ABSTRACT

After the objects are constructed they are usu ally textured which means applying surface properties to the objects

Because this subject is very complex we will work again only with the most important tools and settings This includes materials tex tures shaders and material application

Just as complex is the subject of lighting the objects We will take a look at traditional lighting and also talk about the radiosity calcu lation of light distribution I will use examples to show the advantages and disadvantages of these techniques

Finally we will go through the available options for rendering your work so you can create for example an animation a pre pressready image or a preliminary stage for postproduction

Some of these options are available only when the A

R

is installed a separate module which expands the range of render settings

You will discover though that impressive results can be achieved without this module

The way CINEMA D works is that materials are generated and edited separately from the objects Objects and materials are then con nected by tags which are created in the O

M

Materials and their structuring are produced

inside another manager which is highlighted in the lower part of the layout in Figure

This M

M

has like the O

M

different display modes For now we will not make any mode changes Go

to the F

menu and select N

M

In the same

menu there is the command L

M

which loads materials from an already saved scene With this useful feature materials can be used repeatedly in multiple projects

A gray sphere appears inside the M

M

This sphere presents a preview of our new material as materials cannot be shown in a threedimensional space without being applied to an object

In order to change the name of the mate rial either double click on the name under the preview or use the B

settings in the A

M

that is displayed when the material is selected

In the A

M

you can gain access to some properties of the new mate rial They are separated into channels such as a channel for the color one for specularity and yet another one for the roughness of the surface

There will hardly be a case when all the channels will be used Therefore channels can be activated separately in the B

page of the A

M

Only active channels will be included in the final calculation and can be edited in the A

M

The center of Figure shows some example settings for the color channel shown

Because of the multiple channels and some times very complex settings working in the A

M

can become very crowded The solution is to edit materials in the M

E

Because the M

E

can be opened in a separate window it can be scaled and placed without changing the rest of the layout of CINEMA D The settings are identical to those in the A

M

Figure shows the M

E

in the bottom of the image It can be opened with a double click on the preview of the M

M

Most of the channels of a material are struc tured similarly Many parameters such as

color the possibility of loading images or shaders or the mixing of colors and pictures are identical

For this reason we will go over these repet itive elements once such as the C

chan nel and skip them when looking at the other channels

On the left side of the M

E

un der the preview is the list of all the channels of the material

After clicking on the name the properties of the selected channel are shown on the right side of the M

E

Select the C

channel on the left and take a look at its parameters The purpose of the C

channel is to color the surface of an object All chosen settings will also be influ enced by the virtual light sources which we will talk about later

This is why the color can appear on the ob ject much duller or be completely overpow

ered by the light source when the color selec tor located in the upper right corner of the M

E

is set to a bright red Depending on which color presets were se

lected for the color selector in CINEMA D the RGB or HSV slider will be shown The B

slider can be used to additionally brighten or darken the color By entering val

ues directly into the field it is possible to enter values over

Under these sliders are the T

param eters through which shaders or pictures can be loaded Since we will talk about the shaders later we will first try to load images (see Fig ure )

Use the button with three dots identified with an arrow in Figure A system dialog will open where the image or even a movie can be selected You can use for example the YingYang image from the DVD accompanying this book Then you will be surprised by the di alog shown in Figure

CINEMA D expects to find external data which are used with materials in certain places on the hard drive

One of these places is the start directory of CINEMA D This should not be used for stor ing images as it would get cluttered very quickly It makes more sense to save the neces

sary images together with their scene file in a folder This would be the second place where CINEMA D will look for images

Additionally a T

P

list can be found in P

There a path to an image folder can be specified by clicking on the button at the end of each input field (see Figure )

In our case it is enough to close this dialog by clicking on the N

button The loaded pic ture then stays in its directory and will not be copied into the CINEMA D directory

Now there should be a little preview of the loaded image under the T

list of the C

channel along with some data about the resolution and color depth (see Figure )

At the same time the material preview changed and now has the image projected onto its surface This gives a hint as to how the image will be distorted on a rounded surface such as the preview sphere

Maybe you have noticed that the color chooser apparently lost its abilities That is be cause the C

and T

parts of the channel are used like two layers The T

represents the top layer and covers the color settings (see Figure )

The reason for this is the standard setting N

for the M

M

This can be changed to another mode such as M

or

A

to let the image and color interact with each other

With the M

S

slider the opacity of the T

layer can be changed just like the same option in Photoshop

Figure shows an example using the M

M

In M

mode the color values of the image are multiplied with the color value of the color chooser That way simple color ad justments can be applied directly in CINEMA D without having to change the original im age

Let us take another look at the preview in the upper right of the M

E

The size of the preview image and the shape of the displayed object can be controlled over a con text menu that can be opened by right clicking on the preview

