LuxCoreRender Forums

provisory wrote: ↑Wed Aug 14, 2019 6:47 pm My version:
juice.jpg

Only lit by Sun + Sky.

ok, so it almost looks correct once you put sun low cause there's lot of diffuse lighting and weak directional, but you start moving sun around and it clearly doesn't enter the volume directly.

here's your scene with sun blasting right from above, this looks all kinds of wrong this is in my scene near a proper looking volume (architectural glass) So yeah, I'm thinking that luxcore doesn't do transparent shadows for glass, it's always black for direct lighitng so you can never shoot direct lighting through glass.

wasd wrote: ↑Wed Aug 14, 2019 9:31 pm juice_sunsky.blend (with volume priorities and ior fixed)
Path+Sobol jupa.png~
Bidir+Metropolisjubi.png~
I like bidir version better. It is three times faster and ten billion times better.

Do you really find this proper looking?

wasd wrote: ↑Wed Aug 14, 2019 9:07 pm Your volume priorities are also both 0.

You're right. (I should have mentioned, that mine was based on Sharlybg's.)

lacilaci wrote: ↑Thu Aug 15, 2019 4:55 am here's your scene with sun blasting right from above, this looks all kinds of wrong
juice_sunupprovisory.png

Some more changes and corrected volume priorities.
Oh, and I had to increase path depths!

Sun is directly from above:
Sun from behind (like on pleasing shots):

provisory wrote: ↑Thu Aug 15, 2019 5:58 am

lacilaci wrote: ↑Thu Aug 15, 2019 4:55 am here's your scene with sun blasting right from above, this looks all kinds of wrong
juice_sunupprovisory.png

Some more changes and corrected volume priorities.
Oh, and I had to increase path depths!

Sun is directly from above:
juice3.jpg


Sun from behind (like on pleasing shots):
juice4.jpg

Ok, so first of all using semi transparent glass is the worst fake possible, it's a game engine level of fake and while I love biased renderer fakes this is often gonna be super wrong looking in some cases.

In your case it somewhat works as we cannot observe any shapes behind glass to be able to tell it's actually 10% transparent but even I "lover of fakes " would not accept this solution (I did this in past with luxcore and it's just horrible looking glass in many cases)

Second, the increased bounces give a little more bounce light to the volume but won't ever compensate enough for the lack of directional light especially when you blast full power sun through the glass.

here in my renders you can see left to right - your solution, actual 100% solid glass, and juice body without glass using architectural option so that no shadow is cast on volume on the rightmost juice you clearly see the gradient from directional light, on middle one there is none and on yours there is a small hint of it cause the glass itself is transparent but the juice isn't archglass so the top of it looks super dark just as in the middle...

lacilaci wrote: ↑Thu Aug 15, 2019 6:39 am Ok, so first of all using semi transparent glass is the worst fake possible...

Semi transparent glass was just a test, I left it like that by accident.

I suspect, that SDS paths have a big impact here, so here is a render with corrected glass opacity but with BiDir Metro:
(eye and light paths both set to 20)
Please take into consideration, that these are transparent, translucent and reflective materials, so environment is very important here. For example the gradient of the middle glass in your image was effected from the two other next to it.

Edit: ...and the color/brightness highly dependent from the background!

lacilaci wrote: ↑Thu Aug 15, 2019 5:02 am Do you really find this proper looking?

I never said I find it proper looking.

I suspect, that SDS paths have a big impact here, so here is a render with corrected glass opacity but with BiDir Metro:
(eye and light paths both set to 20)

BiDir can't do sds, even with metropolis it fails, and if we add volumes it get's even worse..
I generally don't like bidir at all, it's just terrible and slow... There are better and faster solutions and I think Dade is on a good way to getting them to luxcore

Please take into consideration, that these are transparent, translucent and reflective materials, so environment is very important here. For example the gradient of the middle glass in your image was effected from the two other next to it.

No, not really. All three glasses are directly exposed to sun so all volumes should be lit as well

Edit: ...and the color/brightness highly dependent from the background!

it only adds bounce light in your case, so things seem brighter but that's all

The only thing that really can do it currently is caustic cache (and I'm not even sure that it is doing it right either)
But no one will ever use this in production, it's pain to setup and it's slow and only God or Dade knows if it can even converge to an acceptable result in thousand years.

EDIT: I left it rendering.. and it actually looks like caustic cache is just putting caustic to the volume but still no sunlight gets through glass it seems.

I think we gonna need lighttracing+VM+transparent shadows and everything will be correct and fast.

My latest juice volume:
And some renders with hdri lighting (BiDir + Metro):

HDRI 1. front HDRI 1. back HDRI 2. front HDRI 2. back

provisory wrote: ↑Thu Aug 15, 2019 11:15 am My latest juice volume:
juice9-volume.png


And some renders with hdri lighting (BiDir + Metro):

HDRI 1. front
juice9-hdri1-front.jpg

HDRI 1. back
juice9-hdri1-back.jpg

HDRI 2. front
juice9-hdri2-front.jpg

HDRI 2. back
juice9-hdri2-back.jpg

But now you changed condition and you're rendering with hdri, this isn't solving anything