Vray Next vs Corona 4

[dfcorona]

Wanted to get you guys opinions on Vray Next since most of you came from Vray or still use it but also use Corona.  We own Vray 3x version and Corona among other renderers.  We are going to keep using Corona but might use Vray Next for animations. Had some observations and questions.

We just used Corona 4 nightly for an animation, render quality, user interface & user friendliness is fantastic. Render times get to be quite large compared to Vray Next that we tried for a few small tests, and that can really add up for animation.  Vray Next IPR seems much more responsive and final rendering seems to be much faster.  But my question is about quality, many Corona renders look very realistic compared to Vray.  Not sure if this changed with Vray Next, but I can't place my finger on if it's Coronas lighting or shaders.  Seems to have more depth and reflective properties seem more natural. Like I said we had only limited time with Vray Next trial, so for those who use both would love to hear your opinions or even see you comparisons.

[danio1011]

We just ran through a scene with Next to see how some new GPUs performed.  It did render verrrrry fast and in my opinion the viewport didn't lag nearly as much during IR with Forest Pack.  For us Corona has really gotten slow with FP distributions during IR.

That's the good news.  Bad news was we found the reflection\refraction in glass to lack a certain 'depth' and realism.  Multiple people commented on it and we just couldn't get it where we wanted.  Hard to put your finger on but it just didn't seem right.  Corona always gets glass 'right.'  Also the denoiser leaves something to be desired.  If you have fireflies it creates these huge white squares.  I understand this is going to be fixed soon.  And if you're using Next GPU the denoiser seems to really screw up glass as well.  It's a bummer, because since the denoiser has issues, even if you render for hundreds of passes to avoid having to denoise, there still will be some grain and it won't be even across the image so it doesn't look like film grain.  It'll be totally clean in one spot and then (usually behind glass) noisy as heck.  Perhaps this has to do with adaptive dome light sampling, it just seemed like we kept hitting walls when it came to final quality issues.  I was also disappointed to discover 2D Displacement isn't supported on the GPU, one of VRay's best features.

We think we might end up using Next GPU for certain types of animations.  We'll see.  FStorm is really nice too and, aside from lacking a denoiser, not supporting becrontiles, etc, is a pretty good GPU option for certain types of scenes.

Just our\my impressions.  Jumping back into Corona was kind of a relief.  Hope that's helpful and I'm sure others will chime in.  Cheers!
Daniel

[dfcorona]

That was great danio1011, thanks for your experience. This is what I'm kinda finding also. I am now putting together a scene with Vray Next and then will remake it in Corona. Vray Next GPU is very fast, which is nice but it also is so slow in development. Missing many features you can get with say Redshift.  IPR if it's Vray CPU or Gpu seems much snappier than Corona and I've noticed that issue too with Forest Pack. But the scene I'm putting together with Vray the render is just getting that plastic feeling. Before I rendered with materials I did both scenes in vray and Corona with override shader and the lighting between both where quite different, this is an exterior scene. I know what your saying about depth, Corona feels like the scenes have actual depth where Vray Next feels flat. I also would like to use Next GPU for certain types of animations but the quality just leaves me kinda disappointed so far.  I'm not done with my own internal testing but will see what comes of it. 

I've tried Fstorm while nice I always hit Vram issues, so it's only ever good for small scenes. Octane does better but is limited in shaders and ALWAYS crashes over all the years we've owned it we were never able to use it for production once except one still that had it crashing all the time also, We've owned from the beginning and own the latest versions also.  For GPU nothing really beats Redshift.  Would love to hear more from others.

[danio1011]

dfcorona - Are you using Redshift for arch viz scenes?  I've never tried it but maybe now I will.  Interesting you run out of VRam with Fstorm, I've found it to be super efficient in that regard.  I think it's getting NVlink soon, so that should help.

Cheers,
Daniel

[dfcorona]

Yes Redshift for Archviz, It's super fast and never had a issue with vram.  It is missing some key features though but that is being resolved a lot in version 3.0 that's coming soon. It can handle massive scenes.  I always run into vram issues with Fstorm, especially with exterior vegetation, and it has no OOC.  Nvlink will help but i still see it having Vram issues even then with very large scenes.

[kosso_olli]

I have to agree with the opinion of most users here. In Next the IPR is much more responsive, it's faster then ever.
What I can not understand are the comments about the palstic look. Attached are some renders straight out of the VFB, with applied LUT. No further post work whatsoever. Looks good in my opinion...

[dfcorona]

Thank you kosso_olli for your info and pictures.  I agree that Vray can render cars realistically.  But find some interiors or exteriors with different materials and vegetation.  They seem to always show a plasticy look from Vray to me, now that we are use to the realism of say Corona and Fstorm. There might be a handful of them that look so good I can't tell there Vray. Every time I see a render from Vray now I can tell it is Vray, it has a flat plastic feel. Characters and cars always seem to come out good.  I think one major issue with Vray is how it handles Vegetation also, It always seems to feel less quality than other renderers.  I had to take a break because of work but I want to get back to my testing between the two.

[kosso_olli]

Well, the old Alfa from the side has vegatation in it, the grass, wall and the hedge. Same for the Mazda: Racetrack, Grass, Hills etc. are all rendered.
The Dodge in the fog also, it is full CGI. Droplets the same. The only car on photo background is the BMW. So I think V-Ray can render any environment in a realistic way...
But here are some more I did with Forstpack and some assets from Megascans.

