Research Journal Lei Yu

ITGM 755 - Interactive Design and Game Development Studio I

Fall 2012

Professor Josephine Leong

Checkpoint 1

Week 1(September 10 -16)

Project proposal

This week I need to find out three interesting topics for doing my thesis. Lighting and Texture are my

favorite part. I also start some Unreal game project these days. By doing Unreal project, I realized the

lighting system in Unreal is quite different with Maya. I want to go further in game engines., so I think

start dig the lighting system or the lighting methods is a good direction.

Three ideas:

1. The Unreal Engine does not calculate bounced or ambient light, and so you need to use tools to

simulate these effects. Consider my background; I have lots of experience and tricks to do good

render for animation films. I think for dig more about Unreal Engine, I might be find something that

already done in animation or visual effect but not have been done in game. A combination of the

two will be a good topic.

For doing this research I need to get involve in Unreal first. So I am planning to start from the Unreal

lightings, then the way of simulation bounced or ambient light in Unreal. After doing this, I hope I

can figure out some branch they are not done in Unreal. At last I will create an environment for this

project.

2. Unreal Engine is a very power tools to use, but the working process is quite different with animation

films. For learning and working with Unreal Engine, I think maybe there are many people like me,

who is not familiar with game process. Working through the process, I will get better work flow with

the game process. To research and compare with others work flow, make the summary and analysis,

might be get a good work flow process.

3. Unreal generates light maps and shadow maps for all objects and lights that do not move during

gameplay. It also has dynamic shadows for moving things. I am interesting for these shadow maps

and want to explore more about these shadows in the game. These topics seem need to start with

basic technique of engine.

Readings

1. Lighting in game environments – the how and whys

<http://www.moddb.com/tutorials/lighting-in-game-environments-the-hows-and-whys>

Talking about the Lighting techniques such as where to place the light in the scenes (Lighting source),

keep things in proportion, Light colors in the levels. Use the mapping examples to demonstrate the basic

lighting mistakes.

After reviewing this article, I became more familiar with the lighting game environment. Lighting is one

of the most important and influential elements in environments. It has the power to make or break the

visuals, theme and atmosphere.

The most basic rule of lighting is that it always needs a light source, and light should appear to be cast by

a source. Also to be avoided is lighting that is out of balance with the size of the source. The brightness

of the light source and the brightness of the lighting in an area must be balanced and appear equal.

1600K is sunset and sunrise and 1800K is a candle. 2800K is a regular light, 5000K is midday sun and so

on. A warm blue and a cold red contradict what you will read in a few pages about the warmth of a color.

Emotionally, on the other hand, red probably feels warmer than blue. Common color associations are at

the base of that feeling. In fact one color is not enough most of the time; at least two colors are needed

or else creating contrast will be impossible. The palette of colors to use is very small and mainly consists

of yellow, orange, blue, cyan, red and a tiny bit of green. To use two main light colors such as blue and

yellow and then a third color, like orange, to give extra contrast and difference to a few special elements.

The third color is to prevent the two main colors from becoming repetitive.

The type of color combinations: Warm and cool color ;Strong and easy color (Aggressive red, orange and

yellow, Easy color are blue, green and purple); Light and dark (turn to the grayscale)

The best combination of colors to use in lighting is yellow with blue and all the variations on it (for

example orange-blue and yellow-turquoise).

It is very neutral so lowering the saturation of a color can neutralize the effects a little and that can be

useful.

2. Lighting part in Mastering Unreal technology

Busby, Jason, Zak Parrish, and Jeff Wilson. Mastering Unreal technology. Indianapolis, Ind.: Sams,

2010. Print.

After review lighting part of this book, I learned how various types of lighting and shadows work

together in Unreal Engine 3. Lighting an small environment may seem simple, but for the realistic levels,

requires the multiple lights of different types and settings to achieve the effect.

Workflow Tips:

Keep the amount of dynamic shadows, either cast by dynamic lights or by static lights on dynamic

geometry, to an absolute minimum.

Light environments should be used whenever possible in place of dynamic lighting and shadowing.

Use subtle ambient or bounce lighting or modulated shadows to avoid super black shadow.

UDK custom Real time Ambient Occlusion

Week 2(September 17 -23)

Proposal

This week I need to start research different ways to simulate bounced or ambient light in Unreal. Like

ambient occlusion. I also need to get in to Unreal Materials. After doing research, hope I can narrow

done my first topic and get some specific points.

Readings

3. Ambient Occlusion and UDK

http://rog.gameslate.com/2011/04/ambient-occlusion-and-udk/

The testing of ambient occlusion features of Lightmass. Ambient occlusion adds shadows to the corner

and seams. But there is an issue, when the texture compression turned on it will look muddy, pixelated.

