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I want to figure out a good Camera Position in an animation movie.
The Camera should be moving.
I have one point A in the Middle of the scene (A is fix).
I have one point B, a Ball or Marble going around A (like earth B around the sun
A) in different heights (not like earth around the sun) and different
circumferences.
Question: I want to get the moving Camera Position C; I want it to be outside
B's circle, always looking at B AND at A.
Since B is moving, C should also be moving.
What would be the formula to get
CX=
CY=
CZ=
based on AX,AY,AZ and BX,BY,BZ?
So there's a straight line from A to B to C.
Thanks a lot!
Chrisir
P.S.
It would be cool when there would be a kinf of Damping.
So when the Marble B is doing a abrupt or fast short change, camera kind of
stays calm.
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Chrisir wrote:
> What would be the formula to get
>
> CX=
> CY=
> CZ=
>
> based on AX,AY,AZ and BX,BY,BZ?
>
> So there's a straight line from A to B to C.
That's probably not what you actually want, otherwise
the balls would stay unmoving in the image? But if you
have points A and B, then V=BA will be a vector from
A to B and, e.g. C = A + 2*V will be point such as
you describe (you didn't specify distance).
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Le 27/02/2011 14:39, Chrisir nous fit lire :
> So there's a straight line from A to B to C.
>
Seconded mail from Christian Froeschlin.
Nevertheless:
let's k be the ratio BC/AB.
the relation is (CB) = k(BA).
which can be rewritten
C = k(BA)+B
...
C = (k+1)*B k*A.
Apply to all coordinates (x,y,z).
> P.S.
> It would be cool when there would be a kinf of Damping.
> So when the Marble B is doing a abrupt or fast short change, camera kind of
> stays calm.
>
That might be some call for a spline.
For instance, you might want to adjust the previous k dynamically based
on the speed of B.
Assumes the positions of B are in the spline, compute the "speed" by
evaluating the spline at t & t+delta, divide that vectordistance by
delta...
Or you could instead average the spline from tdelta to t+delta (with
enough steps) to have the camera more stable.
For better realism, the camera should not know about the futur, so only
averaging from tdelta to t. (or even tlate)
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Thanks a lot!
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