PhD candidate Greg Philbrick receives Faculty of Mathematics Graduate Research Excellence Award

Monday, February 28, 2022

PhD candidate Greg Philbrick has been awarded a Faculty of Mathematics Graduate Research Excellence Award. The prestigious recognition comes with a cash prize of $5,000 and is conferred annually to a master’s or PhD student who has authored or co-authored an outstanding research paper.

Greg’s paper, titled “A Primitive for Manual Hatching” and co-authored with his advisor Professor Craig Kaplan, was published in ACM Transactions on Graphics, the premier venue for research in computer graphics.

photo of Greg Philbrick

Greg Philbrick is a PhD candidate at the Cheriton School of Computer Science, advised by Professor Craig Kaplan. He has a Master of Science degree in computer science from Brigham Young University and he has worked as a software engineer at Stellar Science, a software company that provides scientific analysis software. Greg brings an artistic sensibility to his research on computer graphics.

Hatching is a technique in art used to create tonal or shading effects by drawing closely spaced parallel lines or curves. Hatching has been used for centuries in diverse media; however, even skilled artists find hatching patterns difficult to draw and more challenging still to edit.

To make hatching illustration easier, Greg developed the hatching shape, a drawing primitive for use in digital art and illustration software. Hatching shapes automate the placement of the many fine lines that constitute hatching, while giving the artist control over the direction, width and spacing of the lines. 

“I enjoy making art and I wanted to develop a tool that helps artists,” Greg said. 

illustration showing the hatching shapeTo this end, he built an interactive illustration tool in C++ that takes input from a drawing tablet and uses OpenGL to render a virtual canvas. It has many of the features of digital drawing tools along with the ability to create and edit hatching shapes. 

“When you’re drawing a three-dimensional object from imagination in two dimensions — using a single pattern of lines to render the whole object — you often need to have the pattern be discontinuous. A major contribution in the paper is barrier curves, which are used to create these discontinuities. For example, in the illustration of the man holding an egg, discontinuities are used to create the musculature of the arm and the edge of the right shoulder blade.”

Another important contribution is multi-dir, a facility to control the direction of hatching marks by interpolating a smooth direction field from guidelines sketched by the artist.

Greg explains, “Editing the direction of the lines in a hatching shape is even more useful for illustration than editing the spacing and width of lines. I want to alter the direction field so hatching lines follow a complicated form, and I want to be able to do it in a way that allows some trial and error to hone in on a solution. Hatching by hand is incredibly difficult and time consuming. And if you get it wrong, you have to erase the lines and start again. Multi-dir provides a shortcut, a way of altering the direction of hatching lines iteratively or by trial and error to get the result an illustrator wants.”

“Greg’s research paper is a significant contribution at the intersection of computer graphics and art,” said Professor Kaplan. “His own artistic practice was key in generating new research ideas relevant in real-world digital art, and his technical skills allowed him to develop a fully featured software prototype to demonstrate those ideas. He has used his software to create a large collection of drawings that has received compliments from professional artists.”

To learn more about this award-winning computer graphics research, please see Greg Philbrick and Craig S. Kaplan. 2022. A Primitive for Manual Hatching. ACM Transactions on Graphics 41, 2, Article 21.

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