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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