Messages

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[C4D] General Discussion / Re: Why Corona render GI diffuse is much weaker than other Renderers ?!

« on: 2023-09-04, 14:33:22 »

I dont think you can conflate exposure and tonemapping settings with gi depth in a scene like this TBH. No-one expects the default tonemapping and exposure to match between different render engines. A feew small tweaks in the VFB and you could match pretty easily IMHO.

I disagree, because
- If there is interference by tweaking in the VFB (except exposure ), or composition, this will no longer be fair.
- Even if you make adjustments in VFB or composition, 2D-based adjustments cannot have the same impact as light transpot algorithms for 3D. For example, when you try to adjust contrast and brightness to brighten dark areas. This affects the entire image, and makes the parts appear washed out and stuck together, ugly and unnatural, while the darkest areas remain dark. Normal areas and highlights are neutralized together. Also, it creates stains and noise from those dark areas. This is far inferior to images produced by pure raytracing algorithms.
Anyway, my purpose in this post is fulfilled, which is to find the error of ACES, thank you for that. :D

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[C4D] General Discussion / Re: Why Corona render GI diffuse is much weaker than other Renderers ?!

« on: 2023-09-04, 12:40:26 »

Sorry but theres clearly something wrong with your setup.

I copied the scene into a new file, and the default result from corona is attached (left with default tonemapping including aces ot, right with the aces ot turned off). Take a look - it doesn't replicate whet you showed.

Edit - I see that you set your exposure to -2.8 in the VFB. But replicating that still doesn't create the harsh blacks shown in you example. It actually looks pretty much as per the v-ray version you attached unless you have the aces transform turned fully on. This sems to be a tonemapping issue not GI.

 So I confirm that this is error issue with ACES tone mapping. After the turn off ACES, even though its scattering is still not as deep as V-ray level, but it looks a lot better than the previous version.

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[C4D] General Discussion / Re: Corona render lack so much GI

« on: 2023-09-04, 05:49:10 »

Corona has one of the best GI i know from the current render apps.

Vray has more bounces per default(100) thats true, but when rendering Corona interiors one see the default 25 bounce in Corona produces a similar if not better look.
(by the way vray at 25 bounces looks also same as vray with 100 bounces. so it seems the extra bounces have only minimal effect)

from your tests you seem to use a very different tone mapping than for the others, and it seems you yet miss some knowledge on corona setup (see your leave material)

best as Dave said share your scene;)

No, it's not. Corona only look good if it don't put beside V-ray. In this particular case. As you can see, V-ray is the real best renderer for tree scenes. Its deep scattering light through the foliage very evenly and that make the scene look very dreamy and fanciful mood. Corona is not beautiful like that, its contrast not good at all, its GI itself is also lost.



I update some more renderers result of the post. Actually, all the shaders of Corona are weaker than other renderers in both quality, speed and memory using. But on this post, I only start with diffuse, the next post would be volume, SSS, hair, transparency, performance, workflow and manything else.

If you want files, I have .c4d ( + fb and alembic ) files : https://drive.google.com/file/d/1brgvBp2l0843Z3oIqomoZy_890VyJWhy/view?usp=sharing
 But I guess you've only used 3DSMAX and never used c4d. So I will talk about the parameters for you to set up yourself. For the comparison to be unbiased, the conditions for consistency between the software are:
1. Keep the original input texture
2. Always set fraction value of translucency at 55%.
3. Tweak the light so that the color and brightness of the translucency color and direct diffuse match the V-ray render image :
4. do not use any LUTs

The remaining thing is to admire the difference in indirect diffuse between the two or more render engines

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[C4D] General Discussion / Why Corona render GI diffuse is much weaker than other Renderers ?!

« on: 2023-09-03, 12:03:26 »

I think this is both problem of energy loss and  problem of the core GI algorithms.
Actually, All the shader of Corona have problems, but in this post I will start with Diffuse GI lacking. I wonder if the developers will rewrite the core in the future?

On this images below, only 1 direct light ( sun ). other renderers have much more wide GI range.

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[C4D] General Discussion / Re: Realistic VDB cloud

« on: 2023-02-23, 17:51:02 »

Hi all, thanks for the discussion and examples. We understand that cloud rendering (and volumetric scattering in general) can work differently in different renderers. Some improvements are possible in Corona, but at this point we do not think they are critical to Corona development (creating ultra-realistic clouds / volumetric effects is not so common among Corona users).

