Question regarding use of Modo native lights

[jonmoore]

I rendered this scene in Vray for Modo (from a Mike James model that's being shared on the main Modo forum) as it's the type of scene that V-Ray excels with and many other renderers fall down.


The lighting setup on the original was interlinked via an assembly so to save time I used the native Modo lights for the first time (always used Vray lights till now) and was pleasantly surprised by the quality of the results. One thing that surprised me was that Vray rendered the inset Modo 'cylinder lights' in the roof without error when using a native Modo camera but failed to render them at all when using the V-ray Physical camera. I wondered why this happened and how Vray is converting the native modo lights in the background.

And following on from that. The native Modo lights originally made use of 901's ALSA sampling setup (samples dynamically allocated from a single setting) and I wondered how this conversion is handled by Vray in the background too.

Whilst I'm here a couple of UI bugs to report too.

- The tooltip on the help button still says "Open the online help for V-Ray for 3ds Max"
- Tear-off popover menus should have a button in the top right that enables the menu to be sticky/closed (as can been seen in the screen grab below)

[vladimir.nedev]

The lighting setup on the original was interlinked via an assembly so to save time I used the native Modo lights for the first time (always used Vray lights till now) and was pleasantly surprised by the quality of the results. One thing that surprised me was that Vray rendered the inset Modo 'cylinder lights' in the roof without error when using a native Modo camera but failed to render them at all when using the V-ray Physical camera. I wondered why this happened and how Vray is converting the native modo lights in the background.

The cylinder light is converted to a V-Ray mesh light with cylinder as the geometry.
It should work with the physical camera, there is nothing special in this case I think. Maybe send me a scene where it doesn't work.
If you don't check "Use V-Ray subdivs" in the "V-Ray Light" tab, the MODO "Samples" parameter is used (the square root of "Samples" is taken as the V-Ray subdivs, so 64 samples is converted to 8 subdivs).

Some of the MODO lights have additional Visible to Camera/Reflection/Refraction options that were introduced in MODO 901.
V-Ray for MODO will ignore those and use the same options in the V-Ray Light tab. Only the "Area" light had these options in previous versions of MODO, so these are used.
Somewhat inconsistent and I will have to fix it at some point.

And following on from that. The native Modo lights originally made use of 901's ALSA sampling setup (samples dynamically allocated from a single setting) and I wondered how this conversion is handled by Vray in the background too.

The ALSA options from MODO 901 are ignored completely at the moment. It is as if you have the Render item "Light samples" set to 0.
The equivalent options in V-Ray are in the V-Ray Main -> Global Options - advanced -> Enable probabilistic lights.
In V-Ray you specify the number of lights to take samples from. I am not sure about the details there.

- The tooltip on the help button still says "Open the online help for V-Ray for 3ds Max"

Fixed. Thank you for telling me, I forgot to change it, when i changed the link.

- Tear-off popover menus should have a button in the top right that enables the menu to be sticky/closed (as can been seen in the screen grab below)

I will see if I can duplicate this behavior, hopefully this is just an option to the command that opens the popover layout.

Greetings,
Vladimir Nedev

[jonmoore]

Thanks Vladimir all useful info and much as I had guessed but good to get things clarified.

The equivalent options in V-Ray are in the V-Ray Main -> Global Options - advanced -> Enable probabilistic lights.

Cheers for the reminder. I completely forgot that probabilistic lights was introduced with Vray 3!

[vladimir.nedev]

The only special thing about the physical camera and lights concerns the option called "Clamp Sky Brightness" in the "Physically-based Daylight" roll-out in the "Environment material".
This option is ignored (considered unchecked, no clamping), when you have a Physical camera. Although changing to a physical camera during RT won't update this properly most likely.

Greetings,
Vladimir Nedev

[BVA]

Thanks Vladimir all useful info and much as I had guessed but good to get things clarified.



Cheers for the reminder. I completely forgot that probabilistic lights was introduced with Vray 3!

I also completely forgot about probabilistic lights...I just added it to the scene I am busy with and it renders less than half the time.
Why is this feature buried so deep in the settings, should it not be on by default?

[jonmoore]

I also completely forgot about probabilistic lights...I just added it to the scene I am busy with and it renders less than half the time.
Why is this feature buried so deep in the settings, should it not be on by default?

From what I remember from playing with it in Max it works better with some light sources than others (it could sometime cause noise with area/plane lights).

This was when v3 was first launched though, so it may well perform more reliably now.

[BVA]

From what I remember from playing with it in Max it works better with some light sources than others (it could sometime cause noise with area/plane lights).

This was when v3 was first launched though, so it may well perform more reliably now.

I think it is on by default in max, if I recall correctly. I used to just increase the amount till there was no noise. Not sure if it is technically right or not but rendered quicker and looked smooth.