Tutorial_Various_Lightning_Technics.pdf

Content:

1. Introduction 01

2. Three Lights Scene 02

3. The Sphere of Lights 06

4. Mental Ray 10

5. An Example 11

6. Link List 15

1. Introduction

In this short article we want to

explain the 3 basic methods of

lightning. This tutorial is focused

on bloody beginners and should

help them to choose the right

lightning technic for their projects.

The three lights scene is very

easy to handle: Just place 3

different spot-lights around the

scene. Although the results look

quite good for CG-art, real

ÐfreaksÑ canÓt be satisified with

this kind of lightning, me included.

Therefore another solution exists.

The ÐSphere of LightsÑ, which

is a a dome of lights that give

nice soft shadows.

The results are quite amazing but

the script creates hundreds of

spotlights around the scene which

make the handling a bit

complicated.

The last solution is Mental Ray a

Renderer that comes with

3dsmax6. With the help of this

renderer you can create

photorealistc effects that are not

feasible with the normal scanline

renderer

Lightning is one of the most

important things in CG-art. Ever

since CG exists, artists wanted to

create perfect copies of real life.

One big problem was lighting up

the scene.

Where to put the different spots

to get a half-decent result?

The three lightning techniques

are: The three lights scene, the

sphere of lights and lightning

with mental ray.

2.1. The Key Î Light

color. Key-Lights have to create

shadows, therefore you have to

activate them.

The Key-Light is responsible for

the main illumination of the scene

and defines the angle where the

basic light comes from.

In the picture on the right, the

Key light is placed on the right

hand side of the camera. It is the

strongest light in the scene and

therefore creates the darkest

shadows.

Here you can use a multiplier-

amount of 1 and a bright white

In real life, (in most cases) the

KeyÎLight comes from top (the

sun or the lamp in your living

room) so you can take it as a rule

of thumb to place the KeyÎLight

always above the object.

You can easily remember to place

it in an angle of 45 from the

objects front and height.

2. Three Lights Scene

The three different lights are:

the Key-Light

It is true that there are absolulty

no lightning rules and that every

scene has its own lightning

positions although there exist

three types of basic-lights which

can be found again and again.

the Fill-Light and

the Back-Light

The picture seen above was found

in the book: 3d Studio Max R3

Î Professional 3d Effects from

Jon A. Bell and describes the

three different light positions very

well.

ItÓs the basic lightning technic

used in 3dsmax.

For example: if your object is

placed 0/0/0 and your camera is

placed 0/100/0, itÓs a good idea to

place the Key-light at

100/100/100 or

Î100/100/100

so: either left- or right hand side

of the camera and a bit above.

2.2. The Fill Î Light

They illuminate only parts of the

object that are not directly

effected by the Key-Light, but

would be effected with the help of

other objects in real life.

With the help of the Fill-Light

you can also fake reflections or a

second light source.

your scene settings.

The FillÎLight supplements the

Key-Light. It creates a smooth

atmosphere and brings out the

details of the objects. By doing so,

it dimly lits the dark parts created

by the Key-Light.

Just take a look at the picture on

the right. With the help of a

second Spotlight I was able to

light up the scene.

Fill-Lights have no fix place and

no fix amount as Fill-Lights

simulate the light that is reflected

from other objects. The first pic

on the previous page shows the

Fill-Light on the left hand side of

the camera.

You can use eihter Spots or

Omnis for Fill-Lights and you

should change the bright white

color into a soft tone.

The Key-Light is always the first

light to be created, although using

only the Key-Light will result in a

very flat looking image. Just take

a look at the picture of the teapot

on the previous page where I only

used a simple Spot representing

the Key-Light.

Fill-Lights are NOT as strong as

Key-Lights. Use a Multiplier-

amount of 0.5 (or lower) for Fill-

Lights, but that really depends on

In real life every object immits

and emmits parts of the light. The

emmited light lights up other

objects and gets immited and

emmited again. This effect is

called ÐradiosityÑ

You can see that the shadows are

very strong and parts of the pot

are completely black. So: using

only the Key-Light makes your

scene look really dark. To get rid

of this effect, we have to create

the Fill-light.

As a matter of fact this kind of

effect is rather complicated to

simulate within a 3d software.

To simulate ÐradiosityÑ, FillÎ

Lights are used.

Normally Fill-Lights are too weak

to produce shadows so you do not

have to activate them. If you

really want to use shadows you

should change the shadow

parameters. Lower the Ðobject

shadow densityÑ to 0.5 or even

lower. At the same time you have

to raise the ÐSample RangeÑ to

10 (again: those values strongly

depend on your scene)

2.3. The Back Î Light

With the help of those settings

you should be able to create the

basic lightning of your scene.

have some light coloring.

The Back-Light illuminates the

boarders of an object to highlight

it from the background.

Thus, Back-Lights help to define

an object.

The Back-Light defines the back

of your objects by illuminating the

boarders.

Like the Fill-Light it is used as an

indirect light-source and can only

create soft shadows.

The Key-Light always represents

the main lightsource and creates

the darkest shadows.

The Fill-Light helps to light up

the whole scene, especially the

areas that are not illuminated by

the Key-Light. It can only create

very soft shadows and should

Back-Lights are placed

diagonally opposite the Key-Light

and a bit above. You can use the

same settings similar to the Fill-

Light.

Again, the Back-Light creates

only very soft shadows so keep in

mind to raise the ÐSample RageÑ.

Beside those three main Light-

Types, there exist a lot of others

as well.

With those settings the Fill-Light

will produce very soft shadows.

Higher sample range causes

soft-edged shadows

Contrary to the Fill-Lights, you

should always use Back-Lights

as they increase the realism of

your scene.

The picture on the right shows the

final result of my small sample

scene with all three lights

activated.

Other types are artificial light

sources like desk-lamps,

headlights, flashlights or open

fire. To simulate these kinds of

light-sources you should use Lens-

Effect-Glow or other Video-Post-

Stuff to illuminate the object (ex.:

a bulb)

BUT there exists at least ONE

rule you must take care of:

In this short article I do not want

to differ between indoor and

outdoor lightning as this topic

could fill libraries.

All I can do is to give you a short

overview and some rules of thumb

you should take care of when

working with 3dsmax and lights.

NEVER ever place a light directly

behind the camera!! Although the

light would be very consistant it

would ruin the 3rd dimension. By

placing a lightsource behind the

camera you would create the

effect of a flattened image.

If you do not know how to work

with Video-Post please use the

online help of 3dsmax ( ÐF1Ñ )

Keep in mind that lights have the

aim to create a dimension either

by lighting up only parts of the

objects or by creating real

shadows.

As I told you before:

In real life every object immits

and emits parts of the light. The

emited light lights up other

objects and gets immited and

emited again. This effect is called

ÐradiosityÑ

In summary it can be ascertained

that the three-point-lightning is

basically used to display 3-

dimensional objects in a 2d

picture. In an illuminated scene,

every lightsource serves a

purpose (Key-Light, Fill-Light or

Back-Light).

Well, thatÓs it from the simpliest

form of lighting up a scene in

3dsmax. You can use this form of

lightning if you have created just

one model and want to present it

like a photographer in his studio.

By creating more complicated

scenes, the lightning gets more

complicated as well.

It is hard to create a Ðradiosity-

like-effectÑ with just Fill-Lights.

The problem is that those

guidelines are very flexible as

there exist no rules in art.

To get the effect of radiosity a

little script exists which can create

a Ðsphere of lightsÑ.

The Ðsphere of lightsÑ is the

next step towards reality.

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