Slow rendering with materials

[Bpositive]

Hi

Just began testing Corona render and thought it was quite slow when testing some interior and exterior shots.

When I use a override material the render is about 10x faster. - It's not exactly simple shaders and textures I have converted from vray, but still it seems too slow on my 2x 8 core cpus.

I have adjusted the rendersettings for faster results and also avoided very bright materials.
Also having absorption in glass seems like a very bad thing.

What are your thoughts on this? - thanks a lot.

[maru]

Here we go again. :)

-What kind of glass are you using?
-How is the lighting made?
-How is the background image added?
-What are your render settings?
-Are you using multi/sub-object materials anywhere?

Also, did you try overriding material only on some of the objects? For example on the reflective floor? Does it speed things up?
To me, this looks like reflective or refractive caustics' fault but I'm not sure.

[Juraj]

I would echo what Maru said. The noise seems very "causticky", as it contains lots of specles. Did you keep default MSI ? Is the glass without caustics ?

Outside of that, 5 minutes is not a lot, 2630v2 is not extremely fast CPU either but yeah the issue might probably be in the setup rather.

[Bpositive]

Thanks guys for the fast replies.

-What kind of glass are you using?  Very simple and no caustics & absorption.
-How is the lighting made? It's vrayhdri map in the corona env map.
-How is the background image added? also through the corona env map
-What are your render settings? See image - PT + PT, I know the hd cache would be faster. MSI is default.
-Are you using multi/sub-object materials anywhere? Yes quite a few, is that a problem...!? :-(

[Juraj]

Ok.

Well, I wouldn't rise light samples at all, I use HDRi for 90perc. of my jobs and I only rise LS for interiors with lot of artificial lights. You will still fight mostly GI and AA.
PT+PT for glossy interior is really bad choice, HDCache outside of GI, also helps with glossy materials. You can use it, but it will take hours, and will give negliably only better image.

I have no idea about multi-sub mats, I am interested too in that.

[Bpositive]

Thanks

Guess I just need the same renderfarm as you Juraj :-) - and some more patience ;-)

[Juraj]

Thanks

Guess I just need the same renderfarm as you Juraj :-) - and some more patience ;-)

Well that always helps, but if there's issue it's better to troubleshoot it first :- ).

Generally, with default settings (everything not touched), 100 passes is mostly enough to clean both AA and GI for interior, esp. one so open like yours.

[maru]

Thanks guys for the fast replies.

-What kind of glass are you using?  Very simple and no caustics & absorption.
-How is the lighting made? It's vrayhdri map in the corona env map.
-How is the background image added? also through the corona env map
-What are your render settings? See image - PT + PT, I know the hd cache would be faster. MSI is default.
-Are you using multi/sub-object materials anywhere? Yes quite a few, is that a problem...!? :-(

But does the glass have thickness?
Can you try hiding window glass and see what happens?
I would suggest using PT+HD.
Reset light samples multiplier to 1 or 2.
If MSI is at 25 then it's not default. It should be 20 but it's a tiny difference so we can just ignore it.

About the multi/sub materials, I remember there were some problems with them. Especially when there are things like mixed glass-nonglass faces. This would probably require some more research.

Some of the noise could also be caused by this:
https://forum.corona-renderer.com/index.php/topic,5628.0.html
In this case I think background works like light. That's why I pointed this as a really serious issue.

I can also see your glass has diffuse colour. Set it to 000 black or set diffuse level to 0.

[Ondra]

can you post screenshots of both images with the full VFB (with sidebar) - I am interested in the statistics. It seems that the one with material has much higher rays/sample value.

[Bpositive]

Just rerendered with updated settings as suggested by Maru.

Yes, the glass has 20mm thickness.

[Ondra]

can you also render the albedo pass? Are you using any blend materials, ambient occlusion, or rounded corners?