CSC 890 Advanced Computer Graphics (Web3D System Design and Development) Ilmi Yoon Monday 4:10 - 6:45

Survey on your CG related background §Basic Concept (Transformation, Camera, Projection, Rendering, Shading) §Software Tools (3D Studio Max, Maya, Alias, Director, VRML) §Library (OpenGL, Open Inventor, Renderman, directX, Java3D) §Advanced Issues (Animation, Rendering Acceleration, Geometry Compression, Global Illumination, Simulation, IBR…)

Basic Rendering Pipeline Data Base of 3D Models Visibilit y Culling Shadin g Transfor mation Projectio n Clipping & Display image  1V1V 1R1R N L  

Computer Graphics Area §Business models: Entertainment, Game, Education, Scientific Research, Medical, Industry, Web3D §Technical Categories l Rendering enhancement (Algorithm, hardware) l Simulation and rendering (natural phenomena, facial expression, hair, wrinkle, clothes, etc.) l 3D model acquisition l Volume/Isosurface rendering l Motion capture l...

Web3D §What is Web3D? l Interactive 3D graphics over WWW/Internet l Why is it different from traditional CG? l What is the future of Web3D? l What is the current business models of Web3D? E-commerce site (Viewpoint, Shout3D, Shockwave …) 3D cyber space (Blakxxon, ActiveWorld …) l Technical challenges of Web3D Bandwidth (geometry + texture) Real time rendering User Interface Design Compatibility

VRML( Virtual Reality Modeling Language ) §Online resource: §VRML is simply a 3D interchange format. l It defines most of the commonly used semantics found in today's 3D applications such as hierarchical transformations, light sources, viewpoints, geometry, animation, fog, material properties, and texture mapping. One of the primary goals in designing VRML was to ensure that it at least succeeded as an effective 3D file interchange format. §VRML is a 3D analog to HTML. l This means that VRML serves as a simple, multiplatform language for publishing 3D Web pages. This is motivated by the fact that some information is best experienced three dimensionally, such as games, engineering and scientific visualizations, educational experiences, and architecture. Typically these types of projects require intensive interaction, animation, and user participation and exploration beyond what is capable with a page-, text-, or image-based format (i.e., HTML).

VRML §VRML provides the technology that integrates three dimensions, two dimensions, text, and multimedia into a coherent model. l When these media types are combined with scripting languages and Internet capabilities, an entirely new genre of interactive applications are possible. §VRML is the foundation for cyberspace and the on-line virtual communities l VRML does not yet define the networking and database protocols necessary for true multiuser simu-lations

VRML §File format + ftp + rendering on the client side (plug-in) §VRML is based on the Open Inventor file format l does not define an application programmer interface (API). §Base of MPEG 4 ( & Java3D)

History of VRML & Web3D §In 1992 the Iris Inventor 3D toolkit was released as the first product of these efforts. Iris Inventor was a C++ toolkit that defined many of the semantics found in VRML today §In 1994 Mark Pesce and Tony Parisi built an early prototype of a 3D browser for the WWW ( created the VRML mailing list, www-vrml, and issued a call for proposals for a formal specification for 3D on the WWW) §VRML 1.0 was missing key features (animation, interaction, and behavior) §At its July 1996 meeting in Kyoto, the International Standards Organization's (ISO) JTC1/SC24 committee agreed to publish the August 1996 version of VRML 2.0

VRML + etc §VRML files may contain references to files in many other standard formats. JPEG, PNG, GIF, and MPEG files may be used as texture maps on objects. WAV and MIDI files may be used to specify sound that is emitted in the world. Files containing Java or JavaScript code may be referenced and used to implement programmed behavior for the objects in your worlds. Each of these is an independent standard, chosen to be used with VRML because of its widespread use on the Internet.

VRML + HTML + Java  VRML file inside an HTML file: This is a semistandard part of HTML using the or HTML tag, although HTML does not require that HTML browsers support embedding of VRML files (or any other type of file) into HTML documents.  Java code inside a VRML file: This is a standard (although not required) part of VRML 2.0, using a Script node that refers to the compiled Java code. §Java applet communicating with a VRML browser: This is a not-yet-standard extension to VRML 2.0 known as the External Authoring Interface (EAI). At some time in the future it will probably become a standard (but perhaps not required) part of VRML.

 Java classes corresponding to VRML nodes : Several companies are developing programming toolkits that define in- memory representations of VRML nodes that can be used in any way the programmer wishes. These can be extremely useful when implementing VRML browsers or VRML tools, but none are yet a standard part of either VRML or Java.  HTML file inside a VRML file : Using an HTML file as a texture map to display it inside a 3D world would be an interesting extension to VRML, but it is not yet supported by any VRML browser and is not part of VRML 2.0.  Java applet inside a VRML file : Using a Java applet as a texture map to display the Java program inside the 3D world would also be an interesting extension. Interaction with the Java program could also be supported by projecting pointing device motion onto the applet. However, this also is not supported and is not part of VRML 2.0.

An Overview of VRML §Scene Graph Structure VRML files describe 3D objects and worlds using a hierarchical scene graph. Entities in the scene graph are called nodes. VRML 2.0 defines 54 different node types, including geometry primitives, appearance properties, sound and sound properties, and various types of grouping nodes. Nodes store their data in fields, and VRML 2.0 defines 20 different types of fields that can be used to store everything from a single number (the SFFloat field type) to an array of 3D rotations (the MFRotation field type). §Event Architecture VRML 2.0 defines an event or message-passing mechanism by which nodes in the scene graph can communicate with each other. Each node type defines the names and types of events that instances of that type may generate or receive, and ROUTE statements define event paths between event generators and receivers. §Sensors are the basic user interaction and animation primitives of VRML. The TimeSensor node generates events as time passes and is the basis for all animated behaviors. Other sensors are the basis for all user interaction, generating events as the viewer moves through the world or when the user interacts with some input device. Sensors only generate events; they must be combined with other nodes via ROUTE statements to have any visible effect on the scene.

§Script nodes can be inserted between event generators (typically sensor nodes) and event receivers. Scripts allow the world creator to define arbitrary behaviors, defined in any supported scripting language. The VRML 2.0 specification defines Script node bindings for the Java and JavaScript languages. §Interpolator nodes are essentially built-in scripts that perform simple animation calculations. They are usually combined with a TimeSensor and some node in the scene graph to make objects move. §Prototyping: Encapsulation and Reuse VRML 2.0 includes a prototyping mechanism for encapsulating and reusing a scene graph (the PROTO statement). Geometry, properties, and animations or behaviors can be encapsulated, either separately or together. Prototyping allows the definition of a new node type in terms of a combination of existing node types, which can make VRML easier to use and can reduce the size of VRML files. §Distributed Scenes VRML 2.0 includes two primitives that allow a single VRML world definition to span the WWW. The Inline node allows the inclusion of another VRML file stored anywhere on the Web and the EXTERNPROTO statement allows new node definitions to be fetched from anywhere on the WWW. More generally, EXTERNPROTO allows nodes to be defined external to the VRML file and it is the basic extensibility mechanism for VRML.

For your inspiration…. §Electronic theater Siggraph ‘2001….