1 Using Voxelization and Ray-Tracing to Identify Wall Thinness of ...

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$Henry T. Schatz Math or Science Education Fellowship Application$

The advantage of using XML-based X3D is how easy it is to integrate the 3D model intoa Web Services-based system. For instance, any company that is familiar with XML will be ableto parse X3D easily. This also makes it relatively easy to convert X3D into other file formats asneeded. Since it is not a language, but an API, X3D leaves it entirely up to the browser to decidehow to implement the specification. In other words, one 3D browser might allow X3D-viewablecontent by implementing functionality with the OpenGL graphics language. Another browsermight choose to use DirectX to make the low-level calls instead. This allows vendors to optimizedifferent X3D browsers according to their user‟s needs.Another interesting aspect of X3D might be described as its modularity. The Web3DConsortium refers to this as the ability to be “componentized” [3]. What this means is that theAPI itself is segmented into modular blocks of functionality. Browsers can then choose tosupport one component of the X3D API and not another. This means developers and consumersof X3D content can select or build an X3D browser that is perfectly suited to their needs. Forinstance, engineers using X3D for modeling a pipe system would most likely want differentcapabilities from their 3D browser than would an educator. If a group never uses a particular partof the X3D specification, then it might benefit them to find a more lightweight browser that doesnot support that part of the specification. Given that X3D is often meant for viewing 3D contenton the web, providing a way to streamline a browser via the profile level is very beneficial. Anexample of profile level is shown in the file below.10Figure 6: X3D file containing a sphere as a high-level abstractionThe previous figure shows an example of a short X3D file. The very first lines of the filespecify which version of X3D is used. Together with the profile level, the specification numbergives the 3D browser a chance to recognize if it is able to support this file. Due to the sheer sizeand scope of the specification, not all browsers provide complete support for each and everyprofile level. As with most technologies, X3D continues to evolve and so the specificationcontinues to grow as well. However, unlike some other technologies, X3D is not rapidly
changing. Stability and longevity are key; one might describe X3D as a conservative, non-hastylanguage. In an effort to avoid deprecation of feature sets, the Web3D Consortium make it a goalto minimize language bloat and are slow to introduce a rash of new functionality. This givesemerging 3D concepts a chance to sort themselves out before they are absorbed into the nextX3D iteration.The specification, being an ISO-ratified standard, is very well documented. The actualX3D itself is also easy to parse: The format of is highlyrecognizable to those familiar with XML encoding. The data itself is nothing more complicatedthan tags and strings, as demonstrated in figure 4. X3D gives us the ability to describe geometryat a very high level of abstraction (should we so desire). For instance, to describe spheregeometry, one need only write: . The standard unit of measure inthe specification is the meter, so this would describe a sphere with a radius of 2 meters. Just asone would expect, when viewed in a browser one would see a round sphere (though one couldn'tnecessarily determine the sphere's size without seeing its size relative to another object in the 3Dscene).The following figure shows another X3D file, which would produce nearly identicalresults when viewed in the same browser: a round sphere would appear on the screen. Note theradical difference in the two files, however, and realize that the image below has been truncatedto save space:11
Page 2 and 3: 2Table of Contents1. Introduction2.
Page 4: for printing. This technique can be
Page 8 and 9: y the curve and the exterior is unb
Page 12 and 13: 12Figure 7: X3D file containing a s
Page 14 and 15: and less 'boxy' the more polygons a
Page 16 and 17: 16Child 3 contains points where x i
Page 18 and 19: An algorithm that processes the inp
Page 20 and 21: The algorithm we used for the trian
Page 22 and 23: 22Figure 11: An odd number of inter
Page 24 and 25: 24Figure 13: Example of a model fai
Page 26 and 27: grid point is a zero dimensional ob
Page 28 and 29: 28Figure 15: A two-dimensional exam
Page 30 and 31: 7. ResultsFive values are calculate
Page 32 and 33: 32Figure 19: Many voxels are flagge
Page 34 and 35: 34Figure 21: Closeup of two columns
Page 36 and 37: 36Figure 24: Unshaded mesh geometry
Page 38 and 39: Table 2 Simple Sphere results with
Page 40 and 41: dimensions. Note that the current s
Page 42 and 43: 42Figure 28: Default visualization:
Page 44 and 45: At the original one millimeter reso
Page 46: Despite these successes, I predict

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