
Show HN: Density – Anonymous People Counter and API - jordanmessina
http://www.density.io/?ref=hn
======
Animats
The site is rather vague. They provide the hardware and install it for free,
which implies they're selling data to someone else. Who? There's no privacy
policy. No terms of service. The "order" button just brings up a blank email.

How does the device tell how many people are present based on counting at a
doorframe? Is it counting people passing through the door? Does it detect
direction? Is it good enough to estimate the number of people inside by
subtracting out counts from in counts? Will this work for wide entrances, such
as malls? Is this a passive infrared sensor? Those go blind in hot weather.

This looks like a cheaper alternative to video counting systems, of which
there are many. Video systems get about 98% count accuracy. If you already
have surveillance cameras, you can often use them for counting. Beyond that,
there's queue measurement - not just how many people are in line, but how many
gave up and left without buying.[1] (Seven people in a queue is the tipping
point – any longer and most shoppers won’t bother joining it. After 9 minutes,
shoppers are likely to give up queuing and leave empty handed (other research
says as little 6 minutes). 70% of customers who leave never come back.)

[1] [http://www.retailsensing.com/queue-
management.html](http://www.retailsensing.com/queue-management.html)

~~~
afar
[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...](http://techcrunch.com/2014/05/29/philz-coffee-drops-euclid-
analytics-over-privacy-concerns/)

[edit: for readability]

~~~
jondubois
>> 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

What if someone waved their hand in front of it (in a particular direction) in
an attempt to subvert it? Couldn't someone trick it into over-reporting or
under-reporting the number of people inside?

What if someone is standing idle in front of it (near the door frame) for a
few minutes and in the meantime a large number of other people walk in? Will
it miss them?

What if two or more people walked in at the same time with no gap between
them?

Most importantly: How would the counter ever be able to correct itself from
inaccuracies?

------
dhaivatpandya
Fantastic product idea and a landing page that's so good that I figured out
what the product does without touching my scroll wheel.

I wish however, you'd include a section that provides a reasonable explanation
as to _why_ Workroom got a 950% increase in traffic. I'm thinking that if I
saw that a place was full, I'd be less likely to head over there. But, if I
didn't know, I'd probably give it a whirl. Alternatively, if I've gone there a
bunch of times and it's always been full, I just wouldn't go. What exactly is
happening?

~~~
crindy
I think the idea would be that this helps fill dead times. If the place is
full, they don't need/want more people showing up just to be turned away. If
the place is empty, then they want to advertise that to fill it back up.

Also though, I think it was a 950% increase in traffic to the web pages
powered by this product, not to the actual locations.

~~~
jordanmessina
Right, the increase was on the webpages that included Density to show seating
capacity.

~~~
escobar
I also find this particularly confusing/misleading - since you deal mainly
with physical locations (often called sites by owners), using the word "site"
instead of "web traffic" seems odd. Also, listing a web based metric as large
as 950% without any type of time interval really kills the true significance
of that metric.

~~~
sultanofsaltin
My favorite statistic: 73.6% of all statistics are made up.

My 2nd favorite: 950% of 0 is 0.

------
codeshaman
>> "After adding Density, we saw as much as a 950% increase in site traffic to
supported locations. Our users love it." \- Darren Buckner, Workfrom CEO

When I use google maps, it shows me how busy various roads are and it also
chooses the fastest route based on how fluid the traffic is. Seems like google
maps is just observing the world and making decisions based on those
observations.

Now I was wondering, what if all the drivers used google maps at the same time
?

Wouldn't it mean that google maps is influencing and even _creating_ the
traffic patterns ?

Same here - just measuring the 'density' has the effect of actually
influencing it which is an interesting outcome and resembles quantum mechanics
voodoo stuff :).

~~~
pdeuchler
I live in Boulder and this happens all the time during ski season. When
traveling towards I-70 there's a longer, more circuitous route which breaks
off of Highway 6 and goes through Idaho Springs. This path is longer, but cuts
off the beginning of the initial drive into the Front Range... it's also just
a two lane mountain road.

Sometimes google maps will detect heavy traffic on I-70 and start re-routing
drivers the other way... unfortunately this very quickly creates a bottleneck
that Google Maps can't detect in time (traffic goes from 0mph to 60mph to 0mph
in the mountains) so it'll continue to funnel people down that "shortcut"
until the traffic essentially equalizes with the I-70 traffic.

There's an even worse side effect, as those who went through Idaho Springs
eventually have to get back onto I-70 to get to the ski resorts, so now that
on ramp (which is a metered on ramp) backs up, further hurting both I-70 and
the "shortcut" traffic. It's a real terrible feedback loop that essentially is
caused by Google Maps not being able to adequately predict how much traffic
the Idaho Springs route can handle, which seems like a hard problem to solve
(especially generally).

Edit: Thought about this more and realized predicting ski traffic is more or
less a proxy for predicting the weather, so I highly doubt this is a fixable
problem (at least in this specific case)

