V.Ray and Corona - how to Reach a matching shading level ?

[majid_shatnawi]

Based on this article: https://support.chaos.com/hc/en-us/a...%20properties., Corona enables us to obtain more realistic lighting and shadows than V-ray, which is obvious by practical trials. Then, what are the modifications that boost V-ray results up to the level of Corona results, away from any editing the render's results in the post-production stage?

best wishes.

[Vizioen]

Based on this article: https://support.chaos.com/hc/en-us/a...%20properties., Corona enables us to obtain more realistic lighting and shadows than V-ray, which is obvious by practical trials. Then, what are the modifications that boost V-ray results up to the level of Corona results, away from any editing the render's results in the post-production stage?

best wishes.

Well to be fair they never stated "Corona enables us to obtain more realistic lighting and shadows than V-ray", they said that out of the box it's easier to achieve. Although it's indeed somewhat weirdly phrased. For the last 5 years I haven't touched almost any options in VRay to achieve photoreal results. As long as your lighting, camera and materials are set up properly there shouldn't be any thing besides this to achieve realism. And I wouldn't do anything different in Corona to achieve more or less the same, although it's been a while since I used it.

There are some threads here on the forum discussing this although I don't think anything came out of it. It's more the colormapping side of things in Corona that is different and produces somewhat punchier results, here's one: vray and corona - Chaos Forums

[piotrus3333]

heh..
start with limiting GI to 25 secondary bounces and matching Corona's aa filter. this is the base of Corona look.

[vladimir_krastev]

Hi majid_shatnawi and thanks for posting. As others already mentioned V-Ray's UI has more options available to the user that affect the rendering result compared to Corona. In unexperienced hands this may lead to poor or at least not the best possible results. If you keep your render settings to default both render engines are capable of producing high quality images combined with excellent performance.

[suzanne_doherty]

I'm not a Corona user, but I did have to jump on it a few times in my last job.

For me, I get very "Corona looking" renders by using the filmic tone mapping in the VFB, generally using Hable, with a White point of 1. Then lighting to suit this tone mapping.

I believe Corona use Filmic tone mapping by default, so you immediately get that "film" look.

[piotrus3333]

I'm not a Corona user, but I did have to jump on it a few times in my last job.

For me, I get very "Corona looking" renders by using the filmic tone mapping in the VFB, generally using Hable, with a White point of 1. Then lighting to suit this tone mapping.

I believe Corona use Filmic tone mapping by default, so you immediately get that "film" look.

AMPAS should be the closest tone mapper to ACESOT from Corona as both try to emulate the same thing.

But white point of 1 in Hable does not sound right. most “filmic” display transforms are within 10-17 range. ACESOT is a bit above 16.

[suzanne_doherty]

AMPAS should be the closest tone mapper to ACESOT from Corona as both try to emulate the same thing.

But white point of 1 in Hable does not sound right. most “filmic” display transforms are within 10-17 range. ACESOT is a bit above 16.

I think that's probably just down to my personal preference, rather than trying to emulate the look exactly.

I also keep my white point at 1, as my style is to not bring the highlights down, I'd rather control these with the intensity of the lights. If I use a higher white point, I'll lose contrast, and have to compensate back again with over bright lights. But that's just me

[piotrus3333]

I think that's probably just down to my personal preference, rather than trying to emulate the look exactly.

I also keep my white point at 1, as my style is to not bring the highlights down, I'd rather control these with the intensity of the lights. If I use a higher white point, I'll lose contrast, and have to compensate back again with over bright lights. But that's just me

peculiar indeed.
but as always: whatever works.

[sirio76]

@majid_shatnawi

From my test (specific on this topic) I would say that Corona uses Hejl-Dawson filmic tone mapping. I’ve done the tests a couple years ago when they didn’t have ACES and probably something is changed since then.
Other than this I confirm you need to slightly change the GI secondary bounce, tune a bit the LC retrace parameter and the AA.

With this you will get mostly the same look if you are using basic flat materials, but then there are real production materials, and this will add a lot of complexity if you need to get the same look.
It seems that Corona cuts away part of the “energy” from the shaders and tends to avoid by default over saturated/bright/reflective materials, this may help unexperienced user but is a big limitation IMO, again I’ve done my tests before the introduction of more recent shader system so maybe something is changed.

All that being said, you don’t necessarily need to match 100% Corona output and to get a nice easy photographic look here is my base recipe, starting from linear tone mapping add an exposure layer with highlight compression set to 0.2, add a LUT (I use Kim Amland photographic LUT normalized linear) set in linear mode, you can also tune down the blending a bit to 0.8 opacity. Then of course you can perform other tuning like white balance, etc.
You can check exterior and interior renders on my profile media tab, if they are good enough for you they are all made starting from this base.

