Photographic memory

The Narrative clip is a wearable camera that automatically takes a picture every 30 seconds. One year and a half ago, I decided to back this ambitious Kickstarter project. I will try to explain why I did so and share my experience using the «clip» for a few weeks.

My Black Narrative Clip
My Black Narrative Clip

Forget it to better remember

The clip doesn’t have any button. You don’t «switch it on». It is designed to be worn and to automatically take pictures every 30 seconds. To stop, just put it in your pocket or face down on a table. This simple interaction design, its weight and size make the result something that you don’t have to care about. There is a clever “double tap” feature to take a picture and star it, but this is not the main use case. You just wear it, and forget about it.

An experiment

I’ve chosen to give it a try, mostly as an experiment. I am aware that having the ability to record anything I see may have an impact on my personal life, that’s what I want to experience.

I always considered that the most precious things on my computer were my personal pictures (today stored privately online). I like taking a few pictures of events. I have been storing and paying attention to them for the last 15 years. Sometimes, it happens that I visually go into the past and remember a moment with more details that I could do by myself thanks to these images.

Human memory

As Wikipedia describes it, our memory doesn’t store every moment of our life with the same level of details. While our sensory memory let us recall exact details of an item we just saw, we are not storing them and are most likely to forget them in the next minutes (for example, the color the shirt of the person sitting next to you, the exact amount you just paid at a restaurant…). Our short-term memory allows us to explicitly remember an information for a short period of time, but we are most likely to forget it later. We do not remember everything, we are explicitely and implicitely storing scenes of our life in our long-term memory. The fact that we remember a scene more than an other has, I think, many causes: attention, frequency, emotional level…

Photographic memory

The Narrative clip is a different kind of memory, it is lossless. It stores the same level of detail for every picture, every moment. This is, for me, a new kind of memory. It is useful? probably not a lot, but these kind of devices may change the way we are able to remember the past. It is like having an eternal eidetic visual memory, like this Enki Billal character whose quest is to remember the first days after his own birth in Le Sommeil du monstre.

I think being able to go back in time is priceless. Being able to live a second time a given day you experienced a long time ago is an experience that is not possible today, but that we may see tomorrow, and Narrative goes into this direction.

Technically, the pictures taken by the clip are not ideal, the camera’s field of view (70°) is really small compared to the human eye (or a GoPro) and the image sensor could really be improved for dim light. This often leads to noisy pictures, not capturing the whole scene and of a strange framing. While these are negative points and could definitively be improved in future versions, they are also a way to be later surprised of what was extracted from a moment. And the real value is in the series of pictures, that together, create a moment. Most of the time, I am not focusing on one particular taken image, I prefer reviving a moment in a time-lapse mode with the Narrative application.

Wearing it

After a few weeks of wearing the clip when I felt confortable doing it, I have more answers to my initials questions: How will people react? Will people or I behave differently? When will I wear it?

First thing, most people that are not in direct interaction with me simply don’t notice it. I think it’s because it’s very discreet, and nobody knows (yet) that these kind of device exist. People I talk directly with notice, or I try to present them the device quite early when we meet. Most of them are curious, and once I explained the principle, they don’t mind if I continue wearing it and very often ask me to send them a “best-of” of the event. I was at first wearing it all the time except in professional situations, it continued but I realise now I sometimes forget it when performing routine tasks.

A lot of data

One pictures from the Narrative clip sizes 2048×1536 and weighs around 250KB. I notice I gather around 750Mo of data per day, which are automatically uploaded and stored encrypted, after analysis, on Narrative’s servers.

What’s next

What’s next is that by storing so much information, we will need powerful personal search engines. Not only being able to search by date in a efficient UI, but also by location, by action (sitting, walking, driving…), by people (face recognition), by image elements (food, grass…). The Narrative apps are far from this and I hope they will improve their mobile apps and offer a great desktop web portal over time. But maybe it’s not their job and should just open a clean API to let other people and companies organise the content.

This powerful search is a vision, but we are not that far from it when we see the power of Google+ personal photo search for example.

Not only pictures?

This idea  goes into the broader trend of lifelogging. I already passively record my position with Google Location History, the music I listen on, log a lot of things on Foursquare and Evernote… which tagline is, by the way, «Remember Everything». That says a lot on their vision, it could have been “The best app to take notes“, but no, they see larger than this, they want to help you remember, and first step into this direction is to help you take notes.

Except for a few notes, check-ins and pictures, gathering all this data is pretty useless today. But I am confident it may have more value in the future. It will be raw resource that other services will tap to generate real customised and personal value. And this value will certainly be more than editing a movie of your life after your death like Robin Williams is doing in The Final Cut.

Cocktail dosage in martini glasses: Maths are here to help

New Year’s Eve is getting close, you’d beter be prepared. Let me share a problem I had last day when I decided to make cocktails in martini glasses. How was I suppose to dose my ingredients in such cone-shaped glasses?

cocktail in a cone-shaped glass
How to properly dose a cocktail in a cone-shaped glass?

Let’s take a first example, The Black Russian recipe is:

2/3 Vodka

1/3  Kahlúa

The problem is that you cannot apply these proportions to the heights of each liquid since the glass is not a cylinder. For a same height, the volume will not be the same, and your cocktail a failure.

Our question is:

What is the ratio between the heights of the two liquids that will make their volumes meet the recipe proportions?

What we have is two volumes vV and vK and their proportion to the total of liquid Vtotal = vV + vK:

And what we want is the ratio hV / Htotal between the height of Vodka and the total height of liquid.


Volume of a cone is ,   being the base with its radius r.

We then use Thales’ theorem to link any radius r to its corresponding height h:

By using the two last formulas in our volume ratio equation, we get:

What we demonstrated here is a kind of Thales’ theorem (Intercept theorem), but for 3D cones. We obviously have the same kind of result with surfaces of triangles. That’s interesting, that’s a result I never encountered in the past. And it doesn’t only apply to right circular cones, but to any type of cone (pyramids for example), this can be proved by computing the base B using an integral.

The answer to our initial question is then:

That’s right, to have 2/3 of vodka in volume, the height of vodka should be almost 90% of the total height. If the ratio had been 1/2, the height of the first liquid should have been 80% of the total height. It’s not that obvious to me.

Last point, if your cocktail has more than two ingredients (for example a White Russian), I would suggest to always consider cones and not bother with substractions:

1/3 Vodka

1/3  Kahlúa

1/3 Cream

Start by adding 1/3 Kahlúa (70% of total height), then add Vodka until 2/3 of volume (90% of total height) and complete with cream.

Enjoy your cocktails, and happy new year!

Hack Days

I realize I never wrote about it: In 2011, I’ve been involved in the organisation of two “hacking” events (hackathons). I will describe them and try to give some feedback about the organisation of such events.

The main goal of theses events was to gather around the spirit of Hack people who can do things (developers, designers, makers…). I’m convinced that the meaning of “hack” is misunderstood, especially in France where it’s always associated with piracy. We tend to forget that many innovations or great companies of today come from little disruptive things hacked in a garage. For these hack days, the idea is that in the end, participants have to demo their hack, no slides are accepted, only prototypes!