UDK doesn’t seem to have controls over how much compression is applied for lightmaps. It’s either on

or off. There is other quality-related setting. Edit: Higher resolutions on the lightmaps helps, but when it

gets close to the same quality, the file size is even greater than uncompressed.

Possible solution:

1. Make a tool allow changing the value of compress. (research on Lightmass, how it’s function, is

that possible to make this kind of tool)

2. Bake ambient occlusion in 3D software (Maya) Worried about the consistency between meshes.

4. Lighting part in Mastering Unreal technology

Busby, Jason, Zak Parrish, and Jeff Wilson. Mastering Unreal technology. Indianapolis, Ind.:

Sams, 2010. Print.

After review Material part of this book, I learned materials control the final look of every object.

Without materials, object in Unreal are only low-polygon. The simplest way to think of material in game

engine is as a paint that is applied to surface of object. Like Maya, Unreal material is very power, it

allows user to create.

5. Unreal Ambient Occlusion

http://www.chrisalbeluhn.com/UDK_Ambient_Occlusion_Tutorial.html

This is a tutorial for how to make ambient occlusion in Unreal. It explains the working process and

compares two different setting for the result. Good map example for better understand occlusion

exponent.

It also talk about Lightmass and Postprocess for simulate the ambient effect. I am planning to start

this part next week.

Checkpoint 2

Week 3(September 24 -30)

For simulate the bounce light such as ambient occlusion, it seems a lot of work already done in the area

and they got very good effect. I think it well be good to move on the other topic this week. I got some

new ideas from the professor, such as object reflection, and sky light, bounced with the object and the

lighting behavior in different weather condition. This week I start with the light function.

Lightmass Static Global Illumination

http://udn.epicgames.com/Three/LightmassTools.html

Lightmass creates lightmaps with complex light interactions like area shadowing and diffuse

interreflection. It is orthogonal to the rest of the rendering pipeline (dynamic lighting and shadowing), it

just replaces the lightmaps and static shadow maps with higher quality ones.

Light Functions

Lights functions are mathematical representations of how lights should illuminate the scene in Unreal

Engine 3. Light functions allow you to create more interesting lighting set ups, to achieve flicking lights,

masked lights and strobing lights, textured lights. It uses unreal material system. Like the projector, it

can project the texture or color on to s surface and it great for faking advanced lighting effects. Also,

because light functions uses the material system, these light functions can be instanced for variations.

http://www.hourences.com/tutorials-ue3-light-function/

This article gives an easy tutorial to set up the flashing and pulsing lights by using light functions. It

explains what light functions are and how they can be used in Unreal Engine 3.

http://udn.epicgames.com/Three/LightFunctions.html

This article gives technique description for the light Functions. It makes the comparison between Decals

and light functions. It also describes what material expressions can be used and what type of lights can

be used for light function. At the end part, it gives an unreal script light function tutorial.

http://udn.epicgames.com/Three/DevelopmentKitGemsUsingLightFunctions.html

This article demonstrates a variety ways light functions can be used in game, such as textured strobe

light (flash a scene with a texture projected out from the light vector, usually use as causative from lights

in water), neon strobe light (use the light function with a spot light), textured flickering light (the room

to flicker but with shadows being casted randomly), cube mapped light (use when the light has multiple

directions).

Week4 (October1-7)

Continue with the effect of light function, there’s other ways to create the same effect such as surface

reflection. This week my research start with surface reflection and goes more deep in Lighting and

shadows and my focus is on character lighting. Try to find more ways to enhance the character lighting.

Surface Reflection

A strong or subtle reflection is required to give more realism to the game. There are many ways to

generate real time reflections now. Some of them are very simply and more power then be used in

materials.

http://udn.epicgames.com/Three/DevelopmentKitGemsCreatingDistortedReflection.html

This article gives new way to generate distorted reflection. By using this way, it seems very easy to

create real world reflective materials such as mirrors, marble or metal. The steps are creates a render

target first and then create the scene capture reflection. The render target is the viewpoint of render

screen. Change some scene capture reflection settings. This article also has the examples for create

reflection on mirror, marble and metal.

Light Environments

Light environments are required to improve the performance of dynamically lit meshes. They also make

it easier for level designers to automate the process. Put the light environments increase the

performance of dynamically lit meshes.

http://udn.epicgames.com/Three/LightEnvironments.html

This article gives a good explain about light environment. Why we need light environment in game and

how does light environment work. Without light environments, Level Designers are forced to maintain

at least 2 sets of lights, static-only lights and lights affecting dynamic objects. Overlapping between

these is often not possible because too many lights affecting the dynamic objects incurs a performance

hit, and only using some of the static lights on dynamic objects results in incorrect lighting on dynamic

objects and reduces the flexibility of the lighting system.

