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Character Lighting

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Last tested against UDK Jan, 2011
PC compatible

Overview

With any game, human characters are often scrutinized in how realistic or stylized they look. While excellent materials, textures and modeling help; at the end of the day lighting plays the largest role of all. While a lot of the tips in this gem is not 100% science, it often comes down to tweaking things to achieve the look that you want.

Tweaking Skeletal Mesh Component

All of your characters are likely to be skeletal meshes because they often need to animate. To achieve good light results, ensure that you create a Physics Asset for your skeletal mesh and assign it to the skeletal mesh component. This will result in sharper shadows and better lighting.

In this screen shot, all of the skeletal meshes do not have any physics assets assigned to them. The results are okay on first sight.

However, compared to this screen shot where all of the skeletal meshes have physics assets assigned, the shadow casted is sharper and more defined and the overall lighting results on the surface of the skeletal mesh is better.

Related topics

• PhAT User Guide
• Video Training Material on PhAT

Material Tweaking

Further tweaking and adding onto your character materials can produce much better results. Achieving better accuracy per pixel will improve the overall rendering.

Adding detail normal maps

Adding detail normal maps is a simple way to start improving the quality at the sub pixel level. Normal maps will always have a resolution and the light calculations depend on this resolution. If the player moves closer to the material it is possible that the normal maps are filtered linearly. This can result in poor lighting. Detail normal maps help to alleviate this issue.

Adding a detail normal map is done as follows. Scale the detail normal texture by a factor, usually a factor of 10 - 15 works well. Multiply the detail normal by a vector which nulls out the blue channel [Constant(1, 1, 0)]. Then multiply this with a factor to adjust how deep the detail normal map is. Finally, add the results of all of this to your normal map.

In this screen shot, the material used on the character does not have detail normal maps.

In this screen shot, the material has detail normal maps added to it. Here we see refined lighting on some areas of the armor and a small amount on skin surfaces.

Adding fresnel maps

A fresnel map helps to add indirect rim lighting to the character. Indirect lighting is an important aspect to skin shading given that skin rendering often employs sub surface scattering. One aspect of sub surface scattering is that the rims of objects tend to be lit ever so slightly.

Adding a Fresnel map is done by multiplying the results of a Fresnel with a Fresnel map. The Fresnel normal is the normal map that you use for the character. The Fresnel map is simply what color to use, so you could also multiply this with a vector parameter to produce colored Fresnel lighting. In this case, the Fresnel map is a gray scale version of the diffuse.

In this screen shot, the material does not have a Fresnel maps.

In this screen shot, the material has Fresnel maps added to it. As you can see, an artificial rim lighting has been achieved. This gives the skin a shinier almost oilier appearance. It also gives the appearance of more volume to the mesh by adding a highlight to compliment the shadow.

Related topics

• Material Basics
• Materials Compendium

Custom Lighting

It is also possible to implement your own lighting on your character materials to produce a very different result.

This material uses sub surface scattering developed by Miguel A Santiago Jr. based on nVidia's research on sub surface scattering. This is the material created for this which implements aspects of sub surface scattering and portions of the standard Unreal Tournament 3 character material. Click on the thuumbnail to see the entire material layout.

In this screen shot, the standard Unreal Tournament 3 character material is used.

In this screen shot, the new sub surface scattering enabled material is used.

Dynamic Light Environment Tweaking

Light Environments are required to improve the performance of dynamically lit meshes. They also make it easier for level designers to automate the process, which otherwise level designers would have to maintain two sets of lights (one being static lights and the other being dynamic lights). Basically put, light environments increase the performance of dynamically lit meshes. Meshes that use light environments also benefit from indirect lighting produced by Light Mass.

Use Boolean Environment Shadowing

Turning this off improves the shadowing quality but at a performance cost. When this is turned on, it will use cheap shadowing from the environment.

In this screen shot, the skeletal mesh component's light environment has boolean environment shadowing turned on.

In this screen shot, the skeletal mesh component's light environment has boolean environment shadowing turned off. Shadows are more well defined and are more accurate.

Synthesize SH Light

Turning this on will synthesize a spherical harmonical light for all lights not accounted by the synthesized directional light, producing better lighting results at a cost to performance.

In this screen shot, the skeletal mesh component's light environment has synthesize SHLight turned off. Lighting is not too bad. Unfortunately, the red and blue lights within the scene are merged together; which is incorrect.

In this screen shot, the skeletal mesh component's light environment has synthesize SHLight turned on. The red and blue lights within the scene produce distinct lighting on the character.

Related topics

• Light Environments
• Lightmass

World Info Character Light Environment Tweaking

These only affect dynamic light environments that have the bIsCharacterLightEnvironment flag set. This can only be done within Unrealscript. However you can quickly test these settings by using SkeletalMeshCinematicActor within the editor.

Character Lit Indirect Brightness

This increases or decreases the indirect lighting of character light environments that have been lit by any dominant lights. Use this if you want to increase or decrease the overall brightness of the character uniformly.

Character Lit Indirect Contrast Factor

This increases or decreases the indirect lighting contrast of character light environments that have been lit by any dominant lights. Use this if you want to increase the brighter areas by this factor and decrease the darker areas by this factor. It helps to bring out the overall volume and shape of the character.

Character Shadowed Indirect Brightness

This increases or decreases the indirect lighting of character light environments that are currently shadowed by all dominant lights. Use this if you want to increase the overall brightness of characters in shadows uniformly. This can be useful if characters become too dark within shadows.

Character Shadowed Indirect Contrast Factor

This increases or decreases the indirect lighting contrast of character light environments that are currently shadowed by all dominant lights. Use this if you want to increase the brighter areas by this factor and decrease the darker areas by this factor. It helps to bring out the overall volume and shape of the character. This can be useful if characters feel flat when they go dark within shadows.

Allow Light Env Spherical Harmonic Lights

This is a global boolean which enables or disables the ability for dyanmic light environments to synthesize spherical harmonical lighting.

Enable or disable spherical harmonical lighting.

In this screen shot, the skeletal mesh component is able to synthesize spherical harmonical lighting. Looks better at the cost of performance.

In this screen shot, the skeletal mesh component isn't able to synthesize spherical harmonical lighting. Doesn't look as nice, but performance is better.

Overall tweaking

In this screen shot, the world character lighting settings have not been tweaked.

In this screen shot, the world character lighting settings have been tweaked and the character seems to have more volume without having to add any new lights into the scene.

Related topics

• Content Blog
• Lightmass
• Light Environments
• Dominant Lights