~~~
toomuchtodo
Would you be willing to report this to the Maps team? If not, just reply and
I'll get in touch with someone about it.

~~~
pdeuchler
Can't seem to find where to file this bug since it's not a physical mapping
error. Coincidentally the Maps team is in the Boulder office, are they not? I
guess I could just walk down and say hi :)

Feel free to connect me with the right people, my email is in my profile

~~~
toomuchtodo
Try this:

[https://support.google.com/gmm/answer/6194894?hl=en](https://support.google.com/gmm/answer/6194894?hl=en)

\----

Your directions were wrong

At this time, you can’t report wrong turns from your phone or tablet, but you
can report them on your computer.

Open Google Maps on your computer. Click Directions directions button image.
Enter the starting point and destination for the route for which your
directions were wrong. In the bottom right of the map, click Report a problem.

\----

I'm working on getting a human contact involved.

------
web007
Please don't be too clever for your own good - let me Cmd-Click on the links
to open in a new tab.

I don't want to be taken away from your page, I want to continue reading more
about YOUR product before I go to view your "partner" sites. Same goes for
your API, Twitter, etc.

~~~
bryans
This is obnoxious website behavior, and I equate it to sites ignorantly
disabling right-clicking because they're paranoid someone will steal their
photos. If your site contains any links at all, you should never, ever be
breaking such basic browser functionality. The only possible legitimate use
case would be a webapp which is attempting to create a desktop-style
environment, and even then, co-opting the CTRL or ALT keys is likely not the
best course of action.

~~~
willlll
I disable right click on my Website.

~~~
icelancer
For what reason? This is easily bypassed.

~~~
Nadya
If you visit his website [0] it's (at least I hope) intentionally poor
designed, everything terrible straight from the late 90's in web design. From
marquee, blinking, embedded mp3, and more.

There's a built-in bypass in the site.js to allow the context menu if shift is
held, though you still get the alert. Or it's just that holding shift allows
the context menu to appear after the alert. I don't actually know.

    
    
      document.body.oncontextmenu = function() {
        alert('Please dont right click!!')
        return window.event.shiftKey // top secret
       }
    

[0] bitfission.com

~~~
geofft
That is an amazing website, including the MP3-rendered MIDI, and I'm now
pretty sure the comment was a joke that everyone missed :)

------
tyho
Why does this need to connect to your servers? What happens if you become
insolvent? Why can't I just buy the damn thing then use it? Why do I have to
pay for a subscription to a service which is effectively a simple proxy
between the device and my infrastructure?

~~~
soggypretzels
That is my biggest thought. If this is oriented to hackers, let me own the
thing so I can do some _really_ cool stuff with it.

~~~
tyho
I hate this user hostile trend among hardware startups, that is
requiring/involving third party "cloud" infrastructure for no particular
reason other than to extort money out of customers.

~~~
mng2
The hardware sounds dead simple, not to mention cheap. The service is the
actual product here.

~~~
PascLeRasc
I don't think the hardware is simple. How would you design something like
this? I've thought about this problem for years and no elegant solution has
occured until I saw this.

~~~
icelancer
Hmm? Two beams detecting directionality + WiFi?

------
robotnoises
Had no idea what this was. Clicked link. Within one minute I figured out what
Density is. Nice job on the landing page!

IMO, this is the strongest section:
[http://www.density.io/#comparison](http://www.density.io/#comparison)

~~~
afar
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."

~~~
toomuchtodo
"Hacker News Tested, Mom Approved".

------
sultanofsaltin
Don't camera systems beat this in pretty much every way?
[http://www.placemeter.com/](http://www.placemeter.com/) comes to mind.

You don't have to resort to infrared sensors in order to provide anonymity,
but they do inherently limit you potential accuracy and metrics you can
prodive. It all comes down to where the data is processed and what is made
available. Also, cheap camera components are coming down fast due to economies
of scale, not sure how IR will play out in the long haul.

~~~
afar
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.

~~~
dfine
I am a PM at Placemeter. We do not "use facial recognition software" in our
algorithms, as Density's website claims of video-based systems. None of our
algorithms use biometric markers for our counting—we're essentially the same
"dumb" counters as Density's IR with the added advantage of accuracy and area
of coverage.

