Animation is the simulation of movement created by displaying a series of related still images (called frames) in rapid sequence. Cartoons are a good example of animation, as are the crude hand-held ‘flip movies’ children like to make. As computational power and speed increase, simple 2-D animation is now giving way to more realistic 3-D animation.
Animation is not the same as video or film (although these motion formats can obviously display an animation). Whereas video and film takes continuous motion and break it up into discrete frames, animation starts with a series of separate still images and puts them together to form the illusion of motion.
You can create animation files using one of several methods. Simple 2-D animations appropriate for Web page display can use the animated GIF format, previously described. Alternatively, you can ‘string together’ a series of related still images as a video sequence using an open multimedia standard such as Microsoft’s AVI, Apple’s QuickTime or MPEG (see the separate discussion of multimedia formats). These animations are playable on both the desktop and within Web browsers via plug-ins. Also geared for Web page display via plug-in are Macromedia Flash (*.SWF) ‘movies.’ Alternatively, Web developers with programming skill can use Dynamic HTML (HTML + style sheets + Javascripting) to create Web animations that ‘play’ on Web pages without plug-ins.
Studio-quality 3-D animations are created by high-end (and expensive) software such as Autodesk’s 3-D Studio MAX, NewTek’s LightWave, and MetaCreation’s Ray Dream Studio. All these commercial products produce proprietary animation files.
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For a good tutorial on animation, especially as applied to the Web, visit:
http://hotwired.lycos.com/webmonkey/multimedia/tutorials/tutorial1.html |
Any look at an PC game will tell you that three-dimensional (3-D) graphics are becoming a popular way of portraying more realistic and interactive images on computers. In addition to gaming, 3-D graphics are ideally suited for architectural, educational, engineering and scientific/medical visualization applications. Typically these applications require intensive interaction, animation, and user participation and exploration beyond what can be provided by text or static 2-D images.
For example, 3-D graphics can provide orthopedic surgeons with a precise virtual reconstruction (from CT scans) of the hip bone and femur that can be visualized and 'manipulated' in preparation for artificial hip replacement surgery. Alternatively, a cardiac surgeon can obtain a 3-D visualization of the heart's coronary arteries in realistic three-dimensional space, and use this virtual model to precisely identify the location of obstructed vessels (also in preparation for surgery).
3-D graphics involves the generation and display of three-dimensional objects in a two-dimensional (2-D) space (e.g., the display screen). Whereas pixel location in a 2-D graphic is defined only on the X-Y axes, a 3-D pixel adds a third axis, called the depth property. Pixel depth indicates where the point lies on this imaginary third axis.
When many 3-D pixels are combined, each with its own depth value, the result is a 3-D surface, called a texture. In addition to textures, 3-D graphics also support multiple object interaction. For example, a solid foreground object can be made to partially hide or obscure any object behind it. 3-D graphics also incorporate techniques such as ray tracing to apply realistic shadows to images.
The process of converting information about 3-D objects into a 2-D bitmap for screen display is called rendering. 3-D rendering requires considerable RAM and fast computational processing. Until recently, only powerful workstations could render sophisticated 3-D graphics in real time. Today, inexpensive 3-D graphics accelerator provide real-time 3-D rendering (and thus realistic interactive gaming capability) on desktop personal computers.
3-D is also available on the World Wide Web, current using an open standard called VRML. VRML, pronounced 'vermal,' is an acronym for the Virtual Reality Modeling Language. VRML was formally approved by the International Organization for Standardization (ISO) in 1997.
VRML can be thought of as the 3-D analog to HTML, i.e., a relatively simple, multi-platform language for publishing 3-D images on the Web. Its 'tags' define most of the commonly used features found in 3-D applications, such as geometry, light sources, viewpoints, material properties, texture mapping, and animation.
Up until now, to display and manipulate a 3-D image based on the VRML standard on a Web page required the use of a 3-D capable browser. Typically, browser support for 3-D imaging is provided by plug-ins. A new standard, called eXtensible 3D (X3D), will eliminate the need for browser plug-ins. X3d is the next-generation 3-D graphics specification that incorporates and extends the capabilities of VRML 97. The name eXtensible 3D was chosen to indicate that this new standard is based on XML technology, thus providing 3-D functionality to any XML-capable browser.
© Craig L. Scanlan, 2001. Version 2.0 - January 2002. Original version January 2001.