Strange renderings with VRay 1.5 R2

[baumgore]

Hi everybody.

We have here a lot of prints to render (over 200 in 30x30 cm 300 dpi), with MAX8 and VRay Adv 1.47.03 we got this:



with VRay 1.5 R2 we get this:



here are the main differences:



There are major changes in the way VRay 1.5 render soft reflections and GI. The scene is mostly lit by self illuminated objects to get very subtle metalic highlights, but even the only highlight made by an ordinary light has changed. It's the same file with only minor changes made to very few objects, but this isn't the cause for the render-changes.
Our main probles is than our customer is VERY, VERY, VERY keen about keeping standards, the old look has been validated and corrected for weeks. They want to print about 20000 catalogues in a few days, and need the new pictures beeing in EXACTLY the same mood as the old ones.
We will switch back to 1.47.03 and rerender if nothing else helps, but I want to know how these dramatic changes could happen.

VLADO please help !!!!!!!!!!!!

for everybody, this isn't the final look of the images, there are heavy duty post-processing painting/mood pases, the finals looks like this:

[Adam H. Stewart]

Go back to 1.47.03

If I where you I would go back to 1.47.03 right away and don't bother to try to make 1.5 act like 1.47.03 Check out my thread :

http://www.chaosgroup.com/forum/phpB...ic.php?t=17121

The official response I got from Vlado was - if you want something to look like 1.47.03 then you are better off rendering in 1.47.03 - I can't say I am thrilled with that prospect, but if I where you I would just reinstall 1.47.03 and save yourself the hassle of tweaking you're settings( that's what I just did for a project) to death.

There have been many changes in this release to both the reflection and refraction materials - even though the manual does not mention them. Apart from the mentioned AA changes. In my tests I found that 1.5 has problems dealing with the falloff and smoke procedural maps - compared to 1.47.03 that is ( it might have problems with other procedurals aswell ).
I do not know what lights you have in you're scene if they are Vray lights you could try toggling the Affect specular and Affect diffuse settings also check your color mapping settings do a test with sub-pixel mapping and clamp output on and then off - not sure which will work best.

Reading between the lines from other users I think there have been some key fundamental changes in Vray that could mean you will never be able to replicate the look of certain materials in the new version.

Hope this helps.

[vlado]

Yep, what Adam said.

As for the mentioned problems with procedurals, I have not been able to find any, so Adam, if you have an example scene you can send it over to vlado@chaosgroup.com for inspection.

Best regards,
Vlado

[baumgore]

I've tried everything, nothing helps. The bright reflection line at the horizont is simply wrong, there is nothing which could logically generate it, no reflection map, no reflection cube or light or something else. It is the cube which is generating the bright reflection in front plus a second cube out of the view on the right which generates the bright shading on the cutted surfaces. They miracousilly generate a second reflection on the ground. It could be VRay 1.5 R2 renders reflection another way, but this is definetelly a BUG. There is no 2 reflections of the same object on a perfect plane, plus the strage reflection is moved to the side and not in sightline to the cube.

Vlado I could send you the scene if you want to check it out.

[Da_elf]

im definately interested in hearing the outcome of this. i take it you have already tried to use your ray bias to 0.001 to fix that messed up little white piece at the top?

just out of curiosity, whats your ground plane made from. have you tried a vray plane?

[vlado]

I've tried everything, nothing helps. The bright reflection line at the horizont is simply wrong, there is nothing which could logically generate it, no reflection map, no reflection cube or light or something else.

Because of other problems, this part of VRayMtl (reflections at grazing angles) has changed - the surface will become diffuse in these cases. In general, this is an indeterminate situation for the phong/blinn BRDF models. In previous builds, for reflections at grazing angles you could get a rather random value - anything from a black line to the reflection color. Replacing a part of the grazing reflections with a diffuse color solves this ambiguity. This replacing effect is reduced as the surface becomes more mirror-like. In the real world, the surface would actually become more mirror-like at grazing angles (e.g. glossiness closer to 1.0) so there is no such an issue. If you use e.g. a falloff map for the reflection glossiness, you can get a similar result to the 1.4 version for this case.

With that said, we are working on more physically accurate BRDF models that do not have this problem.

Best regards,
Vlado

[Adam H. Stewart]

File sent

Hey vlado I just sent you the file from my post - the red tinfoil material.

http://www.chaosgroup.com/forum/phpB...ic.php?t=17121

It seemed from testing that it was the smoke procedural that was causing weird noise on the right side of the object. I have another scene I will dig out that was creating similar problems with the falloff material. Once I turned the procedural off 1.5RC2 rendered identical to 1.47.03 - hence my conclusion it is not an antialias or ray bias thing - although I could be completely wrong.

[Da_elf]

looking forward to the new BRDF version

[baumgore]

Hi,

what about implementing back the old Blinn-code under the BRDF chooser ??? I am a first alpha-day VRay user and never had problems with it.
This would save my day, switching back to VRay 1.47 is interfering here with other jobs, and the customer will come back soon with the next millions of pictures.

VLADO is it possible to dig out your old Blinn-code and implement it in a modified R3 version (MAX?????? PLEASEEEEEEEEEE !!!!

[vlado]

VLADO is it possible to dig out your old Blinn-code and implement it in a modified R3 version (MAX?????? PLEASEEEEEEEEEE !!!!

No, but you can run both versions in parallel if you copy the 3dsmax 8 folder and install the 1.47 version into the copied one.

Best regards,
Vlado