Author Topic: Corona tests  (Read 52524 times)

2013-11-27, 09:42:59


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These days, it seems everything Peter Guthrie tells me to do, I do. I'm going to have to watch this before it gets me into trouble (on the other hand, Peter is definitely not the worst person to get directions from).

So, after he mentioned playing with Corona, it was only a matter of time before I had a go at it. But to be fair, I had been watching the forum for some time and was very intrigued by the great images by Juraj, Blackhaus and others. (Credits, too, to Peter and Lasse at Xoio for waxing lyrical about Corona over a recent lunch).

Here are a couple of images I put together using mainly old assets re-shaded from scratch (trying to understand how things work in the process). I had some minimalist post-pro done to them: curves, CA, glow and a photo filter in some cases. But nothing too drastic.

I also thought I'd jot down a few comments about the engine. Please bear in mind that I've only scratched the surface. In particular, these were rendered using PT/PT and leaving pretty much all the settings at default, with one exception, which was lowering the highlight compression from 1 to 0.5 (not sure what it does but it looked nicer). So it can be that my comments are factually wrong. If so, I'd appreciate it if the more experienced users could point out my mistakes.

- Simplicity: The fact that great results can be had right out of the box is amazing. Whatever you do, don't make it more complicated.
- Speed: Corona is blazing fast on my Z820. Half of these images were rendered small at 1200x1200, the other ones at 2400x2400. I left most of them to render for a few hours but, really, the small ones were very usable after 30 minutes (comparable to Octane on one solid GPU). And these scenes are not simple HDR-lit product shots. They are all taken in a physically enclosed space, with lots of indirect lighting bouncing around. Some of the images are slightly noisier, but these are the ones I stopped after an hour. Given a bit more time, I'm sure they would have resolved completely, including the (very nice) bokehs and highlights.
- Light: I can't quite put my finger on it but I find the way light diffuses very subtle and pleasing.
- Great material preview with quality setting: Definitely a workflow improvement over most other engines.
- Beautiful glass and metal: Again, I'm not sure why that is, but I find convincing glass and metal are much easier to achieve than in other engines I use regularly. They also render a great deal faster.
- I love the fact that one can open, close and resize Max windows while rendering. A small point but it makes life nicer.

- A physical camera: These were all shot through the V-Ray Physical cam, just because it's the one I tend to use all the time. I have no patience for the standard Max cam and its fantasy Mickey Mouse settings. Of course, none of the Physical cam's settings work, but I think the possibility to tweak F-Stops, shutter speed, ISO, etc. in the camera would be a cosmic improvement on the current workflow, which involves (at least as far as I can see) changing the intensity of the lights one by one to get the desired effect. Perhaps this is because I like to work like a photographer but this way of doing things is quite painful, I think. Let me know if I'm missing something here.
- DOF: I couldn't find a way of tweaking the depth of field in the camera. Corona seems to apply a "standard" DOF that has nothing to do with the F-Stop. I know there is an override in the render settings but touching those seems like a very inefficient way to work. Now there may be some settings for this in the standard Max cam but I couldn't find them.
- SSS: I couldn't find it, so assume there is no SSS material, although I haven't played too much with the translucency and absorption settings (not sure what the latter does, really). I render quite a lot of food, but things like Marble, candles, tree leaves will also never really work without SSS.
- I missed my favourite plugins a lot (Multitextures, MightyTiles, Railclone...) Getting these supported would make a huge difference for me and may actually be the thing that would tip the balance towards full-time Corona use. Conversely, it would be hard for me to use Corona as my primary engine without such support. Similarly, V-RayDirt and V-RayDistance are also things I use literally all the time, especially in big scenes where I don't want to unwrap all the geometry. Working without them would be a step backwards.
- Itoo's ForestPro and Railclone have a very memory-efficient way of distributing instances in Vray and Mental Ray, which, as per Itoo's website, is not available for other supported renderers, meaning no scene in these renders can every be as complex. For someone like me, who tends to work on big, not very optimised, scenes that fill all of my 32GB, this is definitely an advantage. I must admit I haven't tried Corona's scattering tools. 
- A Blend material allowing the merging of more than two materials. I do think the Max Blend mat works wonders for Corona. It looks really, really good. But merging blends with blends if one needs more than two layers seems like an inefficient way of doing things.
- HDR sampling. I'm not sure I'm getting the same quality of shadow definition from big HDRs, which I get from V-Ray or Maxwell. Again, it's perhaps a bit of a subjective thing and maybe there's a setting I overlooked there.
- I love progressive rendering but in rare cases, it is actually nice to have buckets, for instance to check the final image output on a very small portion of the image. (Couldn't find how to do a region render in the Corona VFB but must admit I didn't look very hard).