Placemeter does much more than pay lip service to privacy. We pride ourself on
our privacy efforts. If you want to lear more about them, @afar email me:
david@placemeter.com

~~~
afar
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?

~~~
dfine
Great questions.

1) the processing is happening aboard the sensor, counts are what are sent
back to the servers

2) we don't do unique identification like that. We use object detection, which
is different than using unique biometric markers like face detection. That
means that we can track a person or a car within a frame of view, but not if
they exit and re-enter the frame like in the case you described.

Does Density still use wifi pinging for part of its counts?

~~~
afar
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.

~~~
dfine
Not quite sure I understand your question. We store counts, not individual
object IDs, so at an individual granularity it would be the same as your IR
device counting one person.

------
lost_my_pwd
Any plans to offer a "disconnected" version where I could push this data to my
own aggregator+API instance? Use case for me would be where foot traffic
numbers would itself be sensitive data.

~~~
jordanmessina
This isn't in the pipeline but shoot us an email and maybe we can work
something out: team@density.io

------
sbuccini
Our student consulting group, Optimir, worked with Density to test their
product around UC Berkeley's campus. It's a fantastic product, and we're
really excited to get these installed permanently in libraries, coffeeshops,
and weight rooms around campus.

------
bgoers
(some) Kroger chain stores have a similar technology [1] to this to determine
how many cashiers are needed at any given time! Neat stuff!

[1] [http://www.informationweek.com/strategic-cio/executive-
insig...](http://www.informationweek.com/strategic-cio/executive-insights-and-
innovation/kroger-solves-top-customer-issue-long-lines/d/d-id/1141541)

------
vosper
Bug report: In Firefox, when on this page [1], clicking on the Density logo in
the top left takes me to
[http://www.density.io/undefined](http://www.density.io/undefined)

Looks like you've got a JS issue in there somewhere.

[1] [http://www.density.io/?ref=hn](http://www.density.io/?ref=hn)

~~~
jordanmessina
Thank you! Fixing it now.

------
agotterer
I have a few questions for the Density folks:

\- How well does it handle people walking in side by side?

\- What about someone pushing a cart or stroller?

\- Can it tell if someone is walking in or out?

\- How far does the laser reach? Would I need two sensors if I had a double or
triple wide door?

\- I assume these are battery powered? How long do they last?

------
aniketpant
I have always wanted to build something like this since I was a kid. The
biggest driving thought was to make traffic signals dynamic and build a
central communication system for a city's transport.

Really glad to see a product coming into the regular consumer space for this
:)

------
Smushman
I spoke with Andrew over at density.io.

His answers regarding can it see the traffic direction (answer - yes for each
individual) and how it is powered (custom length power cable, cut at install
time for both sensor and base) are inline in this thread.

Also Andrew explained the base gathers info from all the sensors for counts.

I asked also about people in a group - most doorways are a physical narrowing
that automatically places people in single file. If the doorway is wider than
that, they can place a sensor on either side (my assumption is that these
results are then filtered so a person is not counted 2x).

------
deutronium
Does this use PIR out of curiosity, or are you using an emitter, receiver in
one package.

~~~
jordanmessina
We’re using infrared sensors. Both the emitter and detector are on a single
sensor, so we only affix our hardware to one side of a doorframe. This is
different than break beam which requires hardware on each side of a door.

~~~
saosebastiao
How much accuracy do you lose when people are dressed up in full winter gear?

~~~
pkelchte
When you would wear metamaterial stealth suits maybe you can avoid being
detected by our IR sensors, we're curious as to what you have available!

~~~
thwest
Incredibly accurate and anonymous seem to be at tension here. A discussion on
your signal processing would be illuminating.

~~~
pkelchte
We made our own AIR door counter, composed of a few distance sensors. It can
tell us in which direction a person is passing, and gives a distance profile
that we process to distinguish individual people. Technically, we measure your
circumference to some degree, but you might agree that is far from enough to
compromise your anonimity.

~~~
thwest
AIR being active infrared as opposed to passive (or a particular waveband)?

Anonymity is a more interesting problem than "can distance sensors uniquely
identify a passerby among 500M North Americans" as your reply implies. What if
you are the roundest or tiniest person in town? All the sudden you are
uniquely identifiable.

You're early in development, and I bet whoever did the circumference
estimation has more in mind. I imagine you could make a good estimation of a
person's height from your data: whether the profile sees knees hips or hands.
Can you identify the asymmetric waist bulge of a CHL carrier? Does your
infrared band penetrate polyesters but not cotton? I hope the reader's
feature-vector blood is flowing at this point.

