My research has spanned a range of topics in computer vision and machine learning. Much or my work has focused on problems in visual object recognition. I have also done a good deal of work on understanding how to account for variations in lighting when recognizing or reconstructing objects. I have also been interested in a variety of other problems in vision, including image clustering and structure-from-motion, and in the intersection between vision and user interfaces and vision and graphics. Our group is applying some of this work to building electronic field guides. Our iPhone app, Leafsnap has been downloaded by more than 1,500,000 users. We have also developed Birdsnap and Dogsnap.