Use 3d-camera for 2d mask

[DJMartin]

Hey! I have a question about creating a matte within a 3d-comp. Instead of doing a 2d track, I want to use the 3d camera in the comp. I could place 3d-objects a render that out with an alpha and use it, but I want is to create bezier curves which use the 3d-track.

The camera is locked into place on a tripod. But since I allready have a 3d solution, I don't want to use extra time to create a 2d track.

Thanks!

[Gringo]

Hi!
Connect your Camera3D to a Locator3D, use its point output to connect your mask's center to (RMB>Connect To>Locator3D>Position)

[DJMartin]

Thanks, it worked! But what if the scene has a zoom, which is the case in my shot. There are no size-value I can connect to.

[Gringo]

Connect mask's size to the camera's Angle of View using an expression (it needs some trigonometry).

[Gringo]

I couldn't add an attachment, so see an example here:
http://www.pigsfly.com/forums/index....ndpost&p=18851

[DJMartin]

Thanks! Great example. Do you have any recomendations when it comes to learning expressions for fusion?

[Gringo]

Expressions are definitely worth learning if you make rather complicated compositing with a lot of dependent objects.
They save a lot of time and can be the first step to simple scripting.