Mantra and Houdini Coordinate Systems

[phong]

Hi!

 

Looking at transformation matrices of IFD files really confuses me. For one they seem to do exactly the opposite of what the camera's transformation parameters in Houdini are indicating, which I think is because Mantra moves the scene and there's no actual camera like in OpenGL. However what's really confusing me is if I have a camera with SRT, ZXY order and transformations  rot(45, 30, 0) and trans(10, 5, 0) I get a transformation matrix in the IFD that looks like this:

 

0.866025396499       0.353553407243     0.353553391789          0

0                                0.707106765732    -0.707106796641          0

-0.500000012618      0.612372443928     0.612372417161          0 

-8.66025396499      -7.07106790109       6.53176023263e-008    1

 

Looking at the fourth row, I would expect to see 10 and 5 somewhere, but they don't show up.

 

When I rebuild the same transforms in Nuke I get identical values for each component but for the last row. But the results from the IFD seem illogical to me.

 

I'm really stuck on this, maybe you guys can help.

 

 

Thanks,

 

 

Nhat

 

 

[danylyon]

I can't really help you, but maybe you find some information in the Renderman Specs. In my experience Mantra is very similar to renderman.

Other than that, ask sesi directly?

[eetu]

Possible reasons for unfamiliar numbers:

- you have rotation before translation in your transformation order, so if you first rot 45 degrees and then move (10, 5) you do not end up in nice integer coordinates

- the rot values are in radians not degrees

[edward]

This was answered on the sidefx forum.