Making light work: part III

Following on from last monthÝs look at Global Illumination with mental ray, the third part of Darren BrookerÝs four-part comparison of the interior lighting methods available within 3ds Max takes us through three-point lighting.

Our first two articles on the various interior lighting tools available within 3ds Max both looked at Global Illumination; first in context of the radiosity renderer, and then with mental ray. This month weÝll leave GI algorithms behind and look at how to fake the look using the standard lights and a technique called three-point lighting.

The convention of three-point lighting is one that is firmly established in cinematography, and has become one of the main foundations for CG lighting too. One of the principal reasons for this is that the technique helps to emphasise three-dimensional forms within a scene using light.

Unsurprisingly, there are three lights involved in three-point lighting, and each has a specific function. Providing the main illumination in a scene, the key light is the dominant light, or the one that casts the most obvious shadows. The job of fill lights is to model the indirect lighting that is produced by direct light bouncing off an environmentÝs surfaces. Helping to separate the subject from the background, the backlights give a scene depth.

WeÝll start by placing the key light, which represents sunlight coming through the windows to the right of the interior. Create a Target Direct light and once created right-click the Transform button to bring up the transform dialog and type in X:-13m, Y:-17m, Z:12m. Rename this light DirectKey01, then place the target at X:3m, Y:0m, Z:1m. Turn on Raytraced shadows, as these will need to penetrate the raytraced glass material, and give the light a Multiplier of 8.0.

Figure 1. Rendering with primary key light, but because there is no indirect lighting component being calculated you will see a largely black interior.

If you render now you will see a largely black interior, because there is no indirect lighting component being calculated (see Figure 1). All you should see is the direct component of this one single light, as well as the reflective elements within the scene, such as the lighting fixtures, which also have a Self-Illuminated material applied. The next task would be to place the secondary key lights within each of these fittings. Rather than do this manually, choose File > Merge and select the 03threePointLightingCeilingSpots.max file. Select all the spotlights and choose OK.

Select any one of these lights and within the Modifier Panel take a look at the way the light is set up. Firstly, you can see that shadow maps are being used here rather than raytraced shadows, which is primarily because we donÝt want sharp shadows from these lights. You should also notice that the light has Decay enabled and set to start at 2.0m, as the decay from interior light fittings is very noticeable, compared with sunlight which does not decay over the few metres it travels into a room. Additionally, the light has Far Attenuation set to Start and End at 2.0m and 8.0m.