Expand Your Vocabulary

avatar
a physical manifestation of the user at the current viewpoint in a world.

backface culling
specifies that polygons not facing the camera are not rendered (if you can't see the polygons, don't waste time rendering them). This is useful for solid objects.

billboard
an object that rotates around a specified axis so that it always faces the viewer. Billboards are a useful optimization technique.

browser
a software program that can view VRML worlds. Also called a viewer or a player.

clipping plane
clipping planes define the area in the scene visible to the camera. The near clipping plane is the point closest to the camera that is still visible; the far clipping plane is the point farthest from the camera that is still visible.

clone
a copy, or instance, of an object. A clone defines the selected object as a master for producing multiple instances. All instances share this master description identically, tracking all changes to its shape and appearance.

crease angle
the angle between the normals for two adjacent faces of a polygon.

dihedral angle
the angle between two adjacent polygons.

edge
where two faces (polygons) of a model meet. The term edge is different than the term line, in that it implies membership in the face.

event
an indication that something has happened. Outgoing events send their values to incoming events, which receive values. The connection between two events is called a route.
face
a single polygon, defined by points and lines; may also refer to a "perceived" face, which is a rendered "side" of an object that may be composed of several polygons. A group of faces make up a model's surface.

iconic objects
geometric placeholders for nodes which will be invisible to a VRML browser, for example, sound and light nodes.

IndexedFaceSet
a VRML node that defines the coordinates for a set of polygons that make a shape.

inline
a file referenced by URL (Uniform Resource Locator) within another file. In VRML files, inlines are downloaded separately from the main file and are a good way to speed up transmission and rendering of the main file. Some browsers display inlines as bounding boxes while they are loading.

keyframe
a pose at a particular time. The Keyframe Animator interpolates between poses, filling in values to move from one pose to the next. A keyframe can also contain values for viewpoints, textures, materials, and shapes. The Keyframe Animator interpolates between the values to transition from one viewpoint, texture, material, or shape to the next.

line
defined by two points (vertices) of a model; also see edge.

LOD (Level of Detail)
an object which appears to change to display the appropriate level of detail depending on viewing distance. LODs are, in fact, multiple representations of the same object.
For example, if you are looking at a forest from far away, you don't need to see the individual trees. The LOD might be made of large polygons that represent a forest. As you get closer, the LOD is replaced by another LOD made with more polygons so that you can see tree trunks and leaves.

mapping
instruction for placement of packaged files.

member
an object within an animation that moves as a unit in the scene.

normal vector (or normal)
a directional line that is perpendicular to a surface. A normal indicates the front of a face.

object
a single 3D item in a VRML scene, or an item that is part of a grouped object's hierarchy.

orthographic projection

2D view of objects in a scene; typical orthographic views are top, front, and side.

package
to locate all the files necessary to create a document or world and organize them for publication on a Web server.
PEP
Points, Edges, Polygons. Refers to Cosmo Worlds's interface to the VRML node IndexedFaceSet.

PEP Editor
the mode used to model PEP objects (PEP modeling). The PEP Editor is indicated by an orange frame around the object you are editing.

PEP object
an object which has been converted to its individual points, edges, and polygons.

PEP modeling
editing an object's points, edges, and polygons; edits the coordinates inside the IndexedFaceSet node.

perspective projection
3D view of objects in a scene.

point
a single vertex in a model.

polygon
in Cosmo Worlds, a face of a model, defined by the model's points and edges.

proxy
an object to be used for collision detection in place of actual geometry, which is usually more complex than the proxy.

publish
to copy a set of packaged files to a Web server where they can be accessed by Web clients.

root
a top-level document or world in the packaging directory. All files referenced in this document, as well as the local files referenced by those files, will be included as part of the package.

route
connection between two events.

surface
a set of faces; the surface of a cube includes all of its faces.

VAG (VRML Architecture Group)
a group of technical experts formed to set standards for creating and displaying 3D worlds on the Web. See the VAG home page for additional information.

VRBS (Virtual Reality Behavior System)
a VRML behavior scripting system prototype developed by the San Diego Supercomputer Center (SDSC). See the VRML Behaviors home page at the SDSC for more information.

VRML (Virtual Reality Modeling Language)

VRML is a standard way to specify 3D objects for viewing across the World Wide Web.

VrmlScript
a programming language, similar to JavaScript, that is used for scripts contained in a Script node. Click here for the complete VrmlScript specification.