New to V-Ray, comparing renders from modo

[jxl4357]

Hi everyone,

I've been playing around with different settings in V-Ray to see if I can get better renders with less noise. The image I try to compare is the same one I did from modo 902. The left image is a render from modo and right image is from V-Ray.

The settings I use from V-Ray is:

Adaptive
Min shading rate: 64
Min subdues: 1
Max subdives: 64
Threshold: 0.01
AA filter type: Gaussian
Primary Engine: Irradiance Map (saves a lot of time rendering)

Under V-Ray light: I use photon subdivs 500

The image I get rendered seems to be blown out with noise. I want to learn where I can eliminate noise and try to make it clearer and less blurry.

The scene I am using has 3 luminous polygons. There is no material applied.

Any help is greatly appreciated.

[vladimir.nedev]

Can you send me the scene ?

If the luminous polygons are small, it is better to turn them into a mesh light.

Greetings,
Vladimir Nedev

[jxl4357]

Hi Vladimir,

Thank you for the reply. Please see attached.

[vladimir.nedev]

and try to make it clearer and less blurry.

The render is blurry because of the very high value of the AA filter size, set it to something like 1.5 (it was 8 in your scene).

Min shading rate: 64

I don't think this is helping you, since you are using the Irradiance map.
There isn't much noise in the render, since the irradiance map smooths it.
This high value for min shading rate is only slowing down your final render by a lot.
Better reset it to 6.
Or even better reset all the render settings by removing and then adding back the V-Ray Render Settings package.

Under V-Ray light: I use photon subdivs 500

These don't matter unless you are using the Photon Map as one of the GI methods, which you are not.

The image I get rendered seems to be blown out with noise.

If you are referring to the V-Ray render being much brighter than the MODO one, this is because MODO uses only 1 GI bounce by default.
You can set it to 3 or higher to get similar renders.



Greetings,
Vladimir Nedev

[GidPDX]

In my limited tests I haven't seen a case yet where 64 minimum samples would be needed. 30 with a low threshold seems more than enough for most things, but it seems you don't often need that.

You should start ad defaults, or even LOWER than defaults and probably only slowly raise the max sub divs, and lower the threshold to start, only occasionally nudging the minimum samples higher when it seems like you need to feed Vray more.

For edges, I've found gaussian set to filter size of 2 (default) coupled with a minimum sub div of 2 starts getting closer to the feel of MODO.

I'm still really new to Vray so take my suggestions with a grain of salt though.

[jxl4357]

@Vladimir - thank you so much for your help and explanation.

Here's the changes:
1) question: when would "Brute Force" be in use?
2) Changing the Indirect Bounces did not do much. How can I change the "brightness" of the scene for a render, make it darker? Change the gamma of 2.2? It's probably best to change my lights in the scene, right?

@GidPDX - thanks for suggestion. Will try that out too.

[BVA]

How can I change the "brightness" of the scene for a render, make it darker?

Easiest for me is to add a "vray physical package" to the camera, then you can set the F-Stop, ISO etc to your liking.
As for the other settings, I always start my scenes with the default values, they are REALLY working well. I make the following changes though:

I change sampler type to adaptive and then max subdivs down to 4 for my prelims, finals I render between 12 and 16 at most. GI I change to Irradiance (for Primary) and Light Cache (for secondary)

Years ago I used to change a lot of settings but lately vray is so optimized and this is a really good starting point. I rarely need to change anything else. It might be different in your workflow though, I do interiors with "millions" of lights.

PS.... in my experience I find that physical lights works better than luminous polygons, rather try out with area ligths or even mesh lights if needed where ever you can

[John_Do]

1) question: when would "Brute Force" be in use?

When Irradiance Map gives bad results Personally I use always the Brute Force method, it has become really fast for few years, and the new self assessed sampling algorithm makes it really easy to use.

2) Changing the Indirect Bounces did not do much. How can I change the "brightness" of the scene for a render, make it darker? Change the gamma of 2.2? It's probably best to change my lights in the scene, right?

Use the properties of the V-Ray Camera. Check Exposure and you have several settings to tweak it ( F-Stop, ISO and Shutter Speed, like on a real camera ).

[jxl4357]

Loving the help!

Special thanks to @BVA & @John_Do for your help! Just simply applying a V-Ray Camera package did the trick. Love how I can change the scene easily.

@BVA - thanks for advice on the settings and lightning. Will follow those on my workflow.

Here's the changes:

More improvements to do, but with all the help received, I should have a good start.