Although dead at the young age of 36 from leukemia, Marr's computational and mathematical approach to vision revolutionized the entire area of vision research, after which it was never the same. There are strong hints of this approach in the earlier work of Julesz and Gibson, but Marr's work takes the whole field a quantum leap further, giving it a rigorousness and mathematical elegance never before seen.
For example, to mention just a few of his important ideas, Marr's demonstrations that retinal receptive field geometry could be derived by Fourier transformation of spatial frequency sensitivity data, that edges and contours could be detected by finding zero crossings in the light gradient by taking the Laplacian or second directional derivative, that excitatory and inhibitory receptive fields could be constructed from "DOG" functions (the difference of two Gaussians), and that the visual system used a two-dimensional convolution integral with a Gaussian prefilter as an operator for bandwidth optimation on the retinal light distribution, were more powerful than anything that had been seen up to that time.
It was as if vision research suddenly acquired its own Principia Mathematica, or perhaps General Relativity Theory, in terms of the new explanatory power Marr's theories provided. Truly an extraordinary book from an extraordinary thinker in the area of perception, vision, and the brain.