OTOY Forums

Hello

I am trying pyro render your latest plug in , on version h15.0.459

setup:
basic explosion sim from houdini shelf
add object property and turn on volume render on pyro import
create material medium scatter plus blackbody emission
set the material

Issues:
Renders only smoke (as if temperature isnt considered)
Render target has no volume option.(pathtracing)
Sometime renders blue flame, and emission node temp doesnt change anything
I also get an error:
*** OCTANE API MSG: Tried to access attribute via invalid ID A_VOLUME_VELOCITY_OFFSET_START (232)
*** OCTANE API MSG: Tried to access attribute via invalid ID A_VOLUME_VELOCITY_OFFSET_START (232)
*** OCTANE API MSG: Tried to access attribute via invalid ID A_VOLUME_VELOCITY_OFFSET_START (232)
*** OCTANE API MSG: Tried to access attribute via invalid ID A_VOLUME_VELOCITY_OFFSET_START (232)

i love your plugin but the lack of tutorial/explanation is stagering.
I found a tutorial (quicktip on vimeo) but it is outdated as the plug in had interface changes

The kernel nodes don't have now the volume step option, this feature is now available in the volume medium node, that is the node that you should use to render the volume objects. I will try to post a sample scene ASAP.

From the release notes:
- Moved the volume step length from the kernel node to the volume medium node. This allows you to tweak the value for each volume and depending how close and how big they are.

Anyway, the Octane API MSG can be a bug in the plugin. Let me check this problem and the other issues you have.

Thanks,
-Juanjo

thank you juanjgon

You can ignore the Octane API MSG. I will fix it for the next build, but it doesn't mean any problem for the volume rendering.

-Juanjo

ok, but i still cant render fire for some reason.
depending on the shelf preset i use, i either get simple smoke or some weird blue fire

Attached you have a Houdini volume object sample scene and some screen grabs about the settings used. I will update all the plugin docs with all the new Octane 3.0 features along the next weeks

Thanks,
-Juanjo

One important trick to render emissive volumetrics is to disable the "Normalize" option in the emission node. Also be aware that the emission temperature is extracted from the emission grid, this is why we must scale it in the OBJ spare parameters. I am using the heat grid for the emission, not the temperature one.

-Juanjo

thanks a lot juanjgon.

So the only issue was scaling temp from obj node and use heat instead of temp



u made my day

thank you

I find it a bit daunting to play around between the obj heat value and the power fo the shader
But the result is there

thanks for your help

Fred

Really nice!

-Juanjo