The context menu offers several standard sizes between S

and H

as shown in Figure

For even more control select O

W

… which opens a scalable preview win dow Depending on the complexity of the ma terial it might take a long time to calculate larger previews In this case the A

option in the separate preview window can be deacti

vated and refreshed manually by clicking on the U

button Under the name field of the material there

is a layer menu for sorting the material (Figure ) Figure also shows that I set the pre view size to H

and the shape of the shown object to R

C

This makes it easier to preview the image

The rounded edges of the cube also give a bet ter impression of the shininess of the material

One of the hidden functions is the small menu under the color field (see Figure ) A click on this button opens a list of possible color sys tems and values The color system can always be changed and is independent from the stan dard settings of the program

Click on the color field above the menu when the color chooser of the operating sys tem is preferred

When complex data such as colors or even whole materials need to be copied between channels the easiest way to accomplish this

is to use the C

and P

command for parameters

This and other commands can be found in the context menu which is opened by right clicking on the parameter name Figure demonstrates this with the C

parameter

This explains the most important struc tures of a material channel The difficulty in creating believable materials is not the ability to use the M

E

but rather in se lecting the right combination of different channels and properties

Therefore we need to know which prop erty of the surface will be influenced by what channel Let us take a look at the details of all channels

The job of the D

channel is to weaken the properties of a material The affected properties are determined by the options A

L

A

S

and A

R

EFLECTION The COLOR channel will also be af fected even if it does not appear as a separate option (see Figure )

With the BRIGHTNESS slider the intensity of the channels selected in the options can be re duced The same effect may also be accom plished by changing the intensity directly in the channel This only makes sense when for

example pictures are loaded into the TEXTURE part of the DIFFUSION channel to restrict this effect to certain areas of the material

This is used for simulating a dirty surface or to additionally darken ridges or grooves In this case only the light parts of a loaded image or shader will be evaluated

The color properties of the material also do not change and will only be darkened

The MIX MODE settings are the same as the settings in the COLOR channel They enable us to multiply loaded images or shaders with the value of the BRIGHTNESS slider

Deactivate the DIFFUSION channel again and select the LUMINANCE channel Notice how the surface of the preview cube turns white (see Figure ) This is because the color value set in the LUMINANCE channel is added to the whole material

It does not matter if any part of the mate rial is in a shady spot or brightly lit The shad ing of the object loses its threedimensional appearance because of it In extreme cases the object loses its perspective and only the con tour is visible

Therefore it is important to keep the inten sity of the LUMINANCE channel low It should also only be used in selected parts of the mate rial Later we will learn about different shaders that restrict this channel to certain areas of the applied object

The LUMINANCE channel gains another pur pose when the radiosity calculation in the ad vanced render module is used later on The in tensity of the channel will be used to generate light in the scene

Objects that use the LUMINANCE channel can be used like light sources and illuminate other objects

The LUMINANCE channel can also be used for simulating very hot selfilluminating or translucent materials

Just remember that the intensity of this channel can destroy much of the shading capa bilities of the surface of an object The object will then look in extreme cases two dimen sional

The lower part of Figure demonstrates how intensities can be used to simulate diffuse illumination of objects It appears that the ob ject is lit from all sides This would make sense for example when simulating the diffuse light of the sky

Deactivate the LUMINANCE channel and select the TRANSPARENCY channel of our material The preview cube will then become almost invisi ble (see Figure )

When we look closer we can still see the highlights on the rounded preview cube

This channel simulates the transparency of materials and uses some physical proper ties to accomplish this When the material needs to be accurate then the value of the REFRACTION (the strength of the refractive light property) can be taken directly out of a physics book For example water has a RE FRACTION value of Normal glass has a value between and

The air that surrounds us has a REFRACTION value of When the air is hot this value will increase An example of this can be seen in the desert or over hot asphalt when the air ap pears to shimmer

Try it yourself and put in a value of for the REFRACTION of the material After a short calculation the shape of the rounded cube in the preview can be seen much clearer In addi tion the gray stripe in the background shows how the material distorts its surroundings

In this context there is an optical unit that is used for all transparent and reflective objects The effect actually changes in relation to the viewing angle

This can be tested when standing in front of a store window When looking straight through the window this effect is hardly no ticeable Everything behind the glass is clearly visible

However if you get closer to the window and look parallel along the glass you cannot see anything behind it Instead the reflection in the glass can be seen

The transparency will be reduced depending on the angle between the viewer and the sur face This property can be activated with the FRESNEL option in the TRANSPARENCY channel

When this option is activated the cube loses its transparency on the surfaces that are angled further away from the viewer These surfaces now show more of the settings of the COLOR channel

The influence of the COLOR channel can be increased by activating the ADDITIVE option

However this often results in an extreme brightness of the surface as the brightness of the COLOR channel and the TRANSPARENCY channel are combined

The degree of transparency can be con trolled by the brightness of the color value or the brightness of the loaded shader or image In this manner the color values are evaluated again

That way for example colored glass can be created where the degree of transparency is controlled by the brightness of the color

Figure shows all these settings again in a series of images

The TRANSPARENCY channel can also work with images or shaders so let us try it out

