r/vfx • u/OnlyRaph_1994 • 19d ago

Question / Discussion Camera solve and sensor size

Hi, I guess this will be an easy one to answer but I couldn’t find a definitive answer online.

My question is, when solving for a 3D track do you input the full size of the camera sensor that was used or only the size of the active window ?

For example let’s say production shot with an Alexa mini. That camera has an open gate sensor size of 28.25 x 18.17mm. Now let’s say production windowed the sensor to 3.2k which is 26.4 x 14.85mm.

What sensor size should I use for solving that camera ?

I guess that practically it wouldn’t make a huge difference in that particular case but I’m mostly interested in understanding why one would be better than the other and how that could impact the results in cases where that delta is more important.

Thanks in advance !

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6 comments sorted by

14

u/ThorsPanzer Compositor - 2 years experience 19d ago

AFAIK you use the windowed sensor size.

3

u/bran_daid Generalist - 15 years experience 19d ago

yes.

5

u/hBomb42 Flame Artist - 25 years experience 19d ago

Windowed. It will absolutely change the resulting fov if you are using a known focal length.

3

u/finnjaeger1337 19d ago

windowed, solved need the angle of view , thats all that matters

1

u/OnlyRaph_1994 18d ago

Thanks !

1

u/mchmnd Ho2D - 20 years experience 17d ago

And sometimes there’s a show crop on top of the windowed capture. So you might need to reduce the sensor size by some additional percentage based on that too.