Naturally Vray offers far more advanced options, but probably you are just looking for a good/easy solution.

[majid_shatnawi]

First of all, thank you all for your response.

In the article, he did not say that directly. As Vizioen said, but in the article he referred to this indirectly.

In general, Corona shows a better result with little editing in frame buffer, but in Vray, I'm trying playing with Filmic Tonemap, ACEScg, and LUT files, etc. to get the same result. But my team is always able to distinguish whether this render is from Corona or Vray; I don't know why or how, but in Corona, there is something special, and a lot of designers can detect that.

I generally prefer Vray over Corona because, they both produce realistic results, and Vray, in my opinion, is more efficient in practice. But there is a special aesthetic feature in the Corona results that I have not yet been able to emulate in Vray, despite many experiments.

I will repeat some experiments based on the information you provided me, and I will come back to share them with you.

Thank you again for your response ❤. I hope you understood me, and I apologize if there is any weakness in my language.

[hill_lam]

First of all, thank you all for your response.

In the article, he did not say that directly. As Vizioen said, but in the article he referred to this indirectly.

In general, Corona shows a better result with little editing in frame buffer, but in Vray, I'm trying playing with Filmic Tonemap, ACEScg, and LUT files, etc. to get the same result. But my team is always able to distinguish whether this render is from Corona or Vray; I don't know why or how, but in Corona, there is something special, and a lot of designers can detect that.

I generally prefer Vray over Corona because, they both produce realistic results, and Vray, in my opinion, is more efficient in practice. But there is a special aesthetic feature in the Corona results that I have not yet been able to emulate in Vray, despite many experiments.

I will repeat some experiments based on the information you provided me, and I will come back to share them with you.

Thank you again for your response ❤. I hope you understood me, and I apologize if there is any weakness in my language.

This is really a very interesting topic! I can also tell at a glance which images were rendered with Corona and which were rendered with VRay.

I have always doubted whether Corona's rendering quality is really better than VRay. Because my colleagues and net friends always keep telling me so.

I tested more than 20 scenes in the past 3 years - some of my own and others provided to me by those who believed that Corona was better.

I can easily achieve 99.9% of the results with VRay every time. Here is an example: Corona vs VRay GPU - Chaos Forums

Recently, I even compared the quality of Vantage to Corona - almost the same. Here is another example: Vantage vs Corona - Chaos Forums

But it’s hard to explain why many people can tell the difference between Corona and VRay at a glance, right? This is truly a mystery of the century. I suspect that people who learn Corona imitate the colour grading style of a few early famous Corona instructors or scenes. Then these people become instructors and influence more people. Gradually, Corona's style became unique.

I also found that when VRay's display correction is set to Gamma 2.2 and tone mapping is set to AMPAS, I get exactly the same results as Corona ACES OT and exposure +1.0. This means that VRay's AMPAS is exactly the same as Corona's ACES OT.

[marcin-corona]

Hi all, it's Marcin (Maru) from the Corona team here. Better late than never, at least I hope so...

First and foremost: obviously both Corona and V-Ray produce realistic lighting and shadows (and everything else!) out of the box. If you would need to adjust the defaults each time you start working with an empty scene, I am sure 99% of users would immediately jump to the other engine.
The sentence quoted in the original message here was definitely confusing and it is now removed from the article.

As to comparing V-Ray and Corona, I believe one important thing to consider is that Corona has always been focused specifically on architectural visualization while V-Ray is for... everything. Because of that, it is possible that when working on archviz scenes, many users (especially beginner users) will find Corona more intuitive. If you use Corona in other areas, let's say character design or VFX, you may need to use some complicated workarounds and things may generally not be working as you would want them to. This is where V-Ray comes in with its "you can achieve anything you want" toolset.

I will refrain from using the ancient art of car comparisons, so let's put it this way: both render engines are like top quality multitools (you know, that kind of Swiss Army Knife thing that you can carry in your pocket). Corona has a lower number of tools and they are intended mainly for specific tasks - let's say, repairing electronics. V-Ray is a much larger multitool with lots of different utilities that you can use for pretty much any job you can imagine, including - but not limited to - repairing electronics. People who professionally repair electronics will most likely pick Corona, because usually they only need a specific range of tools. But ideally, it is best to try both multitools and pick the one which you find easy to grip and which gets the job done efficiently.

On this topic, I highly recommend checking out this episode of CG Garage where Chris Nichols talks with Corona Product Manager Tom Grimes about the differences between Corona and V-Ray, and more: https://www.youtube.com/watch?v=h3llDHSWOI8