Flask

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filip
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Flask

Post by filip » Sat Sep 14, 2019 10:11 am

flask6.png
Using the latest version for Blender 2.8

Bidir + Metropolis on Ryzen 3900x.
I let it render for about 50 minutes and then denoised with the Intel denoiser.

If anyone wants to look at the file, I'd appreciate it. Here is the file:
https://gofile.io/?c=coEwtF

Basically I'm interested if I have the "liquid in container" setup up correctly. I'm not sure I understand exactly how to set up the volumes and priority. I also had to move the flask above the ground floor a bit, otherwise the bottom showed up gray. I mean, not only if the bottom shared the same space with the floor (which makes sense that won't work correctly), but even if it was just slightly above it. There seems to be like a cutoff point where the gray doesn't show up anymore. Though it's still under 1mm so I guess that's fine.

And are there any optimizations I can do to make the noise clear faster? The glass was still very noisy when I stopped the render and the denoiser does an amazing job, but I'd still like to know if there are things I can improve.

Thank you.

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B.Y.O.B.
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Re: Flask

Post by B.Y.O.B. » Sat Sep 14, 2019 10:36 am

Nice result!
filip wrote:
Sat Sep 14, 2019 10:11 am
Basically I'm interested if I have the "liquid in container" setup up correctly.
There's an example here: viewtopic.php?f=4&t=728#p7550
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Sharlybg
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Re: Flask

Post by Sharlybg » Sat Sep 14, 2019 11:00 am

Normally hybrid should be a lot faster.
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filip
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Re: Flask

Post by filip » Sat Sep 14, 2019 11:33 am

What do you mean by hybrid?

If you mean CPU+GPU it seems I can only use one or the other, but not both? Also looking at other posts around here I understand Metropolis is not recommended on the GPU?

Edit: Actually, I think I can't use the GPU at all with Bidir.

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lacilaci
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Re: Flask

Post by lacilaci » Sat Sep 14, 2019 11:45 am

filip wrote:
Sat Sep 14, 2019 11:33 am
What do you mean by hybrid?

If you mean CPU+GPU it seems I can only use one or the other, but not both? Also looking at other posts around here I understand Metropolis is not recommended on the GPU?

Edit: Actually, I think I can't use the GPU at all with Bidir.
If you use opencl build then you can use gpu + there is a lighttracing option in render settings
This will allow you to use gpu for pathtracing and cpu for lighttracing part (bidir without MIS) this is hybrid rendering and it is much faster than normal bidir...

And yes, don't use metropolis when rendering on gpu (lighttracing will "under the hood" still use metropolis though, but you don't need to care about that)

filip
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Re: Flask

Post by filip » Sat Sep 14, 2019 11:59 am

So you mean the settings like this?
test.png
Trouble is, like this I'm not getting that cool caustic ring in front of the flask.
And also the bottom of the flask is reflective.
I'm not sure which is the physically correct one now. :)
Last edited by filip on Sat Sep 14, 2019 1:11 pm, edited 1 time in total.

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lacilaci
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Re: Flask

Post by lacilaci » Sat Sep 14, 2019 1:07 pm

filip wrote:
Sat Sep 14, 2019 11:59 am
So you mean the settings like this?
test.png
Trouble is, like this I'm not getting that cool caustic ring in front of the flask.
And also the bottom of the flask reflective.
I'm not sure which is the physically correct one now. :)
Yup, that looks wrong, not sure why. Probably Dade should take a look at that.

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Dade
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Re: Flask

Post by Dade » Sat Sep 14, 2019 2:19 pm

lacilaci wrote:
Sat Sep 14, 2019 1:07 pm
Yup, that looks wrong, not sure why. Probably Dade should take a look at that.
Both Path a BiDir produce the same result if I render the water alone:

water.jpg

As soon I add the glass, the results differ, this is Path:

path.jpg

while this is BiDir:

bidir.jpg

Path shows the reflection of about the top of the HDR image, while BiDir shows a different region. This happens because the volume is not correctly set up and you have different refraction angles: you have a lot of coincident surfaces (i.e. water/glass, glass/floor, etc.), the results depends on many factors as the numerical precision and if tracing light from camera or light sources (i.e. a ray may hit first the water or the glass and have different refraction/reflection angles).

You have to set up the volumes as explained by B.Y.O.B. so a ray will always hit the glass before the water:

Image

P.S. you may still have numerical precision problems because your glass is very thin but that is a different kind of problem.
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Re: Flask

Post by filip » Sat Sep 14, 2019 2:31 pm

I set them up like that (or at least I think I did) and still getting different results.

Would you mind setting it up and uploading the scene? You can remove the embedded files if you want so reduce the file size.

And what do you think about the caustic ring I mentioned above? I'm guessing that's not possible with Path?

Thanks a lot!

Edit: I appended the materials from that scene that B.Y.O.B. linked to and still the same different results with the 2 engines.

filip
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Re: Flask

Post by filip » Sat Sep 14, 2019 10:40 pm

OK, I think I figured out what the problem was. I moved the liquid further into the glass and then the Bidir render looked the same as the Path one. So that must be the correct look. Well, I double-checked with the real object too. :)
However, I didn't like the reflection on the bottom of the flask so I made a studio like setup to block it.
Here's how it looks now, still rendered with Bidir:
flask7_3.png
So now one question remains, if there is some way to get those caustics (on the right side) with Path.

Anyway, thanks a lot to all of you for the help. This is an awesome render engine, I haven't had this much fun playing around with graphic software in a long time. I hope you keep developing it.

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