On Tue, 2013-09-10 at 11:11 +0200, Benjamin Ducke wrote: > One of the handiest solutions for extracting 3D data > using SfM is this: > > http://homes.cs.washington.edu/~ccwu/vsfm/ > > It includes georeferencing and can handle the coordinate > ranges that occur in geographical data. It is free > to use for non-commercial applications but unfortunately > not open source.
Most of the underlying tools to that are open source, and they're what I'm using (opensift, bundler_sfm, cmvs/pmvs etc). I've had some limited success so far (not tried aerial imagery), but I don't yet properly understand the work flow or all the options at various stages of the process. I also don't understand yet how to measure the 'quality' of the output (rather crucial). Much more experimentation needed... > > Anyhow, SfM works best when there is a large series > of images with a lot of overlap and small angular > displacement between consecutive images. Traditional aerial > imagery will not always give good results. There can also > be trouble with the simple camera model that some SfM > tools (including VSFM) use. Yes, as I understand it, each point should be in /at least/ 3 images, preferably with about 15° difference in viewing angles between camera positions. > > An open source solution that is optimised for remote > surveying applications is currently lacking, AFAIK. > I think most of the pieces are there assuming you have the cpu & ram to cope with the processing load but they're certainly not integrated into a nice GUI. Also being able to 'rubber sheet' the final point cloud to ground coordinates is not something I've found yet; Doing a '7 parameter' conversion is there, but that's not quite the same. Idle thought: Is this something that could be worked into GRASS? Tim Bowden _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
