[Sidefx-houdini-list] reversing camera track

Andy Nicholas andy at andynicholas.com
Wed Jan 4 01:54:22 EST 2017


At the moment, you have an animated world->object transform for the object. If your camera is at the origin with no rotation (and if it's not then it's probably a good idea to do so), then this also happens to be your camera->object relative transform.

To have your camera move around instead, you want to invert the animated camera->object xform and apply that to the camera, which will become an animated object->camera xform. You can then place your object at the origin to get you the desired result. The camera transform is then equivalent to a world->camera xform which is what you want. 

I'm not in front of Houdini at the moment so I can't test out the best way of achieving this unfortunately, but that's the basic principle. Going through CHOPs to a duplicate camera and object is probably the best bet so you can keep it live. 

Cheers,
Andy

> On 4 Jan 2017, at 09:15, Gary Jaeger <gary at corestudio.com> wrote:
> 
> Scratching my head on this. I have an object track with static camera but I’m trying to reverse the motion to have a static object and moving camera. The math eluding me. 
> 
> Gary Jaeger / 650.728.7957 direct / 415.518.1419 mobile
> http://corestudio.com <http://corestudio.com/>
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