It's common knowledge that San Francisco has a serious homelessness problem. Estimates of the size of the city's streetbound population vary between 6,000 and 10,000, depending on the source. But that population, largely confined to a few nonresidential downtown neighborhoods, can too easily become invisible to most residents.

One thing isn't invisible, however: the problem of human poop on sidewalks. Since the city slashed funding for Parks and Recreation in 2009, there's a distinct shortage of working public bathrooms. And that led to a spike in reports of public pooping to the city's 311 help line.

Web developer Jennifer Wong (a.k.a. mochimachine) created the Human Wasteland map out of that public data. The project, which won Zillow's SF office Fall 2014 Hack Week contest, offers monthly maps from January to June 2013 — but that's enough to give you a sense of where the problem is.

"It's easy for people to place blame on the homeless themselves," Wong tells Mashable. "But they need to take a look at the bigger picture and see that they have nowhere to go, to sleep, use the toilet, to shower ... the obvious solution is to provide more public facilities throughout the city. Just six months of data is enough to show where there is the greatest need."

Some entrepreneurs and nonprofits are attempting to address the problem by novel means — such as the Google-funded Lava Mae, which converts old buses into mobile shower and toilet stations.

"The city is making some moves in the right direction," Wong says. "But there has been and is still a long, long way to go."

The map was first reported by The Bold Italic, which also published this excellent backgrounder on the city by the Bay's big poop problem last year.