Mar 11, 2012

In this tutorial I will go through a simple, yet effective way to setup a lighting rig using 3ds max and vray.

Before we begin we need to setup the lwf.
Go to “Customize”, “Preferences” and click the “gamma and lut” tab.
Check “Enable gamma /lut correction”, type 2.2 in the field next to “Gamma”.
Under “Materials and Colors” check both “Affect Color Selectors” and “Affect Material Editor”.

Don’t forget that for every texture that you use you need to override it’s gamma like in the screenshot bellow:

If you need a more in depth explanation regarding linear workflow, check out my lwf tutorial that I have posted some time ago. However, the steps above pretty much cover the essential.
1)    Click the “create” button and select “cameras”. From the drop down menu select “vray” and click on “vray physical camera”. You can now create and place the camera wherever you want in the scene.
2)    Now we will create the sun. Click again on “create” and choose “lights”. Again, from the drop down menu select vray and click on Vray sun. You can now place the sun and it’s target in your scene.
When you will be asked if you would like to “automatically add a Vray Sky environment map”, click “yes”.
The position of the sun source is directly related to the time of the day. Bellow are 2 examples of renderings with different sun positions (while keeping the rest of the settings identical).

VraySun parameters
1) -turbidity
This parameter affects the color of the sky and overall atmosphere in a way the dust affects atmosphere. A higher turbidity value simulates a larger amount of dust and makes the rendering look more yellowish. See examples bellow:

2)  -ozone – ranges from 0 to 1. Lower values are supposed to make the sunlight look more orange, while higher values should make it bluish. I always prefer to leave this as default.

3) -vray sun size multiplier
– a value of “0” produces very sharp shadows, while higher values makes them softer.

4) -shadow subdivisions – if you are using a higher value for the vray sun size you will need to increase the shadow subdivisions as well, otherwise the samples will be visible.
5) -Intensity multiplier – needless to say that higher values results in higher sunlight intensity
Having this said, the settings that I usually use for creating a day rendering are:
-intensity 1
-turbidity 4
-size multiplier 5
-shadow subdivisions 9
If you don’t like the vray physical camera, you can use a standard one as well, but you need to decrease the intensity to somewhere around 0.01
Bellow is a rendering that was done using the settings above.

As you can see, at the moment it looks a bit dark and washed out. You can either play with the curve in vray virtual frame buffer, or start tweaking the vray camera settings.
Vray camera parameters
I always prefer to further adjust the image from the vray camera parameters.
There are 3 main parameters that affect the lighting/atmosphere: F-number, shutter speed, and film speed.
1) F-number
This parameter determines the width of the camera aperture and therefore it affects exposure. Higher values produce darker images, while lower values brightens the images

2)Shutter speed
This parameter determines the amount of time the film is exposed to the light. It is calculated in “inverse seconds” therefore higher values produce darker images.

3)    Film speed
This parameter determines how sensitive the film is to the light. Higher values produce lighter images, but the downside is that the higher the sensibility the more “grainy” the image will look.
For daylight exterior renderings it is recommended to keep this at 100.
There are several other parameters that you can touch (like custom white balance, vignetting, etc) but you can have more control if you do this in photoshop.
In conclusion, even though there are no “universal settings” for the vray camera, whenever I do an exterior daylight rendering I start with the following settings, and depending on the scene I may need to tweak them a little further.
F-number – 7
Shutter speed – 120
Film speed – 100
Rest of the parameters – default.
Bellow is the rendering done using these parameters.

In the next part of this tutorial we will talk about image based lighting, so stay tuned.

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