Your page needs to have way more formalization around the concept of anonymity
(outside of the registration required area) for me to feel that you are
appreciating the problem from an engineering perspective and not a marketing
one.

------
fbr
Looks great! It could be very nice with public transportation, so I'll be able
to know beforehand which wagons are not overcrowded.

------
ChuckMcM
This is pretty awesome. I mentioned doing something like this at the IoT talk
I gave, I had read a paper on counting animals by their heat signature for
conservation purposes and thought something along those lines would be a
simple replacement for the 'walk through the door ring a bell' detectors, and
given that a 32bit ARM Cortex-M is about $1.25 you could do that for not much
more money than the old light + photocell.

Something the paper pointed out was that while the temperature from animal to
animal varied, the _same_ animal often kept the same temperature (+/\-
epsilon) when moving from sensor to sensor and that give some idea of
uniqueness.

And while I also love kefka's solution I think the face recognition stuff gets
a more Orwellian reaction than just tracking heat sources.

------
kefka
Ok. So businesses already have cameras. Yeah, privacy, schmiravacy. That horse
has done gone left the barn.

So, the second problem with cameras/face tracking is cost?

I wrote this:
[https://github.com/jwcrawley/uWho](https://github.com/jwcrawley/uWho)

It does what your hardware does, but also does facial recognition. It's still
early in the build process, but I'm working on a commercial (non-QT) version
of this.

But right now, it can accurately count unique people, as well as remember
people. So when Jane walks in front of the camera, it remembers that her
database number is 1234. Tomorrow, it will also remember that she's 1234. And
tracking is all stored in few XML config files for easy calculation.

~~~
eevilspock
> Yeah, privacy, schmiravacy. That horse has done gone left the barn.

So you're using the slippery slope as justification and welcome sign instead
of warning. The world is all downhill from here exactly because people don't
have the integrity and courage to resist.

Also

~~~
kefka
Slippery slope? Humans already can do classification. Should we ban humans
from identifying and counting other humans?

I can hire 2 guards who can remember people by taking a photo. And then I can
have them recall who shows up. With people.

All my project does is substitute a computer for human. The only reason why we
don't do the above is because people cost a lot more. Computer software and
cycles are cheap.

And the procedure I used with my code saves a hash of the face. I cannot
generate faces from the hash, although it would be a one liner to spool a face
to the hard drive when a pic is captured. My software doesn't do that.

~~~
thwest
You see, humans have judgement, and obvious presence. I don't mind George and
Jim remembering I was at the pub on Tuesday, because they will consider who to
reveal that information to before they do. (A pub I don't think anyone would
be at if there were two guards photographing everyone). These giant piles of
databases are open for everyone.

~~~
kefka
Doesn't the business have a right to keep track of its clientèle? Obvious
legalities of underage-ness of a pub aside, I already can hire counters that
watch the security feed and assess numbers.

And also, CCTV isn't open to the public or traded around wanton. Instead, I
would argue, this data is highly confidential to the business and therefore
would guard it selfishly.

And as for the pub photographing: There has been a trend in bars in
Indianapolis to scan he barcode on the back of the drivers license to "verify
identity". What they're really doing is building up a clientèle database for
which they can do whatever with. And they are booming bars.

------
downandout
This reminds me of Motionloft. Their CEO was an idiot and ran into some legal
trouble [1] which hurt the company, but it was backed by Mark Cuban and is
still running afaik. I have thought since first learning about Motionloft that
this could be a big business but I don't understand why both companies refuse
to just sell the hardware. There have to be a ton of companies that would buy
it but don't want their very sensitive data about customer counts etc. being
transferred to a third party that could be hacked etc.

[1]
[http://techcrunch.com/2015/04/01/cuzyolo/](http://techcrunch.com/2015/04/01/cuzyolo/)

------
lmb
Soo I thought I had seen this somewhere, just with WiFi used to measure users,
turns out it comes straight from the past![0]

In the interests of science, why did you switch from WiFi signals to infra-red
door counters? Was it that you picked up passersby? (See [1] for previous
pitch, which explains it more than the archive.org website)

[0]
[https://web.archive.org/web/20140605031145/http://www.densit...](https://web.archive.org/web/20140605031145/http://www.density.io/)

[1]
[https://www.youtube.com/watch?v=yRGa9-QUDWo](https://www.youtube.com/watch?v=yRGa9-QUDWo)

------
bliti
Something like one of those points rewards cards with rfid and this could
allow a merchant to get your purchase data as you enter the premises. Then
with other rfid readers throughout the store you can pinpoint where $user
spends most time and adjust $coupon for them to incite purchase. Or maybe
multiple IR beams like this one in different parts of the store to have
traffic metrics on the floor plan. Looks very nice from the design standpoint.
It is something that will not register in the mind of the customer.

If this interests you:

This type of thing can be done at the hobby level. Since this is mostly an IR
sensor with wifi connectivity talking to an API and sending mqtt data.

~~~
eli
There are already solutions that do this using your phone's wifi:
[https://www.washingtonpost.com/blogs/the-
switch/wp/2013/10/1...](https://www.washingtonpost.com/blogs/the-
switch/wp/2013/10/19/how-stores-use-your-phones-wifi-to-track-your-shopping-
habits/)

------
darrenbuckner
Great product and great team. Congrats everyone!

------
tommccabe
How does your product compare to existing traffic solutions, like Shoppertrak?

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

------
inoks
There many similar startups over the world:

[http://sensalytics.net](http://sensalytics.net) \- Deutch project counting
people, mobile tracking and cash register data.

[http://i-counter.ru](http://i-counter.ru) \- Russian projects - uses IR
counter with 3G transmission module, so data send directly to web analytics
server without additional networking devices.

------
watty
Looks like an awesome product and hardware but the SAAS model sucks (for us).
Here's to hoping they release a LAN model for a one time fee.

------
dtertman
Your home page freezes my Firefox (33.1 on Mac) :( . Have to pound through
five or six unresponsive script warnings.

After that, pretty cool idea and nice site!

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

------
vpontis
This seems really cool! I can think of a bunch of new things to do with this
and a lot of places where I want to know how busy they are.

The one thing that really confuses me is the pricing structure. Why do you
need to pay each month? Paying $300 for one year of usage seems pretty steep.

It's service pricing but it seems like one-time service/purchase.

------
joeyespo
This looks awesome! Would love to know ahead of time how crowded my local
coffee shop is before I packed up to work there.

~~~
valarauca1
If this is the indented use case what purpose the coffee shop have to add one?
If in most cases it'll only discourage customer attendance.

To be a member of _the queue_ of an establishment can carry some of the social
status of that establishment itself. This is a primative notion yes, but
fairly ingrained culturally. As businesses often judge their _prestige_ by the
length of the queue to enter.

~~~
netfire
Too long of a queue could discourage customer attendance as well, as people
may not want to wait a long time, no matter how prestigious the business is.
In addition, a lesser-known business could use lower wait times as a
competitive advantage.

What really matters, in my opinion, is whether having a long line during
certain peak times generates more revenue for the business (by being able to
charge more, or by gaining attention due to its long queues) or whether
providing a faster and better customer experience with shorter wait times does
(and perhaps more customers during non-peak times)

Whether one is better than the other may depend completely on your business.
Also, I'm not sure this technology forces you to publish your current density
information. You could simply use the information for business intelligence
gathering and for providing promotions during non-peak times.

------
rpcope1
How do these talk with the outside world? Do you need to attach them to your
own internal WiFi?

~~~
afar
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.

------
nubela
Gorgeous web design, kudos.

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

------
ljk
Does anyone know why is this product "Show HN" while the other product
currently on the front page, Soloshot, only has a product name and slogan?

~~~
jordanmessina
I did the Show HN. The original title was "Density Platform" because we just
revealed our new sensors and the public facing API. Not sure why a mod changed
it.

------
thedogeye
There will be a big business putting these on all the entrances of a publicly-
traded casino and then tracking activity levels.

------
wehadfun
What communications protocol is it using?

~~~
jordanmessina
We're using infrared sensors to detect ingresses and egresses from locations.

~~~
valarauca1
How does the solution handle multi-ingress/egress points?

Could it be used for tracking population leaving during a fire drill? As often
this is the first question asked by first responders, "Is anyone still
inside?"

~~~
escobar
This would be a reallly cool application if PIR's were capable of counting
"horde" foot traffic, like a giant mass of people streaming out of a door
during an alarm. I don't think that something like a PIR could handle that
number of people, since it's just the single beam.

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

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talsnet
Looking forward to hearing more about it when you're ready to share

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Fudgel
Could this be done with Apple's iBeacon as well?

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jordanmessina
It can! To accomplish this there'd need to be a custom iPhone app for a
location and everyone that goes in would have to have the application
installed and have their bluetooth turned on.

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afar
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.

