3D Camera track retime expression

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1

Hi guys and gals
Can anyone remember how to retime a camera track using a timewarp node and an expression. I can never remember.
Ive shot and tracked something at 50fps. The edit has a time warp with a curve so Id like to effect the track accordingly.

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2

Make sure the tw curve is built in timing, not speed. Then paste it onto an axis’s pos.x channel or something and use eval().

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3

You ever get this working @PeteRypstra?

4

Paste this expression into you new camera;
eval (Camera, TW.Timing)

Where “Camera” is your original tracked camera and “TW.Timing” is the Timewarp used to retime your tracked plate.

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5

Thanks for the tip Angus and Brian… I seem to remember that Angus.
I still havent got round to trying it as the edit has changed a few times now :sob:

6

(v2021 + fbx imported Camera)

if it is an imported camera like fbx , i found that you cant copy and link the tw.timing to the camera expression.

you need to get a variable (matchbox) into the action , link it there and link the attributes one by one from that .
For ease of use . Let say you do it from pftrack -> pick the fbx 2010 RPY
you will have to add then in the position the and rotatiion attributes one by one
If it is flame camera i think it’s easier than this

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7

As a rule of thumb I personaly do the following …

all of the above is if the TW is flow based

If it is frame based ( round numbers and not the inbetween)
you should add a
round ( blabla.timing ) on the variable
or
ceil (…)
Similar for the action native camera … adjust as needed or be really specific on the tw on frame by frame basis

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8

Thanks George… Will check it out

9

eval(TrackedCamera,(BatchTimewarpNode.Timing))

For camera fbx to use eval predictably, only place expressions on the gross transformation channels.

This means only make expressions for the camera’s position, aim, roll and FOV channels

10

does anybody know how to bake this new camera onced the expression is applied. I can’t get my new tw_camera to bake down the animation. Everytime i exit the batch setup the camera loses the attached expression.

11

Hey… Sorry… a bit slow but there is a Bake button in the channel editor. Im sure you found it