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How was focal length calculated for the iPhone 12 in the example?

See original GitHub issue

In the example in data/iphone.py the focal length is computed as self.focal = self.raw_W * 4.2 / (12.8 / 2.55). I am wondering what the specific constants mean?

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State:
Created a year ago
Comments:7 (1 by maintainers)

Top GitHub Comments

2reactions

chenhsuanlincommented, Jun 8, 2022

Hi @reynoldscem @jere357, sorry for the late reply. 1/2.55 was the sensor size I got from here. An easier way might be to use the 26mm FF-equivalent focal length (see here), and then get 3024 (#pixels in width) / 24mm * 26mm = 3276, which would get you similar answers as in the code. I’m not entirely sure these are the right way to get the intrinsics (not an expert), but from my experience, the focal length usually doesn’t need to be super accurate to get NeRF/BARF working.

1reaction

reynoldscemcommented, Jun 9, 2022

Thank you for the reply @chenhsuanlin

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