Glossary - Virtual World Design - page 348

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 irst 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,
or Imprudence. 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 ininite 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, deining 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 Wii 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 ield. The effects of these lights can only be seen when the
Advanced Lighting module is activated in the Avatar/Preferences/Graphics menu.