Calibration in decode app.

[Pranav]

Hi,
In decode app. how should i insert my intrinsic & extrinsic
parameters values for getting correct 3D reconstruction,as they are
required before determining the absolute(unwrapped) phase?

[Pranav]

Can anyone please give the explanation for how the absolute phase in
the Decode app. is calculated(Is it the
floodfilldecoder::unwrapphase() where it is calculated)??

[Kyle McDonald]

hi pranav,

the decode application does not provide the ability to specify intrinsic and extrinsic parameters. when i created the application i didn't understand epipolar geometry or camera calibration, so i didn't know how to account for any of that.

likewise, the absolute phase is not given anywhere. the unwrapped phase (relative phase) is given by FloodFillDecoder::unwrapPhase() -- yes. however, FastThreePhase is the better implementation, as i mentioned in a previous email. that is done in Unwrap::makeUnwrapped()

https://code.google.com/p/structured-light/source/browse/trunk/OpenFrameworks/apps/structuredLight/FastThreePhase/src/Unwrap.cpp

but for the best understanding of what's happening, you need to look at how all the files work together:

https://code.google.com/p/structured-light/source/browse/#svn%2Ftrunk%2FOpenFrameworks%2Fapps%2FstructuredLight%2FFastThreePhase%2Fsrc

to calculate absolute phase from the relative unwrapped phase you need some kind of marker. i believe song zhang projects a single bright point, but i'm not sure.

once you have the absolute phase, you will need to use your intrinsics + extrinsics to do the conversion to real world coordinates. i can't provide support for this, but there is an opencv implementation of these ideas that i believe handles this step:

https://code.google.com/p/structured-light/source/browse/#svn%2Ftrunk%2FOpenCV%253Fstate%253Dclosed

kyle