If this sounds overly critical, then it conveys the wrong impression. I was generally extremely impressed and, with some of the above-mentioned issues fixed, could consider a full switch to Corona.

Having said all this, here are the images:

« Last Edit: 2013-11-27, 10:02:54 by BBB3viz »

2013-11-27, 09:52:32
Reply #1


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2013-11-27, 10:05:15
Reply #2


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Сool pictures

(Multitextures, MightyTiles, Railclone...
Corona - "young" render engine,  so it may be available, the question of time.
Instead Multitextures  you can use Material By Element + Multi/Sub Object.
Corona have "Corona AO"
Corona support ForestPro and Multiscatter in last builds

« Last Edit: 2013-11-27, 10:15:45 by SHD »

2013-11-27, 10:10:51
Reply #3


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Hi Bertrand,

Not sure if you have the latest build, but there is a camera modifier that has physical cam settings.

There is an AO map that you can use to create dirt, its not as fully featured as vray's but its pretty good, inverted normals etc..

Forest pro and multi scatter are already supported.

HDRI sampling theres options in the dev build that gives you precision over sampling v's speed.

There is a bucket mode too.

Just us the Render region in 3dsmax VFB or Viewport and corona will render the same thing, its not as nice but its there.

I'm sure Keymaster will give you access to daily builds.

I started using Corona couple of years ago and through out Mental and Vray back then :)

Anyway its great to see you pros showing interest in Corona.


2013-11-27, 10:25:25
Reply #4

Ludvik Koutny

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Hi and welcome! :)

Images are really great, and i am surprised their quality is really on par with your vray renderings, considering that Corona does not have SSS yet and layered mat. support is only very basic :)

As for your questions/suggestions, here are some answers:

- You can get some significant rendertime boost at the small expense of accuracy by simply switching secondary GI to HDcache...  that is all...  you can leave it at defaults (eventually, you may want to decrease precomp. density parameter to 0.1 for very quick rapid previews, and return it to 1.0 for your final renderings)

- Some of the Physical camera settings such as F/stop, ISO and Shutter speed are implemented in daily builds which you can get access to, and these features will make it to next public release as well :) Those settings of course work together and impact each other like real physical camera does.

If you want access to daily build, you can either PM me or Keymaster ;)

- In post processing tab, there is an exposure compensation value which works like simple exposure adjustment as seen in cheap digital cameras and cell phones. So that allows you to adjust overall scene exposure without having to change intensity of actual lights. This was done as a temporary measure to give users some control over exposure before actual physical camera get's implemented (Which it already got, as stated above :) )

- In alpha V5, lowering highlight compression is a correct way to increase contrast of your images. Some people were actually using gamma for that instead, which was wrong. In daily builds and next alpha release, there will actually be also contrast function in post processing settings, dedicated for this case :)

- In alpha V5, DoF is actually based on an F/stop parameter. So setting F/stop to 2 for example should create identical DoF amount to one you would see in Vray with similar parameters. It is located in render settings - Depth of field/Motion blur rollout, right under the enable DoF checkbox. Focus distance is then defined by target distance of Max's camera, or can be manually overridden using focal depth parameter once you un-check "Use target distance".
In daily builds and next alpha release, these settings are located in camera, but they can be globally overridden by settings in render settings dialog if one wants to.

- SSS is indeed not yet implemented, but could possibly make it to alpha V6. No skin shader probably, but at least some basic function to simulate fruits, wax, marble, etc...

- We already support ForestPack Pro from iToo. I suppose we could contact them to resolve support for other their plugins.

- Equivalent of VrayDirt in Corona is CoronaAO, as for distance map, it is planned and it will probably make it to Alpha V6 :)

- As for instancing optimization, i think Corona can  handle some reasonable amounts of instanced geometry, you can look for example here:;topic=630.0;attach=2342;image,1997.0.html,1873.0.html,1168.0.html,1792.0.html,1482.0.html,1056.0.html,1001.0.html
And there is a lot more... :)

- Corona does not even support nested blended materials i believe. Support of Max's blend material is there to give users some basic blending support, but we plan more advanced corona-optimized blend material soon ;)

- From my experience, HDRI results from Corona were identical to vray. But Vray has VrayHDRI which talks directly to HDRI, while Max's native bitmap has some traps that needs to be avoided. Sometimes it can open image with wrong gamma, so you may need to override input gamma in bitmap browser window for some maps, and you also need to make sure you open your HDRs as 32Bit with def. exposure enabled ;)

- As for region rendering, it is currently not present in CoronaVFB, but still possible. In common tab of render settings window, there is an Area to Render frame, in which you set drop-down box to region. Then you adjust region in viewport. I got also a Ctrl+R shortcut mapped to "Edit render region" command so i can set up and modify my region rapidly. Once you adjust region, just be sure to hit [X] mark on the top right of the region gizmo, otherwise Max's UI remains frozen as it is still in region edition mode ;)

- Last, and very important things... if you ever do glass in windows, or some large areas where like glass railings or bricks, then set refraction mode in CoronaMTL to hybrid, this will create glass that casts transparent shadows instead of caustics. If you then apply such glass to for example window glass planes, you will get glass in windows with nearly unnoticeable rendertime difference :)

EDIT: Forgot to mention that things such as tree leaves, or sheets of paper will work well even without SSS. That's what Translucency in CoronaMTL is for. It simulates diffuse translucent scattering of very thin objects, such as paper, tree/flower leaves, curtains, etc... You should give it a try ;) You can either instance your diffuse texture into translucency color slot, or use different texture for translucency.
« Last Edit: 2013-11-27, 12:34:27 by Rawalanche »

2013-11-27, 10:29:23
Reply #5


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Amazing works with Corona Bertrand; did you use without problem the VRay converter (i think your scenes were made with Chaos engine no ?).
For all my complicated scenes I don't need all the things witch miss you, but I don't have your high level of skill. For example, I think it's very free to work without any VRay Physical Cam; with the real-time post prod settings you can correct and adjust a lot of things; maybe having the vertical correction could be nice...
Anyway there are a lot of things to add, but Corona is very accessible like that for simple artists like me, so it it the way developers will take i don't know. This engine is called to a great future in any case.

2013-11-27, 11:10:57
Reply #6


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ok, rawalanche answered most of the question, I'll just add some corrections:

- exposure compensation is not a temporary parameter, it will stay there indefinitely. You can use either it or the real physical cameras parameters, depending on what you prefer in your workflow.
- A6 wont have SSS, it is planned on sometimes at the beginning of new year
- use hybrid glass if your glass in windows is modelled as real glass sheets with thickness. If you have only single polygon in windows, use twosided glass instead
- you dont have to apologise for your constructive critisism/ideas. We are trying to eliminate the hugbox mentality (i.e. no criticism allowed, ever) here on the forum, which is sadly common in almost all 3DCG communities, but it sometimes leads to misunderstandings and drama.
Rendering is magic.How to get minidumps for crashed/frozen 3ds Max | Sorry for short replies, brief responses = more time to develop Corona ;)

2013-11-27, 11:31:26
Reply #7


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sometimes, I think that there is only -so much- talent in the world, and this mother***** has it all...

:(rage quitting smiley face):

2013-11-27, 11:37:46
Reply #8


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Bertrand is in the place !! Yeah !
Ouaw , Corona must be proud to combine now some of the best 3d artists of the world like Bertrand, Peter, Lasse, Juraj and others.
Like i said Corona will be a must have for all of us in the future or maybe a great tool added to others renders to boost the workflow.

For the images above , stunning as always,
It's almost disconcerting how you feel at ease with all engines, for the pleasure of all of us !
I'm still thinking that you can do impressive render with all the soft , maybe even with paint !! :)


2013-11-27, 11:39:14
Reply #9


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Welcome here BB

   Back in a day, i remember your mindblowing renders on Indigo forums (2006/2007). Then you moved to Vray. Now im glad to see you here now and i hope, that you`ll stay here with us when Corona will reach your requirements.

And images are beautiful. Im sure, that you want to try daily builds, where you can find more advanced features and support for MS/FP.

Most amazing thing is that you have used stock settings and not raised MSI to 400 (300/200) to achieve outstanding quality. This is reason, which is making corona different from other renderers. Simplicty. You even dont have a chance to ovethink / overdo settings with this small piece of software.

I think those images are great motivation for dev(s).
« Last Edit: 2013-11-27, 11:57:18 by michaltimko »

Supporting Corona in commercial projects since pre-alpha

2013-11-27, 12:16:57
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Oh!! Nice Work.

2013-11-27, 12:40:21
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wonderful!!!!!! BBBviz 3 you're always the best, with any program, you are a true render-man!!!!!!!!!!!!!!!!

2013-11-27, 12:49:36
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Bertrand up in this forum!

*rage quits*

But seriously, ridiculously realistic images as always.

Vray who?

2013-11-27, 13:06:14
Reply #13


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This is the day I was waitng for :) !!!! nothig to say, just perfect
Corona brought joy to sad world of 3Ds Max :)

2013-11-27, 13:21:30
Reply #14

Caue Rodrigues

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Looks great!!

Congratulations Bertrand!!

« Last Edit: 2013-11-27, 13:26:47 by crawlewis »