[dfcorona]

Those are hard to tell anything because Photo-scanned objects can look just as real in a game engine. I'm talking full scenes interior and exterior, the majority of them don't look as realistic as corona.  Like I said I cannot pin it down to Lighting, Shaders, or possibly tonemapping.  I know that I've heard a lot of people also complaining how vray handles Bump mapping, so maybe it is a shader issue.  But I have to say again it's IPR and render speed is pretty amazing.

[kosso_olli]

Erm, as I said, besides the BMW, all images are full cgi exteriors.

[danio1011]

Nice images!  I had good luck with vegetation, particularly megascans stuff.  And I was very, very pleased with the interactivity with Forest Pack and IPR.  For us the issue really was the glass, particularly indirectly lit glass.  Aside from the denoiser making a bit of a mess of it, even when not denoised the refraction\reflections in glass didn't seem to have the look and depth we'd expect from Corona or FStorm.  I showed a couple of colleagues the scene we were working on without mentioning we were using VRay and they both said, independently, something along the lines of 'Nice!  But the glass doesn't have a lot of depth...?'  A short time after that I noticed on the FStorm facebook page Grant W. commenting on how he was much more pleased with FStorm's refraction than VRay's.  He seems to like VRay a lot from what little I've seen of his recent stuff, so I thought that was significant and somewhat relevant to our independent experiences.  Not that his word is Gospel or anything, I just thought it was worth mentioning.

It's kind of an aside, but we also encountered 4+ serious bugs in one week (VRay Camera randomly loses vertical correction, Max had to be restarted.  Bucket rendering randomly skips half the rendering, had to switch to progressive.  Denoiser generates large white squares on fireflies.  Render regions occasionally not being respected, not serious but annoying.  Switching to material override generated an error, Max crashed.  Running out of VRam often makes Max crash.)  I reported most of these to CGroup and they were able to reproduce a couple of them so that's good!  I just never really see that level of bugginess with Corona or FStorm.  So while the renderings went faster and interactivity went up, production actually slowed due to some of these issues.

All that said, we're still considering using VRay Next on certain types of jobs.  I think there is potential there for us, this is just an unpolished representation of our experiences.  Heck...I spent a healthy chunk of change on a couple of 'test' GPUs, I would like to use them occasionally :)

[dfcorona]

Erm, as I said, besides the BMW, all images are full cgi exteriors.

I guess I'm looking at this from more of a Archviz point of view.  I understand that the motion blurred exterior of the mazda is cgi, but hard to tell anything form well all the blurring. The cream side car is only 3 elements in the exterior where the rest is a photo. They look good, but when you have all elements of a full cgi archviz project, things seems to start looking well CGI.  I think the best is to have the same archviz project rendered in both, I'm trying that now and hopefully be pleasantly surprised by Vray, but so far not exactly convinced.

[kosso_olli]

Regarding the glass issues: There recently are discussions to increase the default Max depth parameter, as well as the reflect on backside option for the VrayMtl. These two options are well known to long-time V-Ray users, but new guys have no clue what they are. Both are neccessary to get good looking glass in any renderer.
The bugs you mentioned are unknown to me. Never had the bucket mode skip half of the image, nor does it crash when assigning an Override Material. Guess some stuff is down to the user.
But I can tell you something else: In my 12 years of V-Ray, I have seen a lot of renderers come and go. I tried all the promising ones (yes, including Corona), but so far no competitor ever matched the speed and the set of supported features. There is literally nothing I could not do with V-Ray.

[dfcorona]

Yes vrays supported features are amazing. Wish they would develop faster with gpu though, development on that is so slow.

[danio1011]

Regarding the glass issues: There recently are discussions to increase the default Max depth parameter, as well as the reflect on backside option for the VrayMtl. These two options are well known to long-time V-Ray users, but new guys have no clue what they are. Both are neccessary to get good looking glass in any renderer.
The bugs you mentioned are unknown to me. Never had the bucket mode skip half of the image, nor does it crash when assigning an Override Material. Guess some stuff is down to the user.
But I can tell you something else: In my 12 years of V-Ray, I have seen a lot of renderers come and go. I tried all the promising ones (yes, including Corona), but so far no competitor ever matched the speed and the set of supported features. There is literally nothing I could not do with V-Ray.

Reflect on backside was on (I always toggle this to evaluate results with glass).  I usually think of max trace depth as needing to be bumped higher with more complex glass situations than doublepane archviz glass, but perhaps it's worth a try.  With refraction I think of this as relating to thicker or more complex geometry, particularly when you start to see exit color show up (is that still a thing?)  I would also imagine that Grant would be aware of those settings, too, when making his comments that so closely aligned with our impressions.  I've been using VRay since 2009 at this point, so I'm not totally unfamiliar with the engine.

As for the bugs, I think it's just idiosyncrasies of user patterns and machine configurations, which are innumerable.  The fact that two bugs (so far) have been reproduced by CG gives a bit of credence there, and I haven't seen that instability in other engines.  But again, it could be pure bad luck.  It also seems to be a known issue that in GPU the denoiser doesn't treat glass very well, so that is a bit of a downer for archviz.

I'm not saying VRay doesn't have features or potential, I'm just relaying our impressions.  It sounds like it's treating you well.  It certainly has lots of features and is fast!