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### [HELP] How to make a portal with parallax

Posted: 06/27/2015, 10:42 pm
Hi everyone, I want to ask how to make a portal with parallax like this:
https://youtu.be/4HdnfPHCIGQ?t=3m13s
from 3:13 to 3:40
Does he mentioned something about the track matte?
Thank you so much for helping!
(Does the effect similar to the 3D camera projection tutorial ?)

### Re: [HELP] How to make a portal with parallax

Posted: 06/28/2015, 12:46 am
The key point there is to use moving camera and 3D camera tracking and set the other scene that you see through the portal at a distance behind the portal so that you get parallax. Yes, a track matte is used to mask out the scene seen through the portal. The track matte would simply be a black and white version of the hole in the wall.

### Re: [HELP] How to make a portal with parallax

Posted: 06/28/2015, 4:12 am
star+circle wrote:The key point there is to use moving camera and 3D camera tracking and set the other scene that you see through the portal at a distance behind the portal so that you get parallax. Yes, a track matte is used to mask out the scene seen through the portal. The track matte would simply be a black and white version of the hole in the wall.

Thank you again star+circle for helping!!

But could you explain more specifically about the track matte issue ? I`ve got no idea how to use that in the effect, luma matte or alpha matte?

### Re: [HELP] How to make a portal with parallax

Posted: 07/11/2015, 4:43 am
Let's see if I can explain it better with this example picture.

You need two tracked planes:

1) one for the surface where the portal is, in this case the column. Create Null 1 on this surface

2) second at a distance where the "scene" seen through the portal is. Create Null 2 there.

For the matte, you can create a solid with a mask (the green ellipse), make it a 3D plane and parent it to Null 1 (Alt-drag pick whip Null 1 to move plane to null's position)

Parent the "scene" plate (3D layer) to Null 2 the same way.

Place "scene" layer directly below matte layer and select Alpha Matte from the TrkMat options of the "scene" layer.

Result: The "scene" will be seen through the portal matte, but it will appear to be at a distance behind the column, not right on the column. This gives the shot the parallax it needs to be realistic.

(Obviously the "scene" will need to be appropriately scaled to the distance it is from the portal, so needs to be shot from such a distance. I used a still image from the video to show the principle, the "scene" would have to be wide enough to fill the the portal hole from any angle seen in a given shot.)

Same Null 1 can then be used to place your portal frame on the surface.