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always under construction 


I was born in the Netherlands and educated in Switzerland and Canada. I can call myself a doctor. As a result I speak and write in Dutch, French and English. I also write computer code, think mathematically and dream in images.

For a living I do something called research. This involves many activities. Reading papers and books. Interacting with fellow researchers usually in front of  a white board. Attending and presenting at conferences all over the world. Surfing the internet. Basically thinking and experimenting by writing up ideas and coding them. This is an iterative process. Now and then the resulting code has to be useful to my employer du jour and our customers to pay the bills. Research also provides intellectual satisfaction, a life time achievement award and geek Oscars.

The motivation behind my research comes both from practical problems and pure intellectual curiosity. A practical problem can have a novel theoretical solution. Conversely "pie in the sky" research can lead to practical applications. Research is multi-faceted. Research is also cosmopolitan. I have done research in Geneva, Toronto, Paris, Helsinki, Seattle and when on travel in places like Mexico and New Zealand.

I now live in an old Victorian house in Toronto's funky Cabbage Town with my wife Pam, daughter Gillian and dog.

In my research I like to combine Art, Mathematics, Science, Computers and other cool exotica.


Simulacra Et Motus



Capturing Nature's beauty fascinates both artists and scientists. Their tools are paints, brushes, numbers, laws, differential equations, chisels and so forth; and the computer!  I am interested in developing models and codes that simulate and depict natural phenomena. Examples are clouds, fire, water, oceans and trees. This research finds applications in the movie industry, game engines, virtual reality, visualization and Art. Just to name a few. In this research we are free to play God and invent new models and depictions of Nature beyond physics. This is what makes this research such a fascinating field of inquiry. Our motto is "if it looks good it is good."



Surfaces naturally describe most shapes in our world. Mathematical models play an important role in precisely describing surfaces. These models are then fed to a computer to generate digital representations of shapes. The output is either kept in the virtual (movies/games) or constructed in the real (fabrication). There is a whole zoo of computer surfaces: point clouds, meshes, splines, NURBS, implicits, subdivision surfaces (subds), etc. I have played with many of these creatures but I am most fond of subds, which are obtained by a sequence of refinement steps of a coarse mesh. To illustrate. Imagine starting with a cube. Through an infinite process of corner cutting one obtains a smooth sphere-like surface in the limit. It turns out that this process also admits an exact mathematical form.



The Art of Rendering is to depict a given representation of a virtual world that we can see. The virtual world exists as bits in the computer while the visual experience is stimulated through our senses. Usually research follows the graphics pipeline: start with a model of a three-dimensional world including light sources, then project. This usually results in an image. If the world is dynamic then so are the images. Research in Rendering involves many different components: reflection and refraction models, global interaction of light, sampling, perception just to name a few. I have done research in some of these areas. Most notably in the area of local surface illumination models: diffraction and skin.



Fluids are cool and they are everywhere. Think of tears, honey, hot showers, waterfalls, mud, lava and so on and so on… and fire and air and rocks. What? The last three ones surely aren’t fluids you might think of. But they are fluids as well and that is the beauty of the study of fluids. A fluid is anything really that changes its shape over time in a seamless manner. Even cooler is that their slick meandering over time can be described using fancy mathematics. This is where Art meets Science. Leonardo da Vinci, the great Renaissance man, embodies this spirit perfectly with his famous paintings and his legendary scientific notes. How cool would it be to recreate these beautiful looking fluids on a computer screen?



The world is made of interacting shapes. Motion and time emerge from these interactions. The basic idea behind Nucleus is to generate interesting and complex behaviors from simple building blocks. Nucleus is particle based and treats interactions as constraints including deformations and collisions. Shapes are modeled as simplicial complexes, a generalization of triangular meshes to arbitrary topological dimensions. Points, edges, triangles, tetrahedra and their assemblies are all treated in the same framework. The motion of the particles under constraints is solved using a symplectic integrator. In other words Nucleus tries to resolve for displacements that satisfy the constraints first followed by an instantaneous update of the positions of the particles. Nucleus has been used in Hollywood blockbusters to model rigids, cloth, chains and hair. 

Brou de noix2.jpg


This research is unfinished, speculative, weird, useless, a waste of time, fun, inspiring, boring, crazy, interesting, wicked, psychedelic, bland, etc. In a nutshell it is work in progress. Mainly ideas and pieces of code that have not been published or ended up in a product. I will use this part of the web site as a forum for such material.




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