160 Virtual World Design
FIGURE 8.2 Chart showing the components of a “Magic Sheet.” In the top half, the lights are identied by name, loca-
tion, color, range, scripting, type of source, and given special notes, if necessary. In the lower half is a schematic map,
showing where each of these lights are placed on the sim.
161Lighting in Virtual Environments
8.5.2 shaders and TexTures and hoW They maKe maTerials
Now, if you remember that the color on the surface of an object occurs because it holds on to all the other
wavelengths and only lets you see the color wavelength of the material, you are beginning to understand how
shaders work. This kind of selective specicity extends to all manner of surface properties in a virtual world,
and by controlling them you can affect the quality of “perceived” light in a scene. Imagine the difference in a
sphere that looks like blue felt versus a sphere that looks like blue glass. Because of the soft surface on a felt
sphere, you may not actually be able to see a highlight on the surface, and the lighting would seem general and
diffuse, as if from an overhead uorescent panel. On the glass sphere, you may see very bright highlights on
the surface, showing you the positions of all the lights around it. These extreme examples are to make the point
that the choices you make in the properties of the surfaces on your objects in a virtual environment are a vital
part of the lighting design. In virtual environments, all of the 3D surfaces are covered with materials or shaders.
Just so you have a clear understanding of the terms and there is no confusion between the term shader
and the related terms of texture and material, let’s look at the differences in meanings for this terminology.
8.5.2.1 Defining Shaders, Textures, and Materials in Second Life and OpenSim
1. A shader denes the look of a surface of an object. Shaders make up the underlying surface of a
material without color or just a basic color tint. They have little “character” other than how shiny,
transparent, or smooth they make the surface of a prim or object look.
2. Textures can be added to the shaders to make a surface take on more detailed characteristics such
as wood grain, mineral ecks, or animal skin coloring.
3. Materials are the combination of textures and shaders and can be stored on prims in Second Life or
OpenSim as shown in Figure8.3. The menu for creating them is found under the Texture tab of the
Build/Edit menu.
Beautiful models covered with “baked” or prelit textures are almost indistinguishable from models lit
with real-time light. The limitation to this process is that your shadows are static and especially noticeable if
you have any moving lights or a sun/moon cycle. A walk down the street on a sunny day will show you how
highlights move across the surfaces as you change your point of view and how shadows move in response to
changes in the lighting in the environment.
8.6 ENVIRONMENTAL MENUS AND SHADERS IN SECOND LIFE AND OPENSIM
Shaders in Second Life and OpenSim are inuenced by the Graphics settings controlled by Firestorm. The
environmental settings you see in the Avatar/Preferences/Graphics menu when you have the quality set
as medium or higher include shaders such as Lighting/Shadows and Ambient Occlusion. These Advanced
Lighting shaders greatly affect the look of the materials in the world, as you can see in the lower panel of
Figure8.3, and they are in turn affected by the WindLight settings of the entire environment. InSecond
Life and OpenSim, after you have applied shaders such as transparency, glow, shininess, and bump textures
to an object, you can then universally affect the appearance of your water, land, sky, and all the objects
on it with the choice of different overall settings in the Avatar/Preferences/Graphics menu and in the
World/Environment/Editor/Environment settings menu.
Compare the two menus so that you understand how they differ and overlap in functioning. InFigure8.4,
you can see the Advanced Lighting and Shader controls under the Avatar/Preferences/Graphics tab. Below
it is the World/Environmental Editor/Environmental Settings menu, where you can customize your sky and
water environments and the overall lighting of the scene.
162 Virtual World Design
FIGURE 8.3 Screen grabs from OpenSim showing a comparison of four spheres with the following shader/material
effects: (1) blank texture/white color, (2) 50% transparency, (3) 0.01 glow, and (4) low shine with bump map (top panel).
Also shown are the same four spheres with a herringbone parquet wood texture (bottom panel). This texture is utilized
as a bump map in the shiny sphere at the far right of the lower panel. The spheres in the lower panel are shown with the
highest level of advanced lighting with real time shadows and ambient occlusion turned on.
163Lighting in Virtual Environments
FIGURE 8.4 Screen shots from OpenSim. The top image shows the Avatar/Preferences/Graphics tab menu, and the bot-
tom image shows the World/Environmental Editor/Environmental Settings menu. Both of these menus are crucial to creat-
ing lighting, shadow, and color temperature effects in your virtual environments.
164 Virtual World Design
8.7 THE IMPORTANCE OF SHADOWS
Understanding shadows and their importance is crucial to lighting design. Shadows tell us what the shape
and volume of an object are by the gradation of light to dark along the object’s surface; shadows tell us where
the location of an object is by their angle and shape on the surrounding surfaces and ground plane, and they
reveal the detail of a surface texture when we are close to an object. Shadows also support the emotional
dimension of a scene; they help to convey the message and mood just as powerfully as the light does.
How do we see shadows from lights in a virtual environment? Simply put, in a computer rendering a
real-time display of geometry with lighting on it, the most common way real-time shadows are created is
from a “shadow map” and the application of that map to the scene [3]. Much more is happening of course;
your computer is making several calculations, creating a depth buffer, and comparing the locations between
lights and objects. Control over the look of shadows, whether real-time or baked into the textures, is available
in varying degrees to the lighting designer of a virtual world. Each person visiting your virtual environment
may have the menu to activate the real-time shadows for his or her screen viewer, but some may choose not to
because his or her computer’s graphics system lacks the capacity to display them. This creates a need for you
as the designer to make the important decision regarding how your project will show shadows. Willall the
shadows be baked in, or will you rely on people to come by with their real-time shadow shaders on? Which
approach supports the look of your design in the strongest way? Sometimes, the best approach is a hybrid
shadow plan. Use baked shadow textures on architectural details and let visitors know to augment the scene
themselves by putting on the advanced lighting system if there is the capacity to view it.
8.7.1 amBienT oCClusion
As described in Chapter 6, another sort of “shadow” effect that can occur within your scene is called ambient
occlusion. This type of shading adds the effect of soft shadows and shades of gray in areas that are occluded
or blocked from a source of global illumination. Imagine what your street looks like at noon on an overcast
day. None of the shadows are hard edged or dark; they are soft and blurred and directly under most over-
hanging objects rather than being cast out onto the street surface. This kind of shadowing is not created by
calculating from a single light source; it is created by calculating from an area light that spreads through the
scene. Soft shadows appear where spaces are blocked by objects, such as the area behind the pillows on a
couch or the oor under a sofa. Ambient occlusion is a favorite rendering effect for 3D model makers because
it adds depth to the surface of a model and can be baked into textures [4].
In Figure6.22 (top panel), you see an image of a virtual warehouse while it was being built in Blender.
You can clearly see the textures showing its ambient occlusion shadows and shading. This effect can also
be added in real time to your scenes in Second Life and OpenSim through the Firestorm Viewer Graphic
Preferences menu. Currently, ambient occlusion is a graphics-processing intensive or “expensive” method for
creating shading and can cause “lag” in the frame rate of the image unless you have a superfast computer
and online connection.
8.8 HELP YOUR DESIGN LOOK GREAT IN ALL SORTS OF LIGHTING
With every generation of graphic processing cards, the world of 3D graphics shown to you in video games
and virtual worlds includes more lighting and shadow effects that are rendered in real time. Viewer settings,
computer graphics card capacity, Internet bandwidth, complexity of the geometry in the scene—all affect the
actual frame rate that the observer or game player will experience in an online world.
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