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Houdini Vex Lit Fog Behaviour And Scene Size


Fomal

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Hi People,

I recently made the switch from Maya to Houdini and am finally getting some work done! Love the node based structure and the control you get. I've got everything set up to render but there's one problem regarding the volumetric pass. I did a camera match to my background plate and as a result of that my entire scene got a lot bigger in terms of geometry. That's no problem for lights etc. but my volumetrics in conjunction with the spotlights i've set up don't seem to work properly. I've spend numerous of days trying to find a solution. Using 3d textures, fluid containers and some volumetric shaders. No result at all.

The problem I run in to with the VEX LIT FOG is that it does behave okay further away in the scene but as the object moves closer (so does the light attached to it) the fog seems to dim and even disappear near the camera. I just can't get my head around this. The other way around it's the same. If I adjust the LIT FOG settings to behave properly close to the camera it appears way to bright if the object is in the back of the scene.

I've also tried the ISOOFFSET en ISO node. Using these to form a basic outline for a 3d texture or fluid works okay in smaller scenes and example files but gives me just a black render in my own scene. This is after I scaled it and adjusted the settings to work with the scene I got. It least, that's what I think I've done.

So is there an easy way of scaling my entire scene without losing my camera settings? Or is there a way to get the volumetrics working with the scene I got? Any help would be greatly appreciated! I'm totally stuck and have no Idea how to fix this in Houdini.

I Included my scene for anyone who would like to take a look at it. It can be found here: click

BTW: This is my first post and I hate starting of with a question but since i'm an Houdini noob i hope someone can help me...

Cheers! :ph34r:

Edited by Fomal
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Quick update,

managed to scale my scene down using collapse sop and parented the spotight to the object that has to emit the beam of light.So I collapsed everything except the object where the spotlight has to be parented to. This object is a child of the collapse node so I could scale everyhing down at once. Including the camera.

At first this looks okay. Camera translates perfect but the light fog doesn't work at all. This gives me all sort of weird results when it renders like a total black and white image or a partly lit image with a weird fog distribution and no fog on the black parts of the alpha. So i'm keyframing the fog settings now (step size, intensity etc.) to match the fog when the objects in the back of the scene and adjust it as it moves forward. Using my old scene settings.

But my question's still there. Isn't there an other way in houdini to set up volumetric light? Without havng to resort to code or this shader? :blink:

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