345
Glossary
Additive Color: a color mixing system for light, in which red, green and blue light will combine to create
white light.
Affordance: a term popularized by Donald Norman in 1988, which referred to the actual and perceived
qualities of an object or its design that implied to the observer how it could be used. For instance,
the affordance of a doorknob and its inherent usage is implied by its shape and position on a door.
Ambient Light: in 3D computer graphics, ambient lighting is represented by a widespread distribution of soft
light of one color over the objects of an entire scene. This effect is created with rendering settings on
the textures of 3D objects, as well as by the addition of diffuse sources of light into the scene.
Ambient Occlusion: a realtime lighting effect applied when the Advanced Lighting is selected in the
Firestorm viewer (Avatar/Preferences/Graphics/). This creates the effect of soft shadows and shades
of gray in areas that are occluded or blocked from the source of global illumination. This effect also
found in 3D modelers like 3DS Max and Blender, and used for creating additional lighting detail
in a scene.
Anechoic chamber: an echoless soundproof room used for audio testing.
API (Application Program Interface): is a system or group of programming directions, instructions or stan-
dards that allows the user of one program to access specic parts of the program or data from others,
or to ask one piece of software to perform services for another program.
Atmospheric perspective: the creation of a sense of perspective within a landscape by increasing color fade
and blurriness of background elements as they retreat in distance from the viewpoint.
Avatar: a 3D gure, sometimes human, and sometimes another species that represents a person, or an
articial intelligence program inside a virtual world. An avatar communicates and interacts with
the other people or their avatars.
“Baking” Lighting: creating special textures for objects in a 3D scene that have the highlights and shadows
rendered (baked) onto their surfaces, in addition to the colors and patterns inherent to the texture
itself. This approach to creating content adds the effect of lighting to a scene without the need for
any real time shadow rendering by the graphics card.
Binaural: hearing sound from two microphones, two channels, or two ears. This is how people with normal
hearing perceive the world. Comparison by the brain of the two signals tells us where the sound is
located and if it is moving.
COLLADA (.dae) le: a Digital Asset Exchange le format (.dae) used to exchange 3D content between
3Dmodeling programs and to upload those mesh models into virtual worlds and gaming engines.
Composition: arrangement of items in a 3D design to create a balanced image from all visible sides. This
includes lighting, sound, and the elements of Line, Space, Shape, Form, Color, and Texture.
Design for all: see Universal Design
Diegesis: to tell a story with the use of a spoken narrative, as opposed to Mimesis, which is telling a story
by visually acting it out.
Doppler Effect: this effect, also known as Doppler pitch shifting is the pitch shifting effect heard by a
listener as a sound emitter moves by quickly. The relative velocities of the emitter and listener are
compared and the resultant calculation used to change the pitch of the emitter’s sound.
First person camera: a point of view provided by a game or avatar’s camera that does not allow the person
playing to see themselves, but only the view as they would see it from their eye position, similar
346 Glossary
to “mouse look” in Second Life. Usually found in “rst person shooter” games and may allow the
players to see their hands and weapons for aiming purposes.
Frustum: the pyramidal shaped volume that a projector creates from the start of its beam until it hits a plane
or intersecting surface.
Gouraud shading: developed by Henri Gouraud, this kind of smooth shading uses the vertex normals (nor-
mal average of all surrounding planes) and the interpolation of many vertex intensities across the
surface of a 3D polygonal model to produce the effect of a smooth surface. This kind of shading
produces a smooth light-to-dark transition in the shadows of the geometrical surface.
Grieng: actions or activities by avatars with the intent of making the experience of a virtual place unpleas-
ant or threatening. Often involving push scripts, overloading the location with prims, or broadcast-
ing a loud noise via the voice chat channel.
Grid: a collection of regions laid out in a rectilinear grid system, interconnected via a simulator grid service
for transport of avatars, messages and content across the virtual landscape. Represented in a map
form for the players to orient themselves to the environment, a grid can include thousands of regions.
These regions can be grouped to form “Continents” or a “Main Land.”
Harmony of Dominant Tint: a method of unifying elements in a design or artistic composition by coloring
all of them with the same tint, which visually harmonizes the composition.
HMD: (Head Mounted Display): devices such as the Oculus Rift that project a stereoscopic image on a
display screen, or the Virtual Retinal Display that projects a virtual world image directly into the
eyes. These devices bring the visitor into a state of deeper immersion in a virtual world.
HUD (Heads Up Display): a graphic element within the player’s visual eld that allows the player to access
menus, activate programs or scripts, or gives information for the purposes of enhancing the virtual
environmental experience.
Ideagora: a hybrid term that combines the words “idea” and “agora” (ancient Greek public space), and is used
to represent places on the Internet where people can meet in a virtual space to exchange ideas, and
build things together. Don Tapscott and Anthony D. Williams rst used this word in “Wikinomics:
How Mass Collaboration Changes Everything,” (ISBN 1591841380), December 2006.
IAR (Inventory ARchive): a le saving process which collects all the content assets of an avatar’s inventory
into one single le, allowing that data to be moved and loaded into another OpenSim installation or
transferred to another avatar’s inventory.