If I am not mistaken, the realistic-looking clouds with strong silver lining or the darkening effect would require what we have already logged as a feature request under "blending several phase-functions in a single volumetric material".
Currently, you can create with Corona a volumetric material which has uniform scattering (same scattering towards and away from the light source), forward scattering (more light is scattered further from the light source than bounced back into it), or backward scattering (more light is bounced back into the camera than passes further). This is controlled using the directionality parameter. What is currently not possible is blending those behaviors in a single material (e.g. a material which would have +0.9 and -0.9 directionality at the same time and this would be blended together) or using some special "curves" to define the scattering.

(Internal ID=1060972842)

Thanks so much for replying. I still think that this should be improved in both speed and behaviors ( using blending like you said ). It may not be a priority right now, but I truely hope it won't be a long delay. Because today's renderers are all very advanced and users are always demanding more and more for quality and volume is a very important thing.

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[C4D] General Discussion / Re: Realistic VDB cloud

« on: 2023-02-18, 03:12:22 »

If you use the density channel for scattering you are basically diminishing it where the density increases - while it gives you some additional artistic control, it's technically wrong. Scattering should be a constant color, and then play around with the value - it has a ceiling value where it won't change with increased values. It should produce a better result.

I always set scatter to 100% white, no channel at all. So, please take it seriously and accept that Corona volume is not deep scattering enough for cloud.

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[C4D] General Discussion / Re: Realistic VDB cloud

« on: 2023-02-17, 17:38:22 »

well, here a fast try i just did.

nothing special of course, but i think scattering is not so bad i feel, and even renderspeed also is ok (i raised step value a bit to make it faster).
the scale value is most important in my experience, so it fits the size of scene and cloud.

You can see that there are still dark inner of your cloud. Due to weak scattering. And that will be even worse when you increase thickness of the cloud

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[C4D] General Discussion / Re: Realistic VDB cloud

« on: 2023-02-17, 16:22:32 »

I've tested the Moana cloud some times ago in Corona (for Max), and while it was slow - I agree - it looked quite good.
There are a couple things to keep in mind for a fair comparison. Do you have similar phase function settings across all renderers? This is one of the most deciding factors for how realistic rendered clouds will look. The 0.5 value in Vray's examples will be typically too low to generate dark edges, a more realistic value is in the range of 0.7 to 0.9.

Corona's performance tanks once you use higher values for the phase function (positive values mean forward scattering) and it'll be quite slow for values close to 0.9 - generally increasing this value will result in slower rendering since way more samples are needed to resolve the scattering within the cloud.

Another factor is how many bounces you use. Corona's default will be way more than most renderers. However for a realistic result you'll need to go even higher.

Also... what's the 'other renderer'?

Ofcourse I set all of them is 0.7 at directionality.  Depth ray = 100. Butafter many tests i have to admit that the light passing through corona cloud is not deep enough to form cloud shading

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[C4D] General Discussion / Re: Realistic VDB cloud

« on: 2023-02-17, 11:06:57 »

Hi there,
Could you please provide some examples of your work and the result you're looking for?
This to better understand the issue.
Kind regards.

Hi,
Would you mind to report this to dev team?
Please !

10

[C4D] General Discussion / Re: Realistic VDB cloud

« on: 2023-02-16, 14:35:16 »

Hi there,
Could you please provide some examples of your work and the result you're looking for?
This to better understand the issue.
Kind regards.

Thanks for reply.

11

[C4D] General Discussion / Re: Realistic VDB cloud

« on: 2023-02-16, 14:15:45 »

i can't talk about the speed, i havent yet compared with v-ray,
but the scatter phase feature you linked is also in Corona Render (forard/backard scatter value).

Not at all, prove it if I'm wrong.

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[C4D] General Discussion / Re: Realistic VDB cloud

« on: 2023-02-15, 18:29:20 »

Nice render, but my post mean to create dark edge and deepscatter, only with sunlight

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[C4D] General Discussion / Realistic VDB cloud

« on: 2023-02-15, 17:36:03 »

I noticed that Corona dev has no intention of improving the multi-scatter of volume rendering in Corona - very important feature, which V-ray 6 has done very well, the latest version of V-ray allows realistic cloud rendering ( with deep scatter and dark edge ) with fast render times. I hope the developers can focus on this

https://docs.chaos.com/display/VMAX/Smoke+Color+Rollout?preview=/60098786/82300631/forward.jpg

https://docs.chaos.com/display/VMAX/Smoke+Color+Rollout?preview=/60098786/82300634/ForwardScattering_2_diagram.jpg

Thanks !