In 1970, he began teaching at MIT and continued teaching there for the next 4 decades, becoming associate professor in 1976 and Professor in 1984. In 1983, he was appointed as the Associate Editor of Computer Vision and Image Understanding. He also serves on the editorial board of International Journal of Computer Vision. Horn was instrumental in the conversion to scalable, hinted outline format (Adobe Type 1) of
Donald Knuth's
Computer Modern fonts, The
American Mathematical Society (AMS) fonts,
LaTeX fonts,
Michael Spivak's
MathTime and MathTime Plus, as well as
Charles Bigelow and
Kris Holmes'
Lucida Bright, Lucida Bright Expert and Lucida New Math fonts, all used in mathematical typesetting.
Research Most of Horn's research has been focused on machine vision, particularly so-called "physics-based" machine vision, going back to the beginnings of the field in the 1960s. His thesis entitled
Shape from Shading: A Method for Obtaining the Shape of a Smooth Opaque Object from One View was one of his first works in this area. Much of his work in the 1970s and 1980s is focused in this area on the topics of
optical flow,
photometric stereo as well as closed-form solutions of orientation problems of
Photogrammetry. During the 1990s, Horn's research interest began including Computational Imaging, which is the creation of an image based on raw measurements that are not directly related to local brightness or density values, but nonetheless capture some information about spatial distribution of matter. Some of his early work in computed tomography (CT) led to methods for reconstructing from fan-beam scans, which do not lend themselves to the widely known Fourier-slice theorem used for parallel beam scans. Through time, his research in this area moved towards structured illumination microscopy (SIM) and high resolution X-ray imaging, including phase reconstruction. In 2013, Horn presented an algorithm at the IEEE Conference on Intelligent Transport Systems for reducing the problem of phantom traffic jams. He and his team studied traffic congestion and proposed that avoiding tailgating could decrease traffic jams. Their research proposed that keeping an equal distance from the car in the front and the back can reduce congestion and decrease commute time. They named their method the bilateral control. The research was published later in the IEEE Transactions on Intelligent Transportation Systems. The team developed an algorithm that dictates exactly how fast a vehicle should travel to avoid congestion. Horn proposed that their algorithm could be used to improve the cruise control systems on cars. Their later research was funded by Toyota. In this area, Horn is also working on improving vehicle safety and passenger comfort using inverse-time-to-contact (TTC) for control. In the late 2010s Horn research also began including the topic of indoor location by means of Fine-Time-Measurement of Round-Trip-Time of electromagnetic waves at Wifi frequencies as a possible source for turn-by-turn navigation for the visually impaired. == Books ==