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Using a calibrated camera #42

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kozuch opened this issue Jul 6, 2017 · 2 comments
Open

Using a calibrated camera #42

kozuch opened this issue Jul 6, 2017 · 2 comments

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@kozuch
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kozuch commented Jul 6, 2017

This is not an issue but rather a question.

I would like to use SfM with a calibrated camera - I looked at the source code a bit. I see there is a "bundle adjustment" done probably in all SfM libraries. Is it possible to plug in (=hard code) my camera parameters (focal length, principal point or maybe even some more?) to your code and get better results?

What I am looking for a classical "multiview" SfM where one has 100 photos of a single object but I need to reconstruct from continuous sequence (moving car) - I want to reconstruct from 2 consecutive frames (or maybe more, but the fewer the better) of a monocular sequence. I can imagine this can be done with bundle adjustment too but I guess when I know both my camera parameters and the exact camera translation/rotation then 3D reconstruction may be done without bungle adjustment (much simpler) and maybe even more accurately?

I know my absolute translation and want to employ OpenCV's recoverPose and then do very simple triangulation to get my 3D scene. Could you give me some hints please?

@kozuch
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kozuch commented Jul 21, 2017

@royshil Would you mind replying please?

@royshil
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royshil commented Jul 21, 2017

@kozuch
Of course, just don't pass the focal into the Ceres cost function in:
https://github.com/royshil/SfM-Toy-Library/blob/master/SfMToyLib/SfMBundleAdjustmentUtils.cpp
The center of projection is anyway not optimized.
Take a look at that file, and you'll figure it out before long.

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