IEZA framework: a concept framework, created by Sander Huibers and Richard van Tol at the Utrecht
School of the Arts, for the purpose of organizing and dening the audio used in virtual environments.
Immersion: the shift in a player’s perception as their attention focuses on the virtual world and its activities.
This effect, enhanced with the use of headsets and/or viewers such as the Oculus Rift, utilizes sound
effects, music, and visual images to envelop the player in the experience of the game.
Inworld: pertaining to the virtual location of an object, sound, animation or avatar entity that is experienced
and/or manipulated through the client viewer while the user is logged into a virtual world.
Instantiation: the process of creating an object within a virtual space by accessing a prebuilt element, or
bringing in pre-built content. All content is an “instance” that represents the underlying data. This
process is also known as “rezzing,” or to “rez” an object. An object is rezzed by dragging it from the
avatar’s inventory list to the virtual ground, or building platform.
JIRA: bug tracking software for projects and programs created by Atlassian. The name is a truncated version
of Gojira, the Japanese name for Godzilla.
LSL (Linden Scripting Language): a language based on the Java and C programming languages and used
throughout Second Life and OpenSim virtual worlds to direct an object in that world to do a series
of tasks. LSL scripts are located in the contents of objects in the virtual world environment. An
347Glossary
avatar can wear these scripted objects, examples are scripted hair, scripted clothing, and scripted
interface tools. These scripts are interpreted and executed by the server running the virtual world
environment, and seen by the user through the client viewer when they are logged into a virtual
world.
Material: in the 3ds Max modeling system and in virtual worlds, a composite of the shader code and the
texture maps. It is used on the surface of a 3D object to create its unique look. In some cases,
“ material” is used interchangeably with “shader.” See also shaders and textures.
Mesh: a common term for the geometric forms made in modeling programs such as 3dsMax and imported
into a virtual environment.
Mimesis: to tell a story by acting it out, as opposed to Diegesis, which is to tell a story with vocal narrative.
MMORPG: an abbreviation for Massive Multiuser Online Role Playing Game, which in its simplest form
is a virtual environment that allows for a number of people to log in remotely and take the roles of
various characters in order to play the game.
NPC (Non-player character): a character in the virtual world who is not controlled by a person during the
game and may be interacting with the players by utilizing articial intelligence code.
OAR (Opensimulator ARchive): like the IAR, a le saving process that allows for the collection of all the
elements on a sim; the terrain, objects contained on it, the scripts, textures, and all parcel and region
data into one le for distribution and reconstitution of the build on another system.
OpenSim: also called Open Simulator, an open source computer based platform that creates a virtual world
or virtual environment. It is the 3D web, where instead of web pages, there are 3D regions linked
together through servers on the internet.
OSSL (OpenSim Scripting Language): an extension of the LSL or Linden Scripting Language used
in Second Life, also provides for extra functions that an Open Simulator based virtual world
understands.
PCM (Pulse-code modulation): the uncompressed audio format usually found with a .wav audio le, com-
monly used in virtual worlds.
Per Pixel Lighting: a technique used by the computer to render out lighting effects based on the illumination
calculation for each pixel in the scene. While this requires more graphics processing, it can be used
to create much more visual detail in the scene.
Per Vertex Lighting: a technique used by the computer to render out lighting effects by calculating the
illumination at the vertices of a 3D object in the scene, and interpolating the lighting across the
surface of its faces.
Phasing: a selective display of environmental qualities, objects, and non-player characters utilized in various
MMORPGs (Massive Multiplayer Online Role Play Games) to enhance the game, and keep the
environment changing for the players.
Point Light: a light source that emanates from one central point, such as a hanging light bulb would in a
dark room.
Poseball: a 3D object in a virtual world, often a sphere, that contains an LSL script and animations or poses.
This enables the avatar to take up positions, or poses on such things as furniture, and vehicles.
Prim (or primitive): a simple 3D shape created in a virtual world. Also called “objects” (when rezzed in
Second Life), these are used by the residents to build houses, roads, and other content that creates
the world. The basic collection includes cube, cylinder, sphere, torus, prism, ring and tube.
Quaternion rotation: one of the two methods of rotational representations used in LSL scripts to dene how
an object will rotate in space. Consists of x,y,z variables to represent the axes of rotation and the
svariable to represent the angle of rotation. The other method used is Euler rotation, which employs
yaw, pitch and roll as vectors.
348 Glossary
Real Time: the creation of a series of rendered images rapidly enough to produce the illusionary effect of
objects and avatars moving at the same pace as one would observe in the real world.
Region: the virtual land, mountains, islands, or possibly open water, in a virtual world. This land can come
in various sizes, but would typically be 256 meters by 256 meters in size if you were in Second
Life or Open Sim. Regions created in a mega region format are subdivided into parcels set with
individual permissions for visitor access, media playing, build rights and other qualities desired by
the region owner.
