OLIVE: 3-D

UMCPOLIVE


Background

3D world visualization is a term used to describe viewing real world objects such as the human body, buildings, or molecules for the purpose of extracting information. This form of visualization should be applied when viewing the object in 3D or rather what is inside the object is key to the desired users' task. While designing visualizing and navigating tools for 3D objects is a difficult task, there is a high demand for it. For example, the National Library of Medicine developed the Visible Human Project. As a result, there are a number of software packages which render virtual flythroughs of the human body.

Volume visualization is, by far, the most widely used form of 3D World Visualization. This involves rendering real world 3D objects into some form of computerized 3D representation, whether it be projected on the 2 dimensional computer screen or viewed through immersive virtual reality equipment. Scientific Visualization is presently the primary use of volume visualization. Here, physical objects modeled in 3D may be studied and examined by the user in greater detail and may even be manipulated in order to, for example, test scientific hypotheses, simulate an event or process, or to practice a procedure. Current applications of this type include medical imaging, surgical teaching and planning, and weather modeling. Arie Kaufman has an excellent tutorial on volume visualization in his article, Introduction to Volume Visualization, referred to later in the Citations section.

Uses of virtual reality and VRML (Virtual Reality Modeling Language), in applications outside those mentioned in volume visualization previously, abound and are becoming even more popular every day. Architects and interior designers, for instance, are looking into using VRML to make virtual walkthroughs of proposed sites available to their clientele on the web. In education, children can now visit and walkthrough museums, international historic sites (e.g. the Pyramids of Egypt), other planets, etc. without leaving their homes or schools via the Web.

In further investigating this idea of the 3D world, a few branches were unveiled. The first one is the concept of "real" 3D objects like those in scientific, volume, medical, and even architectural visualization. Molecules, the human body and the interior of a building share complex relationships with other items. These are all objects that people may want to view the inner structures of before really physically "entering". For this reason, 3D visualization has proven to be key in understanding the inner or unexplored parts of objects the datasets represent. 3D visualization brings home the idea of containment, where the user is able to navigate up, down, forward or backward once immersed into the given environment.

The second branch in the 3D world is one that we classify as "artificial" or "synthetic" worlds or workspace. These are computer-enhanced worlds that have the look and feel of a real 3D world, but do not truly exist in the real world. Take Bookhouse for example. The user is able to navigate through a virtual reality 'library' and choose books and different stories to read. While this does involve a walkthrough of a 3D world, it is not the concept of needing to explore inside it that is key in understanding the dataset that is before the user but making a choice from a collection of books to read.

And yet another category in 3D World visualization, though questionable, includes objects that we can apply our intuition of real 3D objects to make them seem 3 dimensional. For example, trees, networks, GIS systems, multi-dimensional and temporal objects can all be modeled in 3D, but does it also follow that these objects are now part of the 3D world? WebBook and Web Forager out of Xerox Parc do great jobs of increasing the user's capacity for understanding information on the World Wide Web by incorporating 3D interfaces. These products, however, though they could be labeled '3D', would be better characterized in the 1D and Workspace sections, respectively, or even in the general class of information or data visualization, because of the type of information they are used to display.

The forth and last branch that we considered for the purpose of our research could readily be discounted without much deliberation. We considered objects such as 3D bar and/or pie charts, where data may be effectively visualized in 2 dimensions, to be forced 3D objects. If you have a bar chart that is rendered in 3D instead of 2D, has the data changed? The answer is an emphatic, "No!". The data is still 2D and thus should not be included when speaking about 3D visualization. Although 3D renderings of bar charts or pie charts may be appealing to some, empirical evidence suggests it makes the data more difficult to comprehend. In other words, what the presenter has created is "chart junk" as coined by Edward Tufte. According to Tufte, one dimension is being wasted when this "overcoding" is applied. For this reason, the projects and products listed on this page are intended for the purpose of making appropriate matches of 3D data and 3D representation.

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Last modified: Fri Jan 2 13:05:50 EST 1998 - {sgittens,tcombs}@cs.umd.edu