View Full Version : Tracking CG extension onto real object

08 August 2009, 02:51 AM
Hello, my group are shooting some green screen footage soon. We have a scene though where a real actor is holding a wooden staff in front of a green screen, and we want to track a CG spear head onto the staff. Does anyone have any tips or suggestions on this? We will be placing cards to use as markers on the screen itself for matchmoving the camera. I'm assuming the staff would need markers too, but does anyone know what kind or how many would be best? Any other advice? Thanks very much!

08 August 2009, 12:41 PM
Well it could depend on the software you will be using to track the staff. Will you track it in 3D or just 2D. Will it have fast motion or will it be mostly stable. Will the person holding it hide parts of it from the camera?

But in any case most of the 3D Tracking programs can track objects relatively easy if there isn't much change in the lighting (shadows getting in and out of the object) without using trackers. If you need to place trackers these should be in 3 places of the staff. Top and Bottom is a good start and in case you loose one from the camera move or the staffs movement you could place a 3rd one somewhere between the middle and top of the staff. You will need at least 2 to calculate the angle of rotation of the staff. Don't overdo it with the trackers though or you'll have a hard time removing them in post and you'll end up using the time you won tracking the object trying to replace the trackers with the staff's body texture.

I hope I helped.

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08 August 2009, 12:41 PM
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