Character lighting

Human characters are often represent how stylized and realistic the games look. With the good

materials, textures and modeling help, the lighting plays the largest role of all. There’s several ways to

tweak things to make a better look.

http://udn.epicgames.com/Three/DevelopmentKitGemsCharacterLighting.html

This article gives some ideas for enhance character lighting. Tweaking skeletal mesh component such as

assign physics assets to skeletal meshes will get the better shadows. Tweaking and adding onto your

character materials can produce much better results. Achieving better accuracy per pixel will improve

the overall rendering. Add detail normal map will get more details on the surface.

Directional Rim Light Effect

http://kevindeadrick.com/?p=2173

This article covers in detail the concept and implementation of a directional Rim Light Effect. Rim

lighting is a technique most frequently used on dynamic objects and characters in order to better define

the object(s) silhouette and separate it visually from the surrounding environment. In most 3D rendering

systems, the typical expression of a rim effect will involve using a dot product between the Camera

Vector and the Surface Normal.

Material Examples

http://udn.epicgames.com/Three/MaterialExamples.html

This article covers several types of surface effects that can be created with material system. These

examples provide ideas and insight into creating similar effects or completely new effect. The concepts

and techniques such as specularity, environment maps, mask, bump mapping, transmission, edge

lighting and parameterization are cheap ways to create effects.

Materials Compendium

http://udn.epicgames.com/Three/MaterialsCompendium.html

This article is a reference for all material expression nodes available in the material editor. Material

Expressions are the building blocks used to create fully functional materials in Unreal Engine 3.

Checkpoint 3

Week5 (October8-14)

A review about Unreal Engine 4(elemental demo)

http://www.youtube.com/watch?v=dD9CPqSKjTU

Bouncing light dynamically and shadowed sub-surface scattering just doesn’t quite say it the way you

hear it said. The centered upon the use of real-time reflections, pinpointed lighting and shadowing that

works at a pixel level.UE4’s fully deferred renderer and use of global illumination, which allows reflective

decals on each pixel to interact or absorb light as it should, even with multiple or moving light sources.

Illuminated Pixels

Wissler, Virginia. Illuminated pixels. Clifton Park, N.Y. Delmar , 2011. Print.

Part 1&2

The book explores the why, what, and how of lighting, integrating classic concepts with modern

techniques, explaining the importance and the application of them. By discussing first concept, then

how concept is applied through specific techniques. It’s has very good learning curve to introduce the

computer generated light types and lighting techniques.

UDK™ Game Development

Thorn, Alan. UDK game development. Boston, Mass. Course Technology PTR, 2012. Print.

Light Part

Attempts to improve the realism of 3D graphics and their real-time performance on consumer hardware

have often involved attempts to improve lighting systems. The lighting part in this book concentrates

more technical problems and obstacles to achieving realism in real-time games. It talks about the

algorithms or techniques for faking lighting effects or for improving the way lighting is calculated. It also

focus additive color space of light, direct and indirect illumination models, vertex-based and per-pixel

lighting, normal mapping, and lightmapping, as well as the more practical features of point lights, spot

lights, directional lights, and Lightmass. It also considered the subject of emissive lighting and light

functions.. It has a very good definition about illumination and lighting.

Set lighting technician's handbook : film lighting equipment, practice, and electrical distribution

Box, Harry C.. Set lighting technician's handbook film lighting equipment, practice, and electrical

distribution. 4th ed. Amsterdam: Focal Press, 2010. Print.

This book gives much practical technical information, useful techniques and aesthetic discussions for

setting lights. It describes tricks and techniques for operating a vast array of lighting equipment.

Week6 (October15-21)

Unreal Character Development

http://www.3dtotal.com/team/Tutorials_3/Unreal_tournament_tutorial/Unreal_tournament_tutorial_

01.php

This tutorial takes through all the necessary steps to create and develop a character for Unreal Engines. .

I walked you through each step from concept design, an overview of low-poly modeling, un-wrapping,

texturing, rigging, animating, and importing your character into Unreal. It’s a good work flow example

for character pipeline.

UDK™ Game Development

Thorn, Alan. UDK game development. Boston, Mass. Course Technology PTR, 2012. Print.

Shader part

The focus of this part was on materials, mapping, textures, and material instances. It talk about the

algorithm of how material output a rectangle of pixels used to shade the surfaces of geometry. It also

talk about Mapping refers to the instruction set used by the UDK to wrap a rectangle of pixels around a

three-dimensional object. These subjects were not by any means covered in a way that can be

considered comprehensive.

Illuminated Pixels

Wissler, Virginia. Illuminated pixels. Clifton Park, N.Y.Delmar ;, 2011. Print.

Part3&4

Maya® Studio Projects: Game Environments and Props

McKinley, Michael. Maya studio projects game environments and props. Indianapolis, Ind.: Wiley Pub.,

2010. Print.