FRotator/Euler Angles: Rotation Order?

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1

I am trying to export a camera position and orientation from Unreal into Maya. The position part I’ve figure out, but I am having trouble with the rotation conversion.

I can’t seem to find a definitive document on UE4 stating the rotation order used for euler angles? I do know that Unreal is z up, and I see from the FBX static mesh import code that Unreal is left-handed, correct? But I need to know that rotation order in order to have the full picture for a correct conversion.

My maya coordinate system is right handed, y up, and I can use whichever rotation order I want. I believe I’ve figured out the manipulations I need to do to get an euler rotation from Unreal into this maya coordinate system, but I am still getting a little bit of error, which I believe is due to difference in rotation order?

Cheers

2

I am also having trouble making sense of the rotation conventions in UE4.
There is little to no documentation.

I asked a similar question.

3

For anyone interested, here is a python snippet of what I ended up with for converting Unreal Position and Unreal Euler angles to Maya Position and Maya Euler angles.

from maya.api import OpenMaya as om

unreal_pos = [ <x>, <y>, <z>]
unreal_rot = {
    roll: <x rot>,
    pitch: <y rot>,
    yaw: <z rot>
}

if cmds.upAxis(q=True, axis=True) == 'y':
    maya_pos[0] = unreal_pos[0]
    # swap z and y position
    maya_pos[2] = unreal_pos[1]
    maya_pos[1] = unreal_pos[2]

    maya_rot = om.MEulerRotation(math.radians(unreal_rot['pitch']), -math.radians(unreal_rot['yaw'] + 90.0), -math.radians(unreal_rot['roll']))
else:
    # still need to mirror position on y axis
    maya_pos[1] = -maya_pos[1]
    maya_rot = om.MEulerRotation(math.radians(unreal_rot['pitch'] + 90.0), -math.radians(unreal_rot['roll']), -math.radians(unreal_rot['yaw'] + 90.0))

Note that you also need to convert from cm to whatever units your maya workspace is using.

4

With this snippet were you able to match the orientation of objects from unreal inside of maya? Ive been trying to do the same thing and cant quiet say that i’ve been successful. Partly because i dont really understand Euler Angles and such. When i run the snippet above all i get very small numbers, definitely not the same orientation from maya.

In my example below the object’s orientation are defined by “unreal_rot” and after converting the numbers the orientations does not match in maya. Any help or tips are welcome!

from maya.api import OpenMaya as om



unreal_rot = [ 90, 55, -125.0 ]



# swap z and y position

maya_rot = om.MEulerRotation(math.radians(unreal_rot[0]), math.radians(unreal_rot[1] + 90.0), math.radians(unreal_rot[2]))

print maya_rot[0], maya_rot[1], maya_rot[2]
5

The maya_rot object is describing the rotation in terms of radians, which is why you’re getting small numbers. 180 degrees = pi radians

see math.radians and math.degrees for converting between the two.
https://docs.python.org/2/library/math.html