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Alembic: Camera focal length animation not importing
Confirmed, NormalPublicTO DO


System Information
MacOS 10.13.3

Blender Version
Broken: 2.79 5bd8ac9

Short description of error

When importing camera in FBX or ABC file (exported from Nuke), the animation of focal length is not importing. It's being set to a constant value according to frame 1. Other values are imported correctly.
If I reimport to Nuke, the focal length is correctly animated.

Camera files attached.

Event Timeline

I cannot speak for FBX files, but in the case of Alembic files this is not a bug, but a limitation of the current implementation (however I used to work on a patch for supporting such features D2324).

I can confirm that is a known limitation for FBX.
According to documentation, Focal length is not supported, yet.

It is not the first time that feature request is made to be able to work with Nuke.
I let @Bastien Montagne (mont29) close this report or attach it to a duplicate.

Implemented import & export of camera focal length in FBX now, so will re-assign to @Sybren A. Stüvel (sybren) for the Alembic part of it…

Sergey Sharybin (sergey) lowered the priority of this task from 90 to Normal.Mar 6 2018, 4:00 PM

Not sure why, but focal length keying worked for me in Blender Version 2.79 (2.79 2017-09-11, Blender Foundation), but does not work in Version 2.79b (2.79b 2018-03-22, Blender Foundation).

I've attached the FBX i'm testing with.

@Jesse (FreakTheMighty) : cant reproduce.
in 2.79, the provided FBX wont import Focal Length [but that is expected since rBAb890f0d7e8a6 isnt included]
in 2.79b (or onwards), the provided FBX will import Focal Length [bunch of keyframes, but all very similar -- around 8.1/8.2mm]

I don't think we can use the same approach as @Bastien Montagne (mont29) did in b890f0d7e8a6 for Alembic. The FBX addon loads the entire animation into a Blender F-Curve at import time. This contrasts the streaming approach we use when reading Alembic, where modifiers and constraints are used to read the Alembic file at a certain timecode and apply that to Blender. @Kévin Dietrich (kevindietrich) 's approach in D2324 looks good, but is almost 3 years old already.

This limitation is really annoying to insert Blender in a consistent pipeline.
Maybe we could have an option to import data from an alembic file (and thus avoiding the linking issue)

Bastien Montagne (mont29) renamed this task from Camera focal length animation not importing to Alembic: Camera focal length animation not importing.Jul 13 2020, 2:49 PM

Hi there,

I'm new to this forum, so apologies if I'm breaking protocol. I've stumbled across this issue - I'm trying to import an alembic camera from maya, and It's not pulling in the animated focal length. Was there ever a solution to this? (Using blender 2.90.1 - Windows 10).



@Joel Prager (jpvfx) This is not a forum, it's the bug/task tracker for Blender development. As this task is still open, that means that it hasn't been solved yet.