Brilliant. I am amazed that I actually did almost exactly what you are
outlining, haha. But I was so not sure if I'm doing the right thing, so thanks
heaps for clarifying/assuring!
One day we might end up in the same city and there will be beer payments due!
cheers,
frank
On Mar 7, 2011, at 3:42 PM, Ivan Busquets wrote:
> Hallo, Frank.
> Despite writing that tutorial, I am by no means an expert in matrix and
> maths. :)
>
> But I've learnt a thing or two about how they apply to things like camera
> transforms, etc., so hopefully I'll be able to help with this one.
>
> I think the easiest in your case (easiest to code, not necessarily to
> understand :p) is to start with the camera's transformation matrix instead of
> the Euler rotations. If you want to use Euler angles as a starting point,
> then you'll need to check for rotation order and such.
>
> To get the camera's transformation matrix, i usually do one on the following:
>
> - If your camera doesn't have any other Cameras or Axis driving its final
> transformation, you can simply do:
>
> cam_transform = nuke.toNode('camera_name')['transform'].value()
>
> - If you're interested in getting the final transformation matrix of a
> concatenated set of transforms, I usually use the following to wrap the
> contents of the 'world_matrix' knob into a nuke.math.Matrix4 object:
>
> #########
> def getCameraTransformMatrix(cameraNode):
> m = nuke.math.Matrix4()
> try:
> for i in range(0,16):
> m[i] = cameraNode['world_matrix'].value(i%4, i/4)
> except:
> print "couldn't get all values for a 4x4 Matrix. Identity matrix returned
> instead"
> m.makeIdentity()
> return m
> ##############
>
>
> Finally, once you have your transformation matrix in a nuke.math.Matrix4
> object, getting the lookAt and the Up vectors should be a matter of setting
> the initial direction of those two vectors, and then transform them using the
> matrix.
>
> I.E.
>
> # For a single, non concatenated camera. Otherwise use the helper funcion
> above.
> cam_matrix = nuke.toNode('camera_name')['transform'].value()
>
> # set up initial lookAt vector
> lookAt = nuke.math.Vector3(0,0,-1) # because Nuke's default cam looks at -Z
>
> # Initial up vector
> up = nuke.math.Vector3(0,1,0)
>
> #Final lookAt vector
> lookAt = cam_matrix.vtransform(lookAt)
>
> #Final up vector
> up = cam_matrix.vtransform(up)
>
> # Note that the key here is to use the "vtransform" method instead of
> "transform", since you want to apply the transformation to a direction
> vector, but ignore any scaling or translation.
>
> I think this should get you the right values to go from a Nuke camera to,
> say, a Camera + Aim + Up in Maya (don't have Maya here to check, though).
>
> Hope that helps!
>
> Cheers,
> Ivan
>
>
> On Sun, Mar 6, 2011 at 3:06 PM, Frank Rueter <[email protected]> wrote:
> Hola,
>
> has anybody converted a nuke camera (Euler rotations) to LookAt and Up
> vectors? as used by some other applications
> I am just starting to read Ivan's tutorial on Nukepedia hoping it will shed
> some light on this for somebody with very limited understanding of 3D
> rotational maths (aka "me") but thought I'd spread my feelers in here at the
> same time.
>
> Cheers,
> frank_______________________________________________
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