Hey guys,
I found an issue in handling the clearcoat of VrScans materials: In V-Ray 5, the clearcoat seems to have a glossiness value below 1, as the reflections are blurred. In Next though, the reflections are razor-sharp. I do wonder where the difference is coming from. I mean, the VrScans are measured, so why can there be such a deviation in the output?
I can not find anything about this in the changelog, nor in the documentation.
So I really really hope this is a bug, and not a feature…
I haven’t managed to recreate the difference with the clearcoat in a simple scene. Could you send the scene to tanya.todorova@chaosgroup.com for investigation?
Thank you for the report and the provided files. There seems to be a difference, indeed. I have logged the issue (internal bug-tracker id: VMAX-10122) for developer analysis.
After developer analysis, it has been concluded that this is the current expected result. Before V-Ray 5, clear coat specular highlights were considered negligible, because the clear coat was added on a pre-measured IOR value - hence the CC properties were not fully recreated. Currently, however, we’ve improved the ability to scan highly reflective materials which rely on the clear coat rendering. We can directly compare the rendering result with the images in the raw scan, and the goal is to have as much similarity as possible.
To be fair, carpaint can be surprisingly shit in terms of blur and orange peel, but clients often don’t want that in the paint. If there was a way to override that and have an option for totally clean and crisp coat, then that’d be useful. Cant the coat be disabled in the scan and then added back on in a blend material?
It sure can, as additive.
Just watch out for reflection values, keep them lower so to leave room for the underlying VRScan, rather than breaking through the EP ceiling.
So if you use a blend shader for this, with the scan at the base, and a vray material set to be full mirror in slot one, and a fresnel in the mask control, would that not work fine? Rather than using additive? Thats basically how I setup my non vr scan car paints. I assumed additive was the devil in blend shaders, when realism is the goal, and should be avoided at all costs. This way you can then dial in a fraction of blur in the gloss and use a custom orange peel map, and not worry about energy conservation.
You can most definitely set up the shader as you please.
Me, i’d rely on the microfacet fresnel of the vrayMtl, rather than the poor fresnel of a texture, and work in a way which will allow full recomping latitude (which blend may not allow, depending on setup.).
If i have to pay for the price of figuring out my coat values.
Also, i *deeply* dislike full-on values in any shader, since time immemorial: masking with a fresnel makes no difference at grazing angles, and then fireflies appear.
Cue people cutting energy values and clamping, when in fact it was always a case of a not well thought out shader set up.
Thankfully, that’s none of my business anymore, so no one has to suffer my setups.
Sorry, this explanation does not make any sense to me. I used a carpaint which was digitized a few years ago, without the “improved” clearcoat. So I expect it to render the same in Next and 5.
Also, I can not sell a blurred clear coat to my clients. Reflections in clear coat just do not look this way. In the examples of the first post, the reflections are just a blurred mess.
Well, you can disable the orange peel by setting the bump amount to 0. But you can not control the blurriness. Clearcoat is not blurry, I do not know why it looks that bad in 5. I strongly consider this as a bug, not a feature. One thing more on our list of why to avoid 5 so far.
Hi Oliver,
the old scans were set to very high glossines,and even with the changes the should remain sharp enough.
If you have already sent a scene, i will investigate the material and why is thishappening, if not, you can just tell me the material name
Hi Ivaylo,
here is the answer from Aleksandar Hadzhiev: “Thank you for the report and the provided files. There seems to be a difference, indeed. I have logged the issue (internal bug-tracker id: VMAX-10122) for developer analysis.”
If you need anything else, please don’t hesitate to ask.
Well, i tested it with the simplified stene provided, and wasable to reproduce it. Just for information, the blur is bigger than the expected one because the camera is parallel.
Here are the suggested sollutions, starting with the fastest one
1. The problematic material canbe modified to produce the same result as in vray next (already tested this, it works), i can send it to you immediately
2. A command line tool to introduce this correction in any material, can be prepared approximately until the end of the day
3. The materials scanned before the glossines change can be rendered in the old way, you have to wait until the first service pack
Ivaylo, thanks for checking. Solution number 3 is fine for us, because we postponed the update to 5 anyway. Right now there are too many issues that need to be adressed, this was one of them.
