The rule of three

09/06/2008 | 519 views

Good lighting isn’t simply a matter of making sure that every object in a scene is illuminated. The last thing you want is for your renders to look as flat as the screen they are viewed on, so your lighting set-up also needs to ensure that the three-dimensional form of each object can be read clearly. This is where basic three-point lighting, a system derived from traditional cinematography, comes in.
Flat-looking output is most likely to occur when a single light source is placed behind the camera: a situation analogous to a photographer using nothing more than a camera-mounted flash. In contrast, three-point lighting treats light more like a modelling tool. The three light sources of which it consists – the key light, the fill light and the back (or rim) light – all serve different purposes, yet work together to emphasise shape and form.

Providing the main illumination in a scene, the key light is the dominant source, casting the most obvious shadows. It can represent a practical light in a night-time shot, sunlight for outdoor work or sunlight entering through a window for daylit indoor shots.

The key light defines a scene’s dominant lighting, giving the biggest clue as to the location of the presumed light source.

The job of fill light or lights is to model indirect lighting produced by direct light bouncing off an environment’s surfaces. The primary fill is usually placed on the opposite side of the subject from the key, where it opens up the lighting and reduces the shadow density. The backlights give a scene depth and help to defi ne the subject.

In this tutorial, you will learn the basics of three-point lighting by examining a simple interior scene and setting up the lighting to produce a flattering set-up. Full-sized screenshots and supporting files are included on the CD to help you on your way. This article is a condensed version of the one that appears in the book Essential CG Lighting Techniques with 3ds Max, published by Focal Press.

Step 1

Open the 3PointLighting.max file from the cover CD. The scene currently has no lights set up, so first you should place the key light. This is going to represent daylight coming from a window to the left of the table, as seen through the camera. For this you need to create a Target Directional light, anywhere in the scene, naming it ‘directKey’. The settings are shown in the screenshot above.

Step 2

Move the light somewhere around X:-110, Y:150, Z:90, with the light’s target somewhere around the eggcup. Give this light a Multiplier value of 0.9. Turn on shadow casting by ticking the Shadows checkbox. Clicking the colour swatch, give the light a yellow tint – R:237, G:229, B:188 – to represent early-morning light as you’d see it on daylight-balanced photographic film.

Step 3

In the Directional Parameters rollout, change the light from Circle to Rectangle, set the Aspect to 0.5 and change the Hotspot/Beam and Falloff/Field values to 40 and 50. Right-click any viewport label and select directKey from the Views submenu. Because it represents the sun, we won’t set any attenuation: the intensity of sunlight would not decrease noticeably over this small distance.

Step 4

If you render now, you’ll notice that the edges of the shadows look jagged and too well-defi ned. To correct this, open the Shadow Parameters rollout and change the colour to R:20, G:12, B:0 and the Density (Dens.) to 0.9. Within the Shadow Map Params rollout, raise the Size to 1,024 and the Sample Range to 10. Render again, and your shadows should look much better, if still too dark.

Step 5

Time to create fill lights. With [Shift] held down, use the Move tool to drag the light in the Top viewport. Release and select Copy from the resultant dialog, changing the light’s name to directFill01. Now move the light to illuminate the shadowed side of the objects (somewhere around X:-140, Y:-10, Z:60), change the Multiplier setting to 0.3 and give it a slightly more saturated orange colour.

Step 6

Untick the Shadows checkbox. Within the Directional Parameters, change the light to Circle and tick Overshoot. Within the Advanced Effects rollout, untick the Specular checkbox. Now render, and you should see that the shadows are more open. Adding more fill lights will open up the shadows further and mimic the light that would be bouncing around this environment.

Step 7

[Shift]-drag a copy of your fi rst fi ll and move this to X:-110, Y:-30, Z:60. Change its Multiplier setting to 0.1. Another copy with a Multiplier of 0.1 should be placed at X:-40, Y:110, Z:60. One more copy, placed at X:-120, Y:100, Z:60, should open up the shading adequately. If you render now, you’ll see that the overall level of illumination is good, but the undersides of the plates look a little too dark.

Step 8

[Shift]-drag a copy of one of your fill lights to underneath the table. In the Top viewport, move it centrally to its target near the egg, so it’s pointing directly upwards, mimicking light bouncing back up off the table. Give this a Multiplier of 0.3 and make it a similar colour to the tablecloth. If you render now, you should see that the undersides of the plates look a lot more realistic.

Step 9

Finally, add a back light by copying one of your fi lls to X:15, Y:-20, Z:60. Give this the same orange colour: it will represent the light bouncing from the far wall. To finish, go to the Display tab: if you click the Unhide by Name button, you can unhide the extra light in the scene. Turn it on to add a subtle steam effect to the mug. And that’s it: your first three-point set-up!

Darren Brooker

Darren Brooker is a BAFTA award-winning lighting artist who has worked at many top UK studios, including Pepper’s Ghost and Red Vision. He works for Autodesk as a product specialist www.autodesk.com

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