vray 3.6 adaptive lights odd clamping

[anthonyh]

hi,
it *looks* like the sub-pixel/clamp output might not be working the same in 3.6 with adaptive lights ? (check the white line at the top of the image and highlights at bottom) same in IM and BF.
one thing i noticed as i had an IM/LC solution saved from vray 3.4, vray 3.6 doesn`t seem to like using it, rendered much noisier and slower, regenerating it solved it though. put this down to engine changes ?

cheers
anthonyh

[Alex_M]

I am reading the changelog file at the moment and maybe this is related to your issue:

Modified features:
(*) V-Ray: Disable subpixel color mapping when using adaptive lights;

So looks like subpixel color mapping now gets automatically disabled when we use Adaptive lights? Maybe Chaos will confirm.

You can find the changelog file usually in C:\Program Files\Chaos Group\V-Ray\3dsmax 2016 for x64\docs. I always read it after I install a new version of Vray, it's helpful to know what is changed and updated.

[vlado]

So looks like subpixel color mapping now gets automatically disabled when we use Adaptive lights? Maybe Chaos will confirm.

Yes. V-Ray prints information about this in the message log.

There are a few alternative ways to reduce jagged edges on very bright objects, f.e. lens bloom and/or using a larger AA filter. We will probably remove the subpixel mapping option completely in the future as it prevents us from doing other sampling optimizations.

Best regards,
Vlado

[anthonyh]

hi Alex_M,
strange, i wonder why that is. that would mean it`s now manually uncontrollable ? i don`t think i like that. i get files from clients regularly and i need them to be able to render *as-is*, not having to spend my time relighting their scenes. that costs me money and is not an option i`m willing to consider.
re: i didn`t know that, i was looking for the changelog online but couldn`t find one. good to know it`s local too.
thanks
anthonyh

[vlado]

strange, i wonder why that is. that would mean it`s now manually uncontrollable ? i don`t think i like that. i get files from clients regularly and i need them to be able to render *as-is*, not having to spend my time relighting their scenes. that costs me money and is not an option i`m willing to consider.

We didn't really have any choice in this matter. The subpixel mapping option is a (biased) cheat and it produced artifacts when used together with the adaptive lights. The two cannot be made to work together.

Best regards,
Vlado

[anthonyh]

vlado i kinda hope not. as i said, files i get can be made using legacy versions and that`s going to require fiddling which costs me time. lens bloom is out because i do grading/FX in AE. wouldn`t a larger AA filter slow the rendering ?
i suppose the workaround is not to use adaptive lights then.
cheers
anthonyh

[vlado]

vlado i kinda hope not. as i said, files i get can be made using legacy versions and that`s going to require fiddling which costs me time.

The only way to make sure a file renders 100% in the same way is to use the same version that it was saved with. In recent builds, you can use the MaxScript function vraySavedVersion() to find out what that version is.

lens bloom is out because i do grading/FX in AE.

That would still take care of the problem just fine, so long as you work with the HDR information.

wouldn`t a larger AA filter slow the rendering ?

It depends on the filter size, but probably not by much.

Best regards,
Vlado

[anthonyh]

hehe, i tried doubling the AA filter. ewww, it looks like my eyes are covered in soup. welcome to blur town.
anthonyh

[Alex_M]

Try the Soften anti-aliasing filter with a size of 4.0 if your render resolution is about 12 Mpix. You may need less than 4.0 if resolution is smaller. I remember solving some similar aliasing issues with it in the past and it didn't blur the texture details much.

[anthonyh]

hi Alex_M
thanks i`ll give that a go. it seems lowering the burn value helps a little at the cost of overrall scene brightness but i can probably fix that in post.
anthonyh

[Crayox13]

I'm a freak for details, especially when I have fabrics like carpets or complex couch fabrics that need detail look to show those tiny details like in velvety materials. I always used subpixel mapping with AA turned off and thought that was the way to go for full detail with no blurring. Didn't know subpixel is a "biased cheat" as Vlado puts it. So what do you recommend instead? For those who don't want "blurry" renders?

[anthonyh]

i tried a bunch of workarounds, best i could do was a vrayoverride material for illuminated sources, duping the material to be able to tone it down manually and also turning the burn value down a bit for general burn. also i wish the burn value only affected top end values first before affecting the rest of the scene but it seems to affect overall scene brightness at the same time too(not sure i explained that right).
as for the sub-pixel being a `cheat`, isn`t adaptive lights kind of a cheat too ? i mean if you don`t evaluate all lights in a scene then it`s not strictly a 100% physically correct render. it might not make much of a difference visually but still.
anthonyh

[kosso_olli]

I always used subpixel mapping with AA turned off and thought that was the way to go for full detail with no blurring.

Using no AA filter doesn't make any sense in my eyes. I don't know where, but somewhere Vlado stated that you put unnecessary stress to the image sampler, because the noise is much more pronounced. I always think of V-Ray as my virtual camera, and I have yet to see a real camera that takes pictures as sharp as V-Ray renders. Often I use the soften or cubic filter as Alex_M mentioned, because that way I am much closer to the photos I am integrating my renders into. Even the very expensive cameras like Alpa or Hasselblad with their high res digital back are quite soft.
Attached you can find a 100% crop of the sharpest point of an image taken with a Phase One IQ1 100mp back with a Schneider Kreuznach lens. Pretty high quality stuff, but still, the edges have a soft blur.

[Syclone1]

This thread has me thinking (that's where all the smoke is coming from lol) and in the real world if you have those glowy effects in a photograph that I believe is the result of poor or dirty optics in your lens and then on the other spectrum I know as a photographer myself and seen others use fine materials like nylons or even a bit of petroleum jelly on or in front of a lens to achieve the nice glow around the highlights. I haven't tried it but wonder if the physical camera might behave in the same way if you put something like that close to and in front of the camera?