White Balance in Mentalray Tutorial 3ds max, This tutorial is brought to you by Ivan Ivanov, Environment Artist, you can follow him on http://vankata.info/
In this tutorial I will talk about the white and white balance, and its use in 3D space as 3ds Max and mental ray.
First, we will gain a better understanding of white balance and white point:
White Balance in Mentalray Tutorial 3ds max
In photography and image processing balance of color is the global adjustment of the intensities of the colors (typically red, green and blue – primary colors). An important goal of this adjustment is to make certain colors – particularly neutral colors – correctly, therefore, the general method is sometimes called gray balance, neutral balance, or white balance.
A white spot (often white or white-denominated benchmarks technical documentation) is a set of color values or color location to serve the “white” in image capture, set the encoding and playback. The different definitions depending on the application required by the target to give acceptable results. For example, photographs can be taken over the buildings are illuminated with daylight bulbs, which are relatively orange. Definition of “white” as daylight gives acceptable results when it comes to color correction of a photo taken with incandescent lamps.
As the sun across the sky, may appear red, orange, yellow or white, depending on their position. This is because sunlight changes the color temperature. The color temperature is a standard method in which inks for use in a variety of situations and with different devices. Color temperatures are usually in degrees Kelvin (K). Note that the term degrees kelvin is often used, but is not technically correct (see below).
For 3D scenes, basically, you have to define what is the color temperature of the lamps to brighten it. In the picture below (from wikipedia) You can see how in a throw some light sources like the other blue. This is because the color temperature of the scene is somewhere around 4000K. Thus, light sources over 4000 will be blue, and light sources below 4000K are going to yellow. The game between the white point of the shot, and the temperature of the light source causes a white (or neutral) light.
So having said that, what’s important to us is to define the white or neutral colors in our scene, depending on the light sources we are going to use (and our goals and desires for a scene lighting.
In this tutorial I will be using a simple scene containing couple objects floating on a ocean surface. In the following scene I used photometric Sun and Sky (a daylight system for mentalray) to achieve a photorealism. Here are the starting materials you are going to need:
When you download this file and open it in 3ds MAX 2009 or up, and hit render (f9) you should get a result like the one above. You should note the light setups, the environment setups, and the daylight position.
Now you should note that the whitepoint for my starting scene is set to 7500. If you check out the “Color Temperatures in the Kelvin Scale” (the first diagram) you should understand that the temperature of the sun at noon is about 5000K to 5500K. Which means that IF your daylight source is up in the sky and IF your whitepoint is set to something about 5500K that should result in the render as a white (neutral) colors. This is important to know as a rule, and then we have to learn how to use it, and how to break it as an artist so we could get the desired results.
Without changing anything I will start progressively to increase the whitepoint just to examine the results:
As you probably notice, when we render our scene with higher value of the whitepoint we get a slightly yellowish shades to our render. That makes the render more like earlier in the morning or later in the afternoon when the sun is lower on the horizon and the light becomes a little more warmer.
Now we have something very similar to the lighting of a clear sky on sunrise or sunset. Naturally, you may come up with way better render and way better overall light setups, whats important for me to show is the nature of the whitepoint and its use for any given scene where you use a daylight system.
Lets try decreasing the whitepoint, just to see what happens. I will start with something lower than 7500K.
Decreasing the white point caused the blue shades to overcome. There almost no neutral light and colors in the render – its because the mismatching of the color temperature of the sun and the render output. This means you don’t have a correct lighting in your scene. Ofcourse, that’s not necessarily bad, its just the truth. You as an artist should use the technology to create the desired output in the easies possible way for you.
Having said that, you could use your daylight system, its exposure control and the whitepoint prefs, in a various artistic ways to establish different mood in your scene, or simply to have a specific daytime, such as early in the morning, noon or night time.
For those of you who have more interest in the subject topic and would like to learn more you could check out the following great tutorial by Jeff Patton here.
White Balance in Mentalray Tutorial 3ds max