afar

It's a custom sensor in the lidar family. Uses infrared lasers as illumination and generates depth data. Essentially millions of height values. When depth is rendered to be human legible it look looks like greyscale silhouettes (dark grey is far away, lighter gray is nearer). Sensor processes those values on the edge and published +1/-1 and telemetry data (system health).

The bet is that by giving data back to people to let them make their own decisions about safety, they'll self moderate.

Def. We call that the OB1 problem (off-by-one). If either event detection (did something happen) or event classification (entry or entrance) is wrong, you can be off the whole day. To solve that, we have a different approach / non-threshold approach for boolean occupancy. Not implemented here.

More difficult with multiple doors when you have radio between to reconcile count.

Accuracy is fundamental. When installed properly, a 99%+ f1 score is achievable.

Yeah. Should have been "Safe by reducing Density"

Nets out to ~$85/mo. For a small place, that's substantially less expensive than staffing it full time.

disclosure: co-founder here.

What do you think is the biggest blind spot or most limiting aspect of YC Group and how do you plan to fix it? Asked another way, what are YC's weaknesses, in your opinion?

No worries. I totally earned that one.

You're right. It was an unprofessional comment. I was flippant and insulting. You are also certainly right to be disappointed, off-put, and impressed with how PM responded.

Product of tiredness and being trigger-happy with the reply button today.

Apologies to dfine and Placemeter.

Sorry. If you can email team AT density.io with a bug report or something that shows the latency that would be really helpful.

[Density founder here] Hey Animats, sorry it took me all day to get to your list of questions.

> which implies they're selling data to someone else. Who?

Typically our customers are startups who sell to SMBs (coffee shops, bars, restaurants, museums, etc). They charge merchants anywhere between $50-$500/mo/location for some kind of software or service. These are startups that sell POS systems, loyalty software, marketing services, discounts, handle logistics, and delivery.

> There's no privacy policy. No terms of service.

Frankly, it should have been there before launch but since people don't "buy" through our website, we decided to sacrifice legal thoroughness for speed to launch. Maybe a misstep but people seemed okay emailing us their request to order.

> How does the device tell how many people are present based on counting at a doorframe?

Two closely situated, parallel infrared distance sensors. We timestamp spikes in voltage as they come in allowing us to see o...1 = entrance. 1...0 = exit. Giving us the current count in a place.

> Is it counting people passing through the door? Direction?

Yes. Not the line outside. Although we can do line detection and estimate wait times. Yes.

> Is it good enough to estimate the number of people inside by subtracting out counts from in counts?

Yes. It's better than just an estimate.

> Will this work for wide entrances, such as malls? Is this a passive infrared sensor?

No. Our current model maxes out at roughly 90in -- that's with two sensors on either side of a double door facing one another. No it's AIR.

> 98% count accuracy ... If you already have surveillance cameras, you can often use them for counting.

You're right. We're just betting that customer-aversion to facial recognition and surveillance cameras is slowing adoption in the long tail of the market we're after - the various independent merchants and sellers that comprise a city and who are too busy making coffee and food to spend too much time on potential controversial technology. See: http://techcrunch.com/2014/05/29/philz-coffee-drops-euclid-a...

[edit: for readability]

[a Density founder here] Okay...

> Why does this need to connect to your servers? Because that's where the signal gets processed. We store all signal data ever captured and do all the math on an analyze server. The benefit of this is that as our hardware can be cheap enough to replace or give away and when our algorithm improves so too does all historical data.

> What happens if you become insolvent? Not sure yet. What happens if any of your providers become insolvent?

> Why can't I just buy the damn thing then use it? Because there's no margin or recurring value in the damn thing. And selling hardware is a bad idea right now.

> Why do I have to pay for a subscription to a service which is effectively a simple proxy between the device and my infrastructure? Because we're not selling the device. We're selling the analyzed data. Also, I should probably say, you're not our target customer. We're after companies that control / manage large networks of locations not individual developers.

To be honest, we'd love to give this to any developer who wants it and just see what they build. Hopefully, we'll be able to do that someday and support that community properly. Until then, this is the best way for us to be a sustainable business and not rely on the crazy thin and ever-decreasing margins of hardware sales.

Hope that addresses some of your questions.

Andrew

Hardware's intentionally simple. We've even considered open sourcing it :).. [Density founder here]

I really like you, for some reason. I think it's your green handle.

That's really interesting. Given a certain level of granularity, would it be possible for a person to have a unique object signature? I guess at that point, you'd just use a face. Just curious.

No wifi pinging. After Apple almost killed us a year ago with their MAC address policy change and we realized there was significant push back on privacy, we dropped the technology altogether.

I am curious. Particularly with your new sensor. It sounded like much of the video processing happens on the unit itself, meaning faces never reach Placemeter servers. Is it accurate to say that you're only getting counts and movement data?

My other question is how you derive count without uniquely identifying someone. If I'm entering a shop and a PM sensor sees me, will it know when I leave?

I agree. But I think there should be a distinction between being on someone's property and being recorded for security and being in a cafe, having your face recognized as someone that frequented a sex shop last week, pairing that with an online profile, and then being pushed a retargeted ad campaign about your fetish.

We agree. That was not by design. Updating.

Yeah. We could and will clear that up.

Yeah... I mean I appreciate that people pay lip-service to privacy but a surveillance camera that counts you as a distinct individual without your consent is an invasion of privacy. The cost is higher than the price tag, homie.

Edit I am an employee of Density and definitely biased.

Cheap and anonymous by design. Also, we're not after big retail. We're after everyone else.

At one point we went as far as to quiz our moms. "Mom, what does Density do? What does it cost? Do we sell surveillance cameras?"

After she got 9/10 correct (she's 58)... she looks at me and says, "Ship it, Andrew. Ship it."

Yeah... we're secretly hoping for some version of https://en.wikipedia.org/wiki/Schrödinger's_cat

So that's a really novel idea. It would be incredible to tell a first responder how many people we think are inside... accurately.

We just do installs at each entrance and then normalize.

Thanks. Took a long time to get the right balance of imagery, icons, and copy.

Yeah. Currently we piggy-back on a locations wifi. Relatively low upstream data (37kb / 90secs).

We've considered things like Helium. Eventually centralizing the network will be good but for now, wifi's cheap and available.

Foot traffic should be inexpensive, accurate, and available in real-time. It should be dead simple to integrate with other applications, and it should never invade people's privacy.

imo.

Why is getting a warrant not enough? Seems the level of access and cooperation is as much or greater than a key or backdoor.

Isn't it relatively speedy to get a warrant? In some cases just hours?

Fascinating. Wondering what their tax rates look like...