Rez: term used in Second Life, OpenSim to describe the process of creating an object in the world, either
by using the viewer’s Build Edit/Create menu to “rez an object” or by dragging content from the
avatar’s inventory onto the virtual ground so that it can be seen and manipulated by the avatar. From
the programmers term “resolve,” and rst used in the movie “Tron” Walt Disney Productions 1982.
Script: a set of instructions written in such program languages as LSL (Linden Scripting Language for
Second Life), UnityScript (for the Unity game engine), C#, (pronounced “C sharp”), and others too
numerous to mention. These scripts will activate and control the behavior of building elements,
objects, avatars and non-player characters.
SL (Second Life): a persistant virtual environment or world created by Linden Labs in 2003, and it is
accessed via the internet with free client viewer interfaces such as Firestorm, Second Life viewer,
orImprudence. Most of the content and design of the world is created by the residents, some of
whom make a business of building and selling digital goods. OpenSim is a direct spinoff of this
world, and the foundation of a new generation of 3D virtual worlds.
Shader: a set of computer instructions utilized to create shading, lighting, and special effect such as cartoon
looks on the objects in a scene. By using various algorithms to affect the overall look of the rendered
scene, they can create an almost innite range of effects. See also material and textures.
Shadow Map: a virtual shadow created in a 3D environment. A shadow map is made from the comparison of
a the light’s position (x,y,z coordinates in a scene) to the lit objects position in a scene. This compari-
son by the rendering engine creates a depth map (depth buffer) of the object from the light’s point of
view and saves it in the graphics memory. In this grayscale depth map, as the objects surfaces recede
from the location of the light, the black level increases, dening a “light space” for each light source.
When a point in the scene is rendered from the camera view for your display screen, two spatial
qualities are compared, 1) where that point is in the scene (world coordinate or x,y,z), and 2) where
it is in light space (the depth map information). By comparing these two sets of information through
various matrices, the rendering engine decides what is shaded and lit and creates a shadow map.
Simulation: also called sim, this is the virtual environment produced by the server when it is running a
virtual world program such as OpenSim or Second Life. The word “sim” is often used interchange-
ably with “region,” to signify one simulation area.
Sim-on-a-stick (SoaS): a portable version of an OpenSim virtual region distributed under Creative Commons,
that can be run off a USB stick since it contains a portable server program as well as the Wi admin
panel for avatar logins. This program was developed by Dr. Christa Lopes (Diva Canto in SL) and
is distributed from a site administered by Ener Hax at http://simonastick.com/.
Specular highlight: the highlight or “hotspot” on the surface of a shiny object that gives a clear indication
as to the color and position of the lights in a 3D scene.
Spotlight: a spotlight is created in Second Life and Open Sim by selecting the light function in the
Build/Edit/Features tab menu and applying to a prim. This kind of light source will have Field
of View qualities, as well as focusing capacity. It may also be called a projector light when it is
displaying a texture image with its light eld. The effects of these lights can only be seen when the
Advanced Lighting module is activated in the Avatar/Preferences/Graphics menu.
349Glossary
Texture: a 2D graphic image such as a photograph, or illustration that is applied to the surface of a 3D model
to create its unique qualities. For instance, a photo of bricks might be applied to a large box, to
create the illusion of a brick wall object.
Third person camera: the visual perspective on a scene in a virtual world that has the cameras point of view
behind and slightly above the avatar or character the camera is following. This point of view, which
can be partially controlled in some games and completely controlled in virtual worlds, allows for
the player to view surrounding areas, see the approach of other players, and to see their own avatar
as they direct it on a course through the environment.
Transform: the process of calculating the graphical information received from a moving point of view in a
3D scene and creating a 2D image from it. This process is happening when your avatar is walking
through a 3D environment, and you are viewing it on a computer screen.
Universal Design: a “universal” approach to making the design of an environment, virtual or real, accessible
to all people. This includes creating easy access to the space, redundancy of information in both
audio and visual formats, directions and information in more than one language and color palettes
that can be seen clearly by all. This is also known as “Design for All.”
UUID: also called a “Universally Unique Identier,” an alphanumeric code that identies each asset, instance
of the object, avatar and land parcel.
Vertex: on a 3D model, the point where the lines or edges of a surface start. Many 3D modeling programs
allow for the manipulation of these points in order to “sculpt” the form of the 3D model.
Virtual Reality: a computer generated 3D enviroment created for the purpose of enabling people to visit a
simulacrum of our real world or a completely imaginary world. This kind of reality is enhanced for
the player with large screens, stereoscopic displays, sounds played through a headset, and haptic
feedback to create a compelling immersive experience.
Visuospatial Sketchpad: a component of human memory that initially starts with collection of short-term
memories, and caches them into the working memory for recall later. This is a valuable tool for
designers since it provides them with a vast store of visual, spatial, color and movement information
that can be recalled at will.
Wireframe: a viewer mode that removes the surface rendering, and shows only the lines and vertices of the
3D model. In the Firestorm viewer, the wireframe mode can be accessed in the Developers menu,
which along with the Advanced menu, is activated on the top bar of the Firestorm interface after
the basic installation is done. The key commands are (Ctrl+Alt+D) and then (Ctrl+Alt+Q) to turn
on these hidden menus.
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