When an image was used in another chan nel and should also be used in this channel it does not have to be loaded again by clicking on the threepoint button

Use the threepoint button in the TEXTURE area of the channel instead (see Figure )

In this menu there are the commands for loading and deleting an image and it has also a BITMAPS entry Under this entry all the previ ously loaded images and movies are listed which can be selected by clicking on them Load the YingYang symbol we used previously in the COLOR channel

On the preview cube notice how the TRANSPARENCY channel applies images The darker an area is in the image the less trans parent the material will be on this spot Com pletely white areas will be transparent (see Figure )

The colors of the image are evaluated too and the transparency is colored accordingly

Gradients can also be used to gradually raise the transparency

COLOR and TEXTURE settings as we already know can be combined with the MIX parame ter for example if we only use a black and white image to control the intensity of the transparency and additionally want to color the object with the COLOR value

The settings for DISPERSION are new This means the spreading of light rays in a transpar

ent material which can be compared to a rough surface or frozen water The irregularities of the surface will further distort elements that are located behind the transparent objects

The transparency might be completely gone when extreme settings are used

The strength of this effect is controlled by the DISPERSION setting A value of will deacti vate this calculation completely In this case the parameter beneath will therefore be grayed out

The higher the DISPERSION value is set the more intense the disturbance is inside the transparency Values between and should be sufficient when simulating realistic materials

The following parameters control the pre cision of the calculation of this effect while having a direct influence on the quality of the display and the time it takes to calculate the material

Because additional calculation rays have to be sent through the material their quantity will be restricted by the values in MIN and MAX SAMPLES (see Figure )

CINEMA D checks in advance the shape of the surface of the object and selects the appro priate number of sample steps When the sur face is a plane the MIN value will be used Curved or angled surfaces need more calcula tion steps and use the MAX SAMPLES setting

The value for ACCURACY works like a multi plier for the SAMPLES settings When a bal anced setting of the SAMPLES values is found then the quality of the calculation can be con trolled with the ACCURACY value

Because of the extended time it takes to calculate each additional SAMPLE it does not make sense to set all of the values to a high

number and hope for a perfect result Instead the values should always be optimized

We will come across this way of working throughout CINEMA D for example when we use the radiosity calculation

Let us move to the next channel after deacti vating the TRANSPARENCY channel in the list of those available

The REFLECTION channel works almost like the TRANSPARENCY channel Here too the inten sity of the coloring of reflections on the sur face can be controlled by the color value or a loaded image

As shown in Figure the loaded YingY ang image causes no reflection in dark places and maximum reflection in light ones

Here too the DISPERSION settings are avail able which work after the same principle found in the TRANSPARENCY channel This time though the reflection will be calculated to be blurrier (see Figure )

There is a connection between the TRANS PARENCY and the REFLECTION channels by the FRESNEL REFLECTIVITY value on the TRANSPAR ENCY page of the material

We learned earlier about the example of the shop window that loses transparency de pending on the viewing angle and in return gains reflective properties

When both channels are activated the strength of the reflection can be controlled with the FRESNEL REFLECTIVITY value It deter mines how strong the reflection will be at parts that are angled away from the viewer and lets us control individually the blending between transparency and reflection

This effect is already calculated when only the TRANSPARENCY channel is activated without the REFLECTION channel This makes sense be cause there is no transparent material without reflective properties

The ENVIRONMENT channel offers an alterna tive to the real reflections of the REFLECTION channel

A loaded image will be wrapped around the object like a shell That way for example a landscape image can be loaded and a simulated reflection of this landscape will appear on the object which means that reflections of objects can be generated that are not in the scene

How many times the loaded image will be put around the object is determined by the TILES value for both the X and the Y directions This makes sense when abstract images are used and the tiling will be less obvious

The EXCLUSIVE option should be left acti vated when the ENVIRONMENT effect needs to be mixed with real reflections Then the ENVI RONMENT reflection will be deactivated where real objects are reflected in the material Oth erwise both reflections would be calculated on top of each other and would not create a real istic result

This channel has the ability to calculate ob jects as if they are filled with fog Other prop erties of the object get lost or severely reduced when this effect is used which is why this channel is often used by itself

The advantage is that the fog stays within the boundaries of the object This feature can be used for instance when portraying fog in a depression in the landscape or cirrus clouds

The density of the fog can be set with the DISTANCE value This parameter determines the distance at which the fog becomes so dense that objects behind cannot be seen anymore

This presumes that the object that the mate rial will be applied to has the appropriate size

Fog with a DISTANCE value of will not be shown to advantage in a cube with an edge length of The DISTANCE value strongly de pends on the dimensions of the object

The fog can also be colored with the COLOR and BRIGHTNESS settings It is even possible to generate black fog by setting the BRIGHTNESS slider to

We already discovered in the first chapter how timeconsuming it is to model something Imagine having to build an extreme closeup or a large printout of a surface Would you want to model all the grain of a wooden board all pores of a face or all grooves of a CDROM?