# Podcast: Episode 23 – Paul Shepherd, Decimation and Subdivision

These are the show notes for episode 23 of the Travels in a Mathematical World podcast. Readers of this blog will know I am relieved to have remembered to note that 23 is prime. 23 is an interesting number thanks to the birthday problem: In a group of 23 or more randomly selected people there is a more than 50% probability that a pair of them will share a birthday. You can read a serious article on the Birthday Problem at Wolfram MathWorld, or a more light hearted one at Damn Interesting. More about the number 23 from Number Gossip.

This week on the podcast we hear from Dr. Paul Shepherd of the University of Bath. Paul is a mathematician working in the Department of Architecture and Civil Engineering and speaks about two aspects of 3D modeling – decimation and subdivision. Decimation is the process of simplifying a computer model of a 3D shape by selectively reducing the number of triangles used to make up the model so it can be practically handled inside a computer. Subdivision is the opposite process, in which a very simple 3D model has extra triangles added to make it look more realistic. Paul also talks about what a mathematician can bring the world of engineering and architecture. There is more information on Paul’s work in these areas on his website.

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