Edit 2019: I have converted the original slides to PDF format and also made minor corrections. See this post for details. The download is at the end of this page.
I was kindly invited by Wolfgang from Confetti FX to speak at the FMX 2013 conference about physically based shading (within the scope of the Real Time Rendering day). Since I remembered the FMX as a conference for visual arts, I made the presentation intentionally non-technical, for fear of alienating the listeners. In retrospect, my guess was a bit too conservative, as there were quite a number of programmers in the audience.
Nevertheless, here are the slides for download (with all notes included). The Keynote format is the original and the Powerpoint format was exported from that and is a little broken, so you should use the Keynote version if you can read it.