Improving speed with BF+LC?

[Alex_M]

I've been trying to use BF+LC for a job here because of the nature of the lighting in the interior which is too complex for IM to render properly without splotches and defects. Unfortunately it renders a bit slower than I would like. I made a test with Corona and it seems that it rendered the image with noticeably less noise for the same amount of time (4 minutes). My vray settings were at their defaults - BF+LC, progressive sampler 1/100 subd. etc... the only change in the settings was that I disabled probabilistic lights (it produces some defects and different light intensity).

Here are the results:
Is there anything I could do to match the noise level of Corona?

[^Lele^]

Do you have a scene i could look at?
You can send it to my chaos email, if you can't share it here.
Besides render settings, a number of things may not be exactly equal in shaders and/or lights, as not all features map 1:1 between the two.

[vlado]

Yes, it would be best if you can share a scene. Looking at the ceiling lights though, can you explain what kind of light sources they are? They seem a lot noisier than they should be.

Best regards,
Vlado

[Alex_M]

Yes, I will pack up the scene in both versions (corona and vray) and will send it to you. The ceiling light is a vray mesh light.

I forgot to mention that the corona scene was created from the original vray one by using Corona Converter. I haven't bothered recreating the materials from scratch as I don't have the time.

Do you have a scene i could look at?
You can send it to my chaos email, if you can't share it here.
Besides render settings, a number of things may not be exactly equal in shaders and/or lights, as not all features map 1:1 between the two.

Can you kindly let me know your email address? Thanks.

[^Lele^]

emanuele.lecchi at the usual chaos domain

[^Lele^]

I forgot to mention that the corona scene was created from the original vray one by using Corona Converter. I haven't bothered recreating the materials from scratch as I don't have the time.

hihi, that was what i assumed, and am most curious to see what that did.

[Alex_M]

Thanks, Lele. I just sent you an email with download link.

[vlado]

Thanks for the scene, Alex - looking into it now.

Best regards,
Vlado

[Alex_M]

Awesome, looking forward to finding out if it can be faster. Irradiance Map just can't handle this scene well with all the light sources and geometry, particularly the slatted ceiling.

On a side note, I'm finding that I get splotches/uneven lighting in the slatted ceiling even with BF as primary engine. Is this supposed to happen? :/ Secondary engine is LC 3000 subd. world scale (2.5 cm), prefilter 20 and interp. samples 5. I had to resort to using BF+BF around the slatted ceiling to make the splotches go away which goes without mentioning that it's slooooow. Any other way to clear these splotches without using BF+BF? I'm not trying to sound as a corona fanboy but I found that corona gets the slatted ceiling splotch-free even when the secondary engine is the biased UHD Cache (which I think equates to Light Cache in Vray?).



Can one get away with BF+LC if they want no splotches or BF+BF is the only solution at the moment? Just putting this out there for constructive dialog to find out if there's something that I'm missing or if something can be improved.

[vlado]

Increase the subdivs for the light cache and, just in case, reset the V-Ray settings and the splotches will usually go away.

Best regards,
Vlado

[vlado]

Btw these are my results so far for a simplified version of the scene; it looks like I have some issues with sampling the mesh lights, which I'm currently looking into.

Other than that, the VRayLightMtl that is inside the multi-subobject material for the "Spotlight NNN" objects is causing a lot of noise because V-Ray can't sample it properly. The material is called "Material #2097630153". I'm not sure what was your intention in creating this material? Do you want it to be an actual light source? You already have true V-Ray lights in there, so unless you specifically wanted noisier renders, I'm don't see it's purpose...

Best regards,
Vlado

[vlado]

Here are more accurate renders (I had some object hidden in the Corona version above). In this one you can also see splotches on the ceiling in the Corona version.

It looks like if I can fix the fireflies from the mesh lights, we'll be good to go...

Best regards,
Vlado

[Alex_M]

Thanks for the info. I had a feeling mesh lights are at fault here. I posted a thread about this several days ago, I'm not sure if you saw it.