Hold on to some of that geometry you learned in 10th grade — it might come in handy later, especially if your job is to paint one of the tallest murals in the city.

New Orleans-based street artist Momo used practical geometry to design the towering new mural going up on the side of the Sonesta hotel at 18th and Market. The technique, employed by masons and carpenters (though less often now in the digital age), is a straightforward way to map out geometric shapes. Momo explains his process of transforming a design into a mural with practical geometry as a “direct scaling of designs from notebook to wall. … The tools scale up and down by their nature.”

“The economy of means is attractive,” he continues, “pulling endless patterns and perfect polygons from just a nail and string. The details come for free, from nature.”

Related: Walk through Sam Durant's 'Labyrinth' for Open Source

Momo’s distinctive murals — seen everywhere from the John Hancock Tower in Boston, to a school in Besacon, France, to a collective art studio in Tulum, Mexico — are abstract: bright colors intersect as tightly formed geometric shapes, some made of perfectly spaced series of curved lines, like grooves on a record.

He describes his work as “concrete” and in line with “the language of architecture, so we confront buildings on their own terms” as opposed to creating visual illusions such as 3D. The art is doesn’t demand “a trompe l'oeil fantasy on the part of the viewer,” he says.

The Sonesta mural is Momo’s second project in Philly for the Mural Arts Program's “Open Source: Engaging Audiences in Public Spaces,” which includes 16 artists, both local and visiting, working on 14 large-scale projects. His first, already completed, is in Fishtown, where Momo worked with students from the Kensington Creative and Performing Arts High School and Freire Charter School through Mural Arts’ art education program.

Momo taught the concept of practical geometry and using math in art in the classroom, then collaborated with the students to create the new mural on Frankford Avenue.

“These ancient and eloquent techniques of craftsmen, draftsmen and architects bleed freely into areas of music theory, cosmology and science,” he says. “It’s fascinating to think that simple constructions on a wall or notebook can touch such a vast history of curiosity and achievement coming from virtually every culture.”

See the art

Jane Golden, director of the Mural Arts Program, is hosting an "Open Source" walking tour on Sunday, from 11 a.m. to 12:30 p.m. The tour meets at the Open Source Hub on the first floor of the Graham Building (30 S. 15th St.) and goes to works by several artists, including Momo.

If you can't make this one, there's another walking tour on Oct. 25, led by Open Source curator Pedro Alonzo. Each tour is $25.