AE ENHANCERS

Hi,

When I import data from a 3D soft or from a 3D tracker into AE, I need to place and orient a layer to some nulls coming from the 3D data. Instead of adjusting this manually you can use the following expression. Remember that this expression uses three nulls/lights/layers that should be placed on top of the layer to be placed.

Position expression:

Code:

a = thisComp.layer(thisLayer, -1).position;
b = thisComp.layer(thisLayer, -2).position;
c = thisComp.layer(thisLayer, -3).position;

(a+b+c)/3

This places the layer in the middle of the three points.

You then have to add an expression for the orientation :

Code:

a = thisComp.layer(thisLayer, -1).position;
b = thisComp.layer(thisLayer, -2).position;
c = thisComp.layer(thisLayer, -3).position;

n = cross ((a-b),(a-c));
orientation+lookAt(a, n)

This will orient the layer to be parallel with the plane formed by the three points. You'll need to manually adjust the Z orientation though.

Any feedback or suggestions to make it better are really apreciated.

Donat

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Donat Van Bellinghen

I wish I had looked at this a couple of weeks ago as we were doing a lot of camera tracking and had to do exactly what this script is designed for, eyeing it in manually is no fun at all!!
As soon as I get a chance I'll try it out and let you know how it goes.
Glenn Stewart
1k Studios

Hi Donat

I've been trying to use this expression. It seems straight forward.
But when I apply it to a layer with 3 null points in space, the plane does not intersect the 3 null points.
Furthermore, if I change the order of the nulls the Normal changes. I don't get this... the normal would be the same whatever the order, at worst it would reverse direction, but not the orientation.
I cant figure out where its going wrong. The Maths are sound, so why doesn't this work for me. Grrrr!
I could have really used this today.
Any chance of a teeny weeny project example to put my hurting brain at its ease.

dkvfx,

I've check this expression and it worked for me !
I've used the same scenario you've described: 3 Null layers in 3D space in order to position and orient a solid according to them, and it worked great.

Note however for a few things:
1. You have to put the 3D layer JUST below the 3 Nulls.
2. Perhaps your layer is too small and that is why it doesn't intersect the 3 Null points ?
3. Try using square pixels.

Koby.