motionprojects Posted April 3, 2011 Share Posted April 3, 2011 I don't know the technical term for this, but I'm calling it a '3D pin of the camera' Let's say I have a scene with grid, sphere, pyramid, box etc. Then we keyframe a camera to navigate the scene. The end result I want is: what we see through the camera is exactly the same, only it is the camera that is still, and the scene is doing the rotation and translation. Is this solved through transform expressions, chops? python? Thanks in advance for any guidance. Quote Link to comment Share on other sites More sharing options...
brianburke Posted April 3, 2011 Share Posted April 3, 2011 The end result I want is: what we see through the camera is exactly the same, only it is the camera that is still, and the scene is doing the rotation and translation. howdy, this is pretty chill to do in houdini. i'm sure there are lots of ways to do this, but i always find vops the easiest way to deal with matrix stuff. this example shows grabbing the camera xform with a vop sop and inverting it, then using a point expression to animate a null with this xform. if you parent all the objects in the scene under this null, they animate around the origin. inverse_camera_xform.hip Quote Link to comment Share on other sites More sharing options...
motionprojects Posted April 4, 2011 Author Share Posted April 4, 2011 Thanks so much. May be the odforce be with you. Time to dig into vops matrix experiments. Quote Link to comment Share on other sites More sharing options...
doc Posted April 5, 2011 Share Posted April 5, 2011 you can use an object merge as well. specify your camera in the object transform and it will orient the scene along the -z world axis (as if your camera was pointing down the axis). works like a charm 1 Quote Link to comment Share on other sites More sharing options...
kgoossens Posted April 6, 2011 Share Posted April 6, 2011 (edited) you can use an object merge as well. specify your camera in the object transform and it will orient the scene along the -z world axis (as if your camera was pointing down the axis). works like a charm Can you also do the perspective transform? So it would flatten the scene to a plane with perspective distortion? Oops this is easy http://en.wikipedia.org/wiki/3D_projection Edited April 6, 2011 by kgoossens Quote Link to comment Share on other sites More sharing options...
dvfedele Posted March 13, 2013 Share Posted March 13, 2013 What if the object/camera wasn't animating at the obj level and rather on the sop (per point) level? I'm trying to do the same and get the transforms/rotations on geometry imported from maya. Quote Link to comment Share on other sites More sharing options...
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