Tuesday, July 30, 2019

Tribute to Godfried by one of his former Ph.D. students, Jörg-R. Sack

I have the pleasure of being one of Godfried’s “children”. Having arrived at McGill, I was initially
working in a Biomedical Image Processing Lab. Godfried approached me, after I gave a talk in
his Pattern Recognition class, to switch and work on my Ph.D. with him in the then fairly new
field of Computational Geometry. I said that I did not know Geometry well enough to work in
CG. He responded: “neither do many in the field – so don’t worry; the field is young and

I learned a lot from him. He was excellent in collaborating, presenting material, opening new
areas of research, making sound conjectures, having excellent intuition, crafting well-written
papers, and teaching algorithms with skillful illustrations. He loved to teach CG and students
remarked: “You give Godfried any course to teach, he will find a way to teach CG”. At times, in
his classes, he would include incorrect algorithms to reenergize us and would then request
that we find counter-examples. (This included e.g., several wrong linear-time convex hull
algorithms for simple polygons.) I try to maintain his tradition of teaching. His standards were
very high and his graduate students would, at times, be frustrated by his many demands for
stylistic changes to draft papers, but were very happy with the eventual outcome.

He also had tremendous artistic skills incl. a passion for drumming and dancing. His artistic side
also strongly influenced his research in a number of ways: from choice of problems through
crafting of illustrative examples and presentation style.

It was an exciting time for me to be in the CG group at McGill from 79-83. Visitors were
frequent, conferences few, so you were able to meet all the people in the field regularly.
Godfried was a central figure and helped me make life-long connections with now dear
colleagues and friends. I am very grateful also for that.

Thank you for all you have given to me and to the field. You are deeply missed, Godfried!