caustics not rendering when camera is scaled

[pclaes]

Hi,

I just wanted to post this as a bit of information if anyone else would come across this problem:

I have a null object in the scene with a camera parented under the null. The null is scaled up 70 times and the camera has keyframes on the translation and rotations.

Shooting photons works fine and you can see them in the scene, you can render them using PBR with a normal camera, but for some reason I just could not get the caustics to render with the parented camera. It was driving me crazy.

I should have known it was the scaling, scaling cameras is generally not a good idea.

So I object merged the origin of the camera into a new geometry object and extracted the translation information with a point() expression. This gave me the translation information I needed which I then fed into the translation information of a new null. I copied the original camera and parented it under the newly created null. With no scaling in any of its parent nodes the caustics would finally render.

Maybe I am missing something straightforward, but that was how I solved it. Hopefully it can be of help to others in the future.

Another little note I wanted to add is when you just want caustics and nothing else, make sure that when all the lights are disabled you add the soho_autoheadlight rendering property to the mantra output driver from the edit parameters interface. For more advanced users this might have been easy to find, but it took me a while to figure out it was not something like: "mantra -n 4" in the render command field. But that instead you actually have to (and can) add other rendering parameters through the edit parameters interface (the little cog in the upper right hand side). Otherwise houdini will just add a "default" light to the scene.

Edited April 10, 2008 by pclaes