Now a startup that automatically monitors headcount indoors has raised $51 million as limits on gatherings during the pandemic ushers in a fresh wave of demand for the business.

San Francisco-based Density, which uses sensors to monitor the number of people entering and exiting a room or building, announced Tuesday that it raised the Series C funding with Kleiner Perkins leading the round and substantial capital from 01 Advisors. Other investors included Upfront Ventures, Founders Fund, Ludlow Ventures, Launch, DTA, Alex Rodriguez, LBC Ventures, Julia and Kevin Hartz, as well as Cyan and Scott Banister.

Prior to the pandemic, Density’s main pitch was space optimization: Using Density, businesses and real estate investors could analyze which commercial properties were being under-used with its sensors and software, and cull wasted rentals and buildings. And for those who know the pain of lining up at the Department of Motor Vehicles, the startup may also be remembered as one that sought to kill the lines at the DMV.

With an easily spread virus that’s required social distancing, companies, says CEO and Co-founder Andrew Farah, have sought to control the number of employees and customers indoors.

“Prior to COVID, this was an important and material thing for those that led large real estate portfolios,” says Farah. “In the pandemic this is a mainstream issue.”

Stores are using Density to display the number of people inside with iPads at the door, for instance. And while work-from-home has become the norm for many large companies, businesses such as manufacturing, food production, and shipping logistics are still bringing workers to work—all sectors where Density says it has experienced a flood in inquiries.

Meat processing plants, where workers often stand shoulder-to-shoulder, have experienced outbreaks that fanned fears of shortages around the country. In one case, says Farah, a meat plant became a customer after two coronavirus outbreaks led the company to seek ways to limit its worker concentration.

While Farah declined to give specifics on revenue and valuation, he says new bookings grew 493% in the quarter beginning February compared to the quarter prior.

Data privacy

Density uses a laser-based depth sensor, a small square rigged to doorways, that bounces infrared lasers off of objects to determine height values.

So there are ways to trick the technology, says Farah. Pop up an umbrella. Or, if you feel so inclined, walk under one under all fours and you might just fulfill your childhood fantasy of becoming a dog—at least in a machine’s eyes. But these, says Farah, are “edge cases.”

Which also means the sensor cannot tell who exactly is walking under the doorway. At a time when consumers are becoming increasingly wary of data privacy, Density also prides itself on anonymized data. The company can tell which location is being entered and exited, but it can’t determine for example the IP address of the person walking under the doorway or their face. When asked if the company would be open to sharing information to governments, Farah says Density doesn’t plan to sell customer data to the the group.

“Governments are customers,” says Farah. “But at present, we don’t sell or intend to sell, or give customer data to the government.”

Density says was planning to raise in 2020 to begin with, but it wasn’t sure when. The uncertainty only heightened when the pandemic hit. But as business accelerated, it launched the funding round in May. While business has boomed, one trend has not abated: “The pandemic has introduced enough uncertainty that I’m not ready to commit to a specific headcount for the next 12 months,” he said.