this is my first post as i only discovered the david scanner and community today in fact, i haven't even tried david out yet! so forgive in advance my ignorance...
anyway, I was wondering about 3d scanning for a while and some web-searches brought me here. I was interested to read the david technical paper, and then found this active community, which was a nice surprise.
via this forum, I found a link and youtube video to the work of
Song Zhang - http://www.math.harvard.edu/~songzhang/ - and I spent the afternoon reading his phd thesis on phase-shift imaging.
I don't know anything about camera calibration, computer vision, etc, but I am a good programmer (from the games industry) and after reading about his thesis, it seems that phase shift technique (which in his case is capable of realtime capture in 3d at 120 frames per second! see http://www.youtube.com/watch?v=DiY45jALWjE
and in fact the technique seems to me to be very easy to program -at least in an approximate, rubbish, 'homebrew' style. a simple implementation would not be attempting to solve all the interesting and hard parts that for example david solves, eg shape matching, absolute geometry scale, etc. however basic 'heightfield' type output seems possible as a short term project.
has anyone here tried this, and if not, I think I might give it a go (free time permitting - and lack of a working projector not withstanding)! any input or thoughts on pitfalls / any already existing successful or failed attempts at things like this / etc appreciated.
mm_alex wrote:I spent some time this saturday coding, after borrowing a video camera and a projector last week
here is my first attempt. it's from 3 640x480 greyscale video frames of 3 fringe patterns, taken from a single front view. (the model is shown here from the side so you can see where the scan 'ends' due to shadowing)
there are large systematic errors leading to the 'ridges' on the model, which should be removable by more careful calibration of the camera's gamma curve. and I'm doing no filtering for noise or outliers at all. still, it's promising for only a few hundred lines of (disgusting, horrible, magic-number-ful) c code.
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