Scattering Fog does not work with reflections or refraction

[rita_sobral]

Hello,
Something I have been trying to work around for some time is that scattering fog does not affect reflections or refraction even though those ae ticked in 3ds max envrionment settings.

It's starting to get to the point where I have to change a whole scene or camera angle just because of this issue. You basically make scattering fog unsuable in many cases if not all where there are any refracted material/glass or relections such as water for example.

The other issue with this is that you currently do not properly support opactiy maps meaning your current work around for semi transparent maps is to use refraction - which leads back to the original problem which is scattering fog does not support refractions causing another visual issue.

When you toggle affect seconidary rays in Vantage your whole colour space becomes distorted. Toggling scatter GI after pulls it back a bit but still the GI is distorted and scene is now completely different to when those toggles are off.

Thanks

[vladimir.nedev]

Something I have been trying to work around for some time is that scattering fog does not affect reflections or refraction even though those ae ticked in 3ds max envrionment settings.

It's starting to get to the point where I have to change a whole scene or camera angle just because of this issue. You basically make scattering fog unsuable in many cases if not all where there are any refracted material/glass or relections such as water for example.

Since Vantage doesn't have individual "affect reflections", "affect refractions, "affect GI", etc options for the fog, the value of "Affect secondary rays" is sourced from "affect GI" from the VRayEnvironmentFog.
Reflections and refractions should be affected by the fog in this case, aren't they ?

When you toggle affect seconidary rays in Vantage your whole colour space becomes distorted. Toggling scatter GI after pulls it back a bit but still the GI is distorted and scene is now completely different to when those toggles are off.

Can you send us an example scene for this ? Are you comparing the result to V-Ray ?

Greetings,
Vladimir Nedev

[rita_sobral]

Attached some comparison imags to help show this.Slight exposure differnces between vray and vantage but shouldnt matter. There is a glass material in all images which you can obviosuly see in the default vantage screenshot.


Affect GI in Vray is on by default from 3ds max, turning it OFF there is a shift in the GI causing colour differences

Affect Secondary Rays in Vantage - which is apparently linked to Affect GI, is off by default in Vantage and when you turn on there is a colour shift in the GI - very noticable on trees. But refractions and relfections now work.


Vantage 'Affect Secondary Rays' + Scatter GI' give similar results to Vray with 'Scatter GI' and 'Affect GI' but fog and GI are now different. Undesired.


Default Vray is how it should look, but it's impossible to get that in Vantage with Reflections and Refractions included. My final question is why are reflections and refractions not on by default in Vantage as they are in Vray?

Thanks


Default Vray settings below

General parameters
Scatter GI == false

Ray filter
Affect background == true
Affect reflections == true
Affect refractions == true
Affect shadows == true
Affect GI == true
Affect camera rays == true

[vladimir.nedev]

Can you attach the .max scene as well, please ?

Greetings,
Vladimir Nedev

[rita_sobral]

Yes sorry - you might just need to swap trees out but they are from Choas cosmos

[vladimir.nedev]

If I am understanding correctly, you need to control affect reflections/refractions and affect GI separately, like you can in V-Ray ?
So you can enable the fog for reflections/refractions, but not for GI ?

Greetings,
Vladimir Nedev

[rita_sobral]

Affect GI is on by default in Vray as are Reflections and Refractions and the render looks correct if you see my comparison, GI looks correct , fog looks correct, reflections and refraction work on the Vray one...

However you're saying Affect GI is linked to the toggle 'Affect Secondary Rays' in Vantage. Which in theory would mean by standard it is OFF in Vantage? Turning it ON in Vantage actually has a drastic affect to the GI you can see that on the greens in the tree and colours become noticably more different, more vibrant and bright in places, one might even say its not affecting the GI any more. It is also very different to Vrays default (which has Affect GI on) and much more simlar to Vray when you turn Affect GI OFF.

Can you see how that is not making much sense? My testing and comparisons make me beleive 'Affect Secondary Rays' in Vantage is actually turning 'Affect GI' off when toggled but 'Reflections' and 'Refractions' on... It is at least giving that effect visually

If you run through the same tests as I did you will see why I think this...

What I think Vantage is doing

Default
Affect GI = True

Affect Secondary Rays = toggled on
Affect GI = false
Affect Reflections = True
Affect Refractions = True


But my opinon would be that Affect Reflections and Refraction are on by default in Vantage for scattering fog, it makes more sense to have them on by default then off. I can't think of many instances where you would want them off by default.

Thanks

[vladimir.nedev]

Affect GI is on by default in Vray as are Reflections and Refractions and the render looks correct if you see my comparison, GI looks correct , fog looks correct, reflections and refraction work on the Vray one...

In your screenshot, you have "affect gi" = OFF on the second V-Ray render ?
That's what I meant.

Greetings,
Vladimir Nedev

[rita_sobral]

In the second Vray screenshot yes, I just turned Affect GI = OFF the other settings were default (Affect GI is normally on by default, which is what you want).

You can see the pink and the trees are more noticably brighter... The same effect can be seen when you turn ON Affect Secondary Rays in Vantage which doesn't make sense.

[vladimir.nedev]

The main difference in the Vantage implementation of the fog is that it doesn't affect shadow rays, no matter what options you choose.
This was done mainly for performance - there could be a lot of shadow rays and they need to be as fast as possible.
I am guessing this is the reason for the differences you are seeing, but I will have to test a bit more to confirm.

Greetings,
Vladimir Nedev

[rita_sobral]

I just test the shadows parameter in Vray with Affect GI on and then off and the same differences are seen in the GI when you toggle Affect GI... So I don't think it is to do with the shadows... As the pink and the trees are brighter the same as my earlier tests

[rita_sobral]

Hello vladimir.nedev - I have produced another more obvious comparison for you. The difference is crazy for Vantage when you turn on Affect Secondary Rays.... Completely ruins the scene... I've grouped them by similarites Vray x Vantage. The ones on the right with Affect GI OFF in Vray have the closest GI to the Vantage one with Affect Secondary Rays on.

Also included the affect shadows parameter as you said in Vantage this is not implemented.

Whats funny is default Vray and Default Vantage look nearly identical apart from Reflections and Refractions not showing fog.

[vladimir.nedev]

I have some other tasks I need to finish before I can check this more carefully,
but there is a known issue with scatter fog and the light cache.
Can you try disabling the light cache in Vantage and see if that helps with the results ?

Greetings,
Vladimir Nedev

[rita_sobral]

No probelm. Nothing changes when I toggle light cache in Vantage. I think you will find the issue in knowing exactly what settings the 'Affect Secondary Rays' toggle in Vantage is actually turning on or off and whether they are correct... My guess is there is a wrong setting in there...

Default scattering fog in both Vantage and Vray look identical which is good - it's just Refractions and Reflections which are missing in Vantage (visually) - however when you turn on 'Affect Secondary Rays' in Vantage more than just Relfections and Refractions are changing in Vantage - GI is defintely changing...

[rita_sobral]

Hi vladimir.nedev, coming back to this one to see if you have had any more time to look into this issue?

I don't think I explained it well enough in the above but from Vray environment settings, if you turn off the default setting for 'Affect GI' this actually turns on in Vantage 'Affect secondary rays'. You can see this live by just toggling it.

That doesn't make any sense to me? Because if you reverse that action from Vantage then turning on 'Affect Secondary Rays' is turning off 'Affect GI' in Vray Enviroment settings?

I think that's whats causing the huge difference in the scene when you turn on 'Affect Secondary Rays' in Vantage and everything goes weird as per my screenshots above. I think possibly it is turning off Affect GI behind the scenes when you don't want to...

Thanks