V-ray interior too dark and noisy?

[eleftherios_dousis]

Hello all,

I'm a V-ray newbie and trying to understand how lighting works. I have a project for a house which I have modelled in Rhino and currently using the built-in Rhino sun as my light source to generate some basic concept white 'sugar cube' renders using the default V-ray material. While the exterior is nicely lit and the light is very vibrant, the interior is way too dark - it is almost as if the walls are not reflecting any light at all. In a more realistic setting the sunlight/daylight would bounce around the room and light it up.

I have slightly mitigated this by adjusting the exposure on the right hand side controls in post but this emphasizes the bubbly noise on the walls. I have attached a screenshot for reference.

Here are some specs and settings:

Rhino 6 & V-ray 3

Sunlight:
Intensity Multiplier - 0.5
Size Multiplier - 5

Global illumination:
Primary Rays - Irradiance map
Secondary Rays - Brute force

What I am using as a 'camera' is simply my Rhino perspective viewport and saving that under Named Views.

Would someone kindly help me with achieving a less dark interior for internal rendering shots? Also why is there so much noise on the walls? How can this be mitigated? As mentioned, I am a newbie so I appreciate your time and help.

[Micha]

Some thoughts:

* what you see is not so much noise, it are splotches from the IM pass and more IM subdivs helps
* I would recommend to use LC instead BF, the rendering is faster and you get a fast preview per LC pass
* try to get the right brightness of your scene by the lighting (for example the multiplier at the environment) and not the multiplier of the frame buffer (I afraid you get more noise else)

Attached two setups for LC/IM and LC/BF. LC/IM is faster, but you need to adjust the IM subdivs against splotches (30..50 exterior, 50..200 interior). LC/BF doesn't create splotches, but is slower. Against fine noise the noise threshold is needed - preview quality 0,03...0,5, good quality 0,02..0,01.
I used LC/IM several years and I was happy about the fast speed. But now I use LC/BF always.

Sidenote: the GPU mode doesn't provide the IM mode. Only LC/BF or BF/BF is available. The quality is very solid on this ways. But best you use a very powerful CPU or a fast GPU like 2080ti.

[nikoleta.garkova]

Hi eleftherios_dousis

As Micha pointed out here, the splotches on the walls are from to the Irradiance Map pass. We are actually advising users to use Brute Force for Primary Rays and Light Cache for Secondary Rays as this is the most optimal solution in regards to quality vs render time.
You can try to play with the Intensity multiplier as well to get a brighter effect, or alternatively, make the diffuse color whiter if you haven't.

[Micha]

But ... be careful with the white diffuse color - the brightest white at the real world reflect only 80% of the light. So, you should stay below RGB(210,210,210) or you get an unnatural dull looking light transport.

[eleftherios_dousis]

Thank you for your help everyone, I really appreciate it. I will be doing more testing in due course and will update as necessary.

[konstantin_chaos]

Hi eleftherios_dousis,

Please also note that in most current V-Ray versions like Next and V-Ray 5 you have a lot more robust tools to help you illuminate interiors.
- The V-Ray Adaptive Dome light will help quite a bit by bringing direct light into the closed space. You'll not be relying 100% on the GI for the job and it doesn't require a complex setup - https://www.youtube.com/watch?v=WLYp6cKDEsU
- The Auto Exposure feature will automatically adjust the Camera EV to ensure based on any lighting setup - https://www.youtube.com/watch?v=zhSF2R6-ChM
- The default render settings and quality presets are also much more optimal.
- The Light Cache engine which should be used for the secondary light bounces is optimized and improved in various ways
- In V-Ray 5 we even have a tool that can suggest many different lighting conditions for you to choose from. You can then click on one of the thumbnails and the scene will be set up for you.

You can find out more about the latest update here - V-Ray 5 for Rhino announcement

Regards,
Konstantin

[Micha]

konstantin_chaos Do you think the V-Ray ambient light source could be added to Rhino? For example it could be very useful for large closed spaces like shop design renderings. So far I know it's not photo realistic but fast and stable. I hope it can be useful for animations. Could it be added to VfR5 please?

[konstantin_chaos]

We can add Ambient light, yes.
It can be useful for diagrammatic rendering too but I'll still have to think about this.

Another approach that we are experimenting with is allowing the creation of any V-Ray Core light material or texture.
We can then show it with an auto-generated UI and you'll still be able to use it.
You can test this by loading the attached file (in V5).
Unfortunately lights will import in the Asset Editor and will show settings but won't illuminate the scene.
This is intentional and can easily be changed.

Regards,
Konstantin

[Micha]

Great!! You makes me curious and I would like to try it on a scene. So, please make it shine.

[Micha]

...
Unfortunately lights will import in the Asset Editor and will show settings but won't illuminate the scene.
This is intentional and can easily be changed.

Hi konstantin_chaos, any chance to get it running now. A client ask me for an interior animation and maybe this kind of light could help to get shorter render times.

[konstantin_chaos]

Hi,

Sorry, still not.
I'll raise priority of this and you might see it implement soon.

Konstantin

[Micha]

Hi konstantin_chaos,

I'm working on a large air plane interior and it's difficult to get the exterior light through the small windows. An ambient light could be useful to get a basic level of light everywhere. What is with your idea, the basic solution like you described with automatic UI?

[konstantin_chaos]

I'm working on a large air plane interior and it's difficult to get the exterior light through the small windows. An ambient light could be useful to get a basic level of light everywhere. What is with your idea, the basic solution like you described with automatic UI?

Hi Micha,
This is still not possible in the current builds.
I'll raise it's priority.
And, yes, it's going to be done by importing an ambient light with auto-generated UI.

Konstantin

[javierrentas]

Do we have any news on this ambient light feature? I have some projects that I may be able to use it.

Best,