In addition to his unassailable reputation as a painter, Piero
has long been considered a kind of "mathematician," largely
because Giorgio Vasari, writing in the mid 1500's, said he was.
Until the 20th century, however, there was no firm evidence
on this point. The belated discovery of three manuscript books
by Piero changes the picture
completely. It has taken almost another 100 years for people
to begin to look at these books as serious works of mathematics.
The article describes the kind of mathematics to be found in Piero's work. It is far beyond anything his contemporaries were doing, meaning that Piero was not just among the great painters of his century, he was without question the greatest mathematician of the 1400's. The article is available in preprint form as a gzipped Postscript file (5 figures + text).
Here are some other Piero sites: