T-Splines and Matt Sederberg

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T-Splines and Matt Sederberg
CEO at age 24! What a great way to splash into the CG World! Matt Sederberg introduces a new and innovative company called T-Splines, LLC in Orem, Utah, nestled in a valley of the Rocky Mountains. Matt studied Economics at Brigham Young University and he spent his last two years of college participating in business school contests, picking the brains of entrepreneur mentors, and mixing with members of BYU’s award-winning animation department.

His goal was to go into business in new technology. That goal is now realized in Matt's company that produces cutting-edge technology. With the company T-Splines, the future of 3D modeling is here. Computer Science professor Tom Sederberg, Matt's father, is the one who laboriously perfected the T-splines’ formulas over two decades. This new formula revitalizes NURBS and brings new control to modeling. Complex as this sounds, the average modeler can use T-splines technology.

So how do you really get to be CEO at age 24? It may be a combination of hard work, independence, dreams, a vision, and the magic of a product that needs to be shared with the world. Matt says:

“My dad and I, we’ve always been quite close. He’s always had a very high standard of his academic research, but while I admired what he did and even was attracted to mathematics and computers, where his talents lay, I had an independent streak in me that resisted following in his career footsteps: I wanted to do my own thing.

“As I progressed through college and became fascinated with how the economy works and how businesses operate in a capitalist society, I was eager to begin to apply all my book learning about supply and demand curves from economics, and actually get behind the controls of a business myself. I never would have guessed that my chance to start and run a business would come so soon — before I even got my diploma.

“In 2003, Kyle Welch, a lead from BYU’s highly-regarded Entrepreneurship program stumbled across some projects my dad was incubating in his research lab, and convinced him to enter some of these inventions into the school’s prestigious Business Plan Competition. Kyle contacted me, and while the two of us fine-tuned a commercialization plan for T-Splines, I also got a generous amount of mentoring of how to run a business from BYU’s resident entrepreneurs, and local industry folks, who were intrigued by the T-Splines idea. We ended up taking second place in this competition and earning $17,500 in cash and in-kind services—enough that my dad and I decided to go ahead and incorporate the business in late 2004.

“The most rewarding aspect of my job has been being able to help my dad commercialize the culminating invention of his years of research. We both view it as fortunate timing that his discovery and my coming of age aligned so well. It has also been rewarding for me to be able to make my own unique contribution to our company: while my dad and our researchers continue to develop new applications of the T-Spline technology, I have been able to head up the business development, which is where my own interests chiefly lie. Finally, my dad and I have enjoyed being able to create jobs and establish a company culture that reflects the values that we both share: hiring the smartest minds available, working extremely hard, and being supportive of the family responsibilities of our employees.”


Now, who and what are T-splines? The company T-Splines has developed a new way to manipulate NURBS control points and the resultant mesh. The technology T-splines are a superset of NURBS, which contain all the data that a NURBS model contains and more … and less. T-splines technology is a tool for artists to model in ways that were not mathematically possible before. The buzz phrase is "local refinement of surfaces."

NURBS stands for Non-Uniform Rational Basic Spline (pioneered by French engineers Monsieur Pierre Bezier of Renault, and Monsieur Paul de Casteljau of Peugeut). In short, T-splines technology is a method of simplifying and reducing the number of control points in a NURBS model, as well as adding control points where needed, while adding to the high detail necessary for complex shapes. T-splines, is also a subdivision tool. T-splines, is not just a polygon reduction tool, even though it has the ability to reduce polygon count. With T-splines, less data equals faster modeling, easier editing, faster rendering and reduced file size. Simply put, T-splines, is a revolutionary new way of organizing precision control points.



Partially funded by the National Science Foundation, Dr. Tom Sederberg also created a new "surface intersector algorithm based on T-splines." This means that there are a few new tools that the NURBS modeler can use to produce more organic shapes, more precise shapes, and do it all with far fewer control points.

In Dr. Sederberg's paper, “T-spline Simplification and Local Refinement," he states, "A serious weakness with NURS modeling is that NURBS control points must lie topologically in a rectangular grid. This means that typically, a large number of NURBS control points serve no purpose other than to satisfy topological constraints. They carry no significant geometric information. … T-splines are generalizations of NURBS surfaces that are capable of significantly reducing the number of superfluous control points from the NURBS model. The main differences between a T-mesh (i.e., a T-spline control mesh) and a NURBS control mesh is that T-splines allow a row of control points to terminate. The final control point in a partial row is called a T-junction."



Perhaps the easiest practical way to understand the difference between T-splines vs. NURBS, is the visualization of curves vs. flat polygonal mesh. In a flat mesh, to make a curve, one has to place a great many control points along the path that the curve is to be formed on. A sphere, for example, would require an infinite number of points to result in a spherical looking object. Infinite simply is not possible. Therefore, a finite number of points to make a sphere look like a sphere results in a high polygon count and at render time, still shows the flat surfaces and a rough looking model. Obviously, the lower the count, the rougher the resultant model appears when rendered.

Render engines are capable of additional smoothing according to the data in the model. Thus a NURBS model which has the ability to generate curvature information between two points (no longer flat mesh) is able to create a sphere with far less points than is necessary in a flat polygon model. Unfortunately, the curvature information in NURBS is limited to averaging the curve between points.

Some technology allows for cages to be built and curvatures defined by the cage. While this does result in a smooth sphere it still takes a substantial number of points to define what that sphere is to look like. In more complex models such as a human face, the number of control points necessary for compound curves increases dramatically. Thus, T-spline technology has the next level of curve interpretation.

The algorithms in T-splines formulate by Dr. Sederberg are such that a curve can be interpreted outside of the average between control points, or outside of the average in a cage. Curves can be interpreted in weighted and more organic forms, and as such, require even fewer control points to produce the same and modified smooth flow of a NURBS model.

T-Splines will be particularly powerful for CAD applications because, unlike NURBS, T-Splines can represent an entire CAD model without any gaps. This capability is likewise valuable in animation with applications like Maya. For example, a NURBS model that is stitched together with various NURBS patches, such as one patch of neck with upper torso, and another that does the head and face, is subject to stitch separation in extreme movement positions in animation. Not so with T-splines. A NURBS model converted to a T-splines model will not break apart at the stitch locations. The addition of control points does not change the surface. Additionally, the reduction in control points makes the model faster to manipulate and animate. Thus, the ability to add where needed, and reduce where not needed, is of great value to modeling efficiency.



Another advantage of T-splines is to revitalize the older NURBS models. Many modelers have scrapped their old models because they were made in older NURBS programs, and the time to upgrade the model is longer than it might be to just build the model from scratch in modern software. By way of example, the Zygote Media Group has made their 10-year-old male and female models available as free downloads on the T-Splines website. These downloads are the T-spline converted versions so that modelers can explore and compare the differences.



This is where T-Splines shines for companies like Zygote that want to resurrect older models with minimal time expenditures. An older model that might have a huge file count, or has stitching failures, or that simply needs some detail updates in facial features — when converted to a T-splines model — is once again useable at modern technology levels. You never know, we may one day see the Dork back in action again.



The future of T-Splines is a wide-open field just waiting to be developed. One of the focuses on the future is meeting the needs of organic NURBS modelers. Certainly the gaming industry will look long and hard at this Maya plug-in as a way to bring greater detail over limited bandwidth. T-Splines plans to continue with aggressive updates, and is currently only available for Maya.

T-Splines can be purchased through the T-Splines store.
It requires Maya and will not work with Maya PLE .
  • T-Splines Full Version (with CD): $799.00 [USD]
  • Downloadable Version (without CD): 791.00 [USD]
  • Academic Version: $199.00 [USD]
  • Learning Edition (save disabled) is available for free.
    Tech Views
    is a regular featured column
    with Renderosity Staff Writer/Sr. Tech Editor
    Eric Post [EricofSD].

    December 27, 2005

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    Member Opinions:
    By: Paula Sanders on 12/26/05
    Extremely interesting. Thanks for the product review and the insight into Matt Sederberg.

    By: nemirc on 12/26/05
    I am not very fond of NURBS due to workflow issues and pretty much because they are very complex to use. I may give this one a try in the near future.

    By: electranaut on 12/27/05
    I'm very interested in the idea since I use NURBS almost exclusively and I can see the advantages. I'd really like to see some standalone package using this technology, though, since having to own Maya is a pretty serious limitation.

    By: jpiazzo on 12/28/05
    What is the difference between this spline method compared to Hash AM's?

    By: REALVISION101 on 12/28/05
    Yes,that's what I was waiting for!
    Thanks for inovation Matt :)

    By: EricofSD on 12/30/05
    jpiazzo, I passed your question on to Dr. Tom Sederberg. From what I know, AM is a very fine application that gives the artist the ability to create some fantastic cartoon type characters and animate them. “Alien Song” is one of my absolute favorites.

    Nevertheless, there are differences in the technology. Dr. Sederberg said, “T-Splines are compatible with NURBS. This means that every NURBS can be converted without error into a T-Spline and every T-Spline can be converted without error into a NURBS.” So the question you have to think about is whether or not AM fits in with NURBS technology or if it uses a proprietary technology, like patch modeling. This comes into play when exporting for use in other applications. And the second question is if that matters to you. Maybe it does, maybe not.

    Without being terribly familiar with AM myself, I would say that the big advantage of T-Splines in the context of AM is that it does very well with organic shapes except that it does so in MAYA which has some exceptionally high end modeling tools. As such, I would suspect that a modeler can do more with MAYA tools and T-Spline technology.

    Another advantage is the export features which allow for a T-Splines mesh to fit into a great workflow with other applications.

    Also, the ability to make an entire model such as a humanoid in a single mesh is quite remarkable. I don’t know if AM can do that or if it needs to put pieces together and stitch them in some way. Of course, the detail in the mesh is virtually unlimited with T-Splines, meaning that the mesh can be exceptionally complex if the artist wanted. Even if it is not exceptionally complex, it will have a fantastic detail about it as compared to other modeling technologies.

    By: EricofSD on 12/30/05
    jpiazzo, part 2


    There are many comparison questions that arise when we think about different modeling engines. Dr. Sederberg said, “If I were to identify the most important of these differences, it would be the compatibility issue. There are a lot of different mathematical formulae for surfaces that researchers have published, but few of them ever become productized because they are not compatible with existing commercial technology. One reason we believe T-Splines is likely to gain widespread adoption is that T-Splines is compatible with the rest of the modeling world.”

    If I had to guess more into your question, I would guess that what you really are asking is if you can do more cool stuff with T-Splines than you can with AM. My gut answer is yes and no. Yes because the tools and organic curves that T-Splines offers in conjunction with MAYA are tops. Lets face it, MAYA is king of the apps right now in the movie theatre. Its also up there on price and learning curve. AM does cool stuff too and its affordable. If the detail and quality of AM is acceptable to you, then great. If you are looking into other apps then MAYA and T-Splines should definitely be on your research list.

    By: EricofSD on 12/30/05
    Hehehe, here's what Dr. Sederberg sent, jpiazzo, so best wishes to you.

    ............

    Response by Tom Finnigan and Tom Sederberg on 2005-12-30:

    From an artist's point of view, there are two important differences between T-Splines and Animation Master's Hooks and Hash Patches.

    First, Hash Patches are not compatible with other programs. This means if you want to create a model in AM and export it to a different program for UV mapping or animation, you are out of luck. Likewise, you can't create a model in some other program using NURBS or SUBDs and import them into AM. T-Splines are completely compatible with NURBS or SUBDs. You can import a NURBS or SUBD model into T-Splines without error, and you can export a T-Splines model into NURBS or SUBDs without error. We read about a Third-Party program that will export Hash Patches into NURBS patches (actually, Bezier patches), but the resulting NURBS patches usually will have serious gaps between them.

    Second, T-Splines are built on a more advanced mathematical framework than Hash Patches. T-Splines are truly C2 (curvature) continuous, whereas Hash Patches are at best C1 (tangent) continuous. Also, some artists have told us that Hash Hooks do not always behave nicely.

    Disclaimer: We are not authorities on Animation Master. Our response is based on what we gleaned in an afternoon of studying the Hash.com and other websites that discuss Hash patches and Hooks. If we are misinformed, please correct us.

    By: Teyon on 12/30/05
    Pity it's Maya only. I was looking foward to jumping back into Rhino with this new technology. Character modeling with NURBS/T-Spline combos would be loads faster than building up with polys for me.

    By: deemarie on 12/31/05
    Outstanding interview/review Eric.

    A special "thank you" also to Matt and Dr. Tom Sederberg, as well as to Tom Finnigan, for their additional input.

    Dee-Marie

    By: sederberg on 1/2/06
    Response to Teyon:
    Look for a T-Splines plugin for Rhino in 2006.

    By: EricofSD on 1/2/06
    Dr. S, can we hope for a Softimage plugin too?


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