On the evening of November 17th, tens of thousands of Occupy Wall Street protesters marched throughout New York City, many making their way on to the Brooklyn Bridge, carrying LED candles and chanting. As Occupiers took the bridge in a seemingly endless sea of people, words in light appeared projected on the iconic Verizon Building nearby.

A few hours later, creater Mark Read, who organized the "bat-signal" project, told Boing Boing why and how he did this, and what technology he used:

"It came up at an action coordination meeting. We were talking about what to do on the 17th. We had a sense that the morning on Wall Street would be forceful and confrontational, and we wanted to not do the same kind of thing in the afternoon. Initial talks focused on having a thousand people taking the bridge in the afternoon, and continuing in a militant mode of activism. But we started thinking about creating a more unifying moment. A celebration of the birthday of Occupy Wall Street. Maybe taking the roadway and having lots of arrests might not be best thing. What if we took the pedestrian walkway, and gave out LED candles? We would give out 10,000 LED tea candles, a river of light streaming over the walkway."

"And a guy named Hero, who has been central to a lot of facets of the occupation since the beginning, turns to me and says, 'We need a bat signal. The 99%.'"

"I said, I think I can do that. I know just enough about how the technology works that I think I can pull that off. And for the past two weeks, I've worked full time on figuring that out."

"My friend Will Etundi...he's part of a community of friends who deploy spectacle and art... Will and I have done other events that were about getting people into public space. Transforming the normal way we use space, turning it into a party, a roving community, something festive and mobile. Through that work, I'd already met people with a variety of skill sets, strange and magical abilities. I got in touch with them right away, and started pulling together a team. Who would have a 12K lumen projector, a big expensive piece of equipment, the most powerful projector you can get?"

"I knew I wanted to throw it on the Verizon Building. Everyone who lives in New York has looked at that big monolithic structure. For some of us, every time we look at it we think of how cool it would be as a projection surface."

"I knew we'd need a powerful projector. But if you had something that expensive on loan for free, you couldn't just sneak it up on some roof and be in jeopardy."

"I knew I had to find someone who lived in a building nearby."

"Opposite the Verizon building, there is a bunch of city housing. Subsidized, rent-controlled. There's a lack of services, lights are out in the hallways, the housing feels like jails, like prisons. I walked around, and put up signs in there offering money to rent out an apartment for a few hours. I didn't say much more. I received surprisingly few calls, and most of them seemed not quite fully 'there'.. But then I got a call from a person who sounded pretty sane. Her name was Denise Vega. She lived on the 16th floor. Single, working mom, mother of three."

"I spoke with her on the phone, and a few days later went over and met her."

"I told her what I wanted to do, and she was enthused. The more I described, the more excited she got.

Her parting words were, 'let's do this.'"

"She wouldn't take my money. That was the day of the eviction of Zuccotti, the same day. And she'd been listening to the news all day, she saw everything that had happened."

"'I can't charge you money, this is for the people,' she said."

"She opened up her home to us. She was in there tonight with her 3 daughters, 2 sisters. The NYPD started snooping around down on the ground while the projections were up, it was clear where we were projecting from, and inside it was festive."

"'If they want to come up they're gonna need a warrant!,' her family was saying. 'If they ask us, well, we don't know what they are talking about!'  They were really brave and cool."

"I [wrote the words]. A lot of it is just chants that we've heard. 'We are the 99%,' everyone knows that one. 'We are unstoppable, another world is possible,' a bunch of chants that have circulated around. 'We are winning.' ...And, 'It's the beginning of the beginning.'  I loved that one. So frequently, things happen in the world that make it feel like we're at the beginning of the end. But—'the beginning of the beginning,' what a radically optimistic statement that is."

"The scale of the environmental and economic crisis we are facing, it's extraordinary. This movement is a response to that crisis. Our leaders aren't responding to any of that in a way that is commensurate to the crises we face. And that one sign has always spoken to me. We have to throw off our despair about the future world we might be facing, because if we come together as people and humanity, we can change it. And what Occupy Wall Street makes me feel is that for the first time in a long time that might be possible."

"That means a lot to me. This is choosing hope over despair. This is actively and resolutely making that choice. It's not going to be easy. It's not going to be over in two months. It's not going to be just the result of conversation."

"I'm 45. The people who worked on this are a diverse range of ages. Some are in their 20s, but not all of us are that young. It's hard to study what's happening in the environment and with the global economy and not feel afraid. There is a lot to fear. One of the things we were projecting tonight, it was Max Nova's idea, 'Do not be afraid.' And I think that's so important."

"I watched 9/11 happen from my rooftop in Park Slope. I was there. It's been a crazy decade since then, a fearful time. And our leaders have stoked those fears, there's been a lot of fear-mongering. It's been like that for a decade, and it feels like we are turning a page. I know we're heading into winter in New York, but this feels like springtime."

"Max Nova and JR Skola from the art group, Dawn of Man [were responsible for creating the sequence, and projection]. They are video projectionists, and artists.  They have done stuff in Zuccotti Park. I didn't know how I was going to put together the graphics, I'd been running around for the last two weeks trying to coordinate the team—you have to be able to live mix it, you need to understand how to make projections look right coming to the surface from an extreme angle, you need to be a VJ, and I'm not. So Max wound up being the guy. They used Modul8 VJ mixing software, a Sony 12K lumen projector that sells for around $10K. It's huge. It's more than 3 feet long, about 2 feet wide."

"The whole thing was a combination of high tech and super jerry-rigging on the fly. The Modul8 software we were using can do amazing things: sense the angle you're projecting at, even if it's extreme, and modify the image so it looks straight. But then, we held the projected in place with gaffer tape, a broomstick, some baling wire. We only had 20 minutes to get it ready."

"I was so sure it was not against the law, but I didn't ask my lawyer friends. I didn't want to really know. The police knew where we were, they were pointing up to the window. But no one stopped us when we left."

"Oh, we could hear the crowd from the window [the estimated 30,000 Occupiers as they were marching on the bridge and saw the projections]. We heard them screaming, yelling. We had this idea that we would be able to mic check a short speech, and we timed the words so that it would fit with exactly how people would chant, just as they had been chanting these things for weeks."

"I feel immense gratitude to these youngsters for kicking my ass into gear. I'm feeling so much gratitude to everyone, for putting their bodies on the line every day, for this movement. It's a global uprising we're part of. We have to win."