bryce volumetric clouds

Fhalo

Hello

Thanks again for help & advice on how to create the perfect sunrise/sunset.

My next problem is bryce volumetric clouds.

I estimate that it will take upto ten days on my quad PC to render a simple sunset scene, at 1080 resolution, using
volumetric clouds.

Is they a way to reduce the render time and still produce great clouds?

David Brinnen

Fhalo said:

Hello

Thanks again for help & advice on how to create the perfect sunrise/sunset.

My next problem is bryce volumetric clouds.

I estimate that it will take upto ten days on my quad PC to render a simple sunset scene, at 1080 resolution, using
volumetric clouds.

Is they a way to reduce the render time and still produce great clouds?

Yes, many ways.

1 - lowering the quality setting of the volumetric material will reduce render time.
2 - reducing the thickness of the slab the material is applied to will reduce tender time.
3 - careful control of lighting.

Be aware shadow intensities of under 100% will impair the rendering of volumetric materials.
Also, any soft shadows on light sources present will severely impact on render times.
If HDRI backdrop is used. Make sure there is 0 output in diffuse or specular channels.
If additional light sources are used, and even if the slab is excluded from their influence, this will still have an impact on render time.

Also...

If you can cover up the horizon in some way that blocks off the rendering of that portion of the sky (distant mountains for example), this is highly beneficial to rendering.

Furthermore...

Altering the AA render tolerance can help considerably. Default is 15 but this can be raised much higher without a negative effect on the appearance of volumetric clouds. Look in Render Options menu on the right hand side to find AA tolerance control.

Edit, this final option only works for regular rendering mode, and only affects the AA pass, so it will not have any impact on the predicted render time. But it will have an impact in real terms.

Fhalo

Thanks again david. I'll experiment with your suggestions.

I did uploaded my first attempt at doing a sunset to 'Show Us Your Bryce Renders! Part 2'

I've still got alot of work to do.

David Brinnen

Fhalo said:

Thanks again david. I'll experiment with your suggestions.

I did uploaded my first attempt at doing a sunset to 'Show Us Your Bryce Renders! Part 2'

I've still got alot of work to do.

Just looked through 'Show Us Your Bryce Renders! Part 2' - but I couldn't find it. Can you give us a clue, what page is it on?

Fhalo

Upload it again.

Forgotten to do preview.

Still got alot work to do.

Thanks. You advice about reducing the thickness of the slab works. It had taken few minutes to do 1% render whereby it was taking hours.

Would the thicknes of the slab reduce the quality of the cloud?

Dave Savage

Fhalo said:

Would the thicknes of the slab reduce the quality of the cloud?

No, but reducing the slabs thickness does obviously make the volumetric cloud layer thinner.

Another thing I've found is that making the slab a lot lower than you think it should go helps reduce rendering times too. No good for a 3D animated scene, but ideal for a static render as long as it looks optically correct from the render cameras PoV.

David may correct me on this but I don't think that 'Maximum Ray Depth' has much effect on clouds so reducing that from it's default 6 down to 3 or even 2 (in the Render Options window) can decrease render times. I think the main problem in your situation is that it will impact on the reflectivity of the water.

David Brinnen

Dave is quite right - I did forget to mention the maximum ray depth. Default setting is 6. For TA renders I usually go for 4. For clouds and a simple water surface you can get away with 3. Every bit helps.