. The terrain has an offset of > up to 1m in places horizontally - this is very apparent because the terrain > is for a city scene and the footpaths have a 12.5cm vertical step in them. > Along with the offset the terrain also no longer follows straight lines > (typical curb line between two corners) - and meanders back and forth > creating a jaggered edge. > This has only just occured since we moved over to a Linux box so I'm > wondering if the GDAL's are at fault - our programmers currently looking into > it. > Sorry I couldn't be of more help , but you are not alone on this one.
I spoke with Robert about it, and the consensus is that the code in there may not be 100% correct. There's a #define in VPB's SourceData.cpp called SHIFT_RASTER_BY_HALF_CELL. AFAIK, it's not on by default. I don't think it will solve things, because it seems to be applied universally whereas I think it should probably only be applied to raster imagery, not raster DEM data. Robert couldn't recall off the top of his head who had added the SHIFT_RASTER_BY_HALF_CELL option, and I haven't dug through subversion to see. I suspect this is biting more people than realize it, and it should be fixed. I don't have anyone who is willing to fund the work to track this down, isolate it and fix it, but if someone is concerned about it and willing to step up to sponsor work on it, I think it is fixable. For most people, the error margin is too small to worry about. I'd be curious if you find it is related to a specific Linux/GDAL, as I don't think that's the case myself. > Cheers, > Colin > K2VI.com -- Chris 'Xenon' Hanson, omo sanza lettere Xenon AlphaPixel.com PixelSense Landsat processing now available! http://www.alphapixel.com/demos/ "There is no Truth. There is only Perception. To Perceive is to Exist." - Xen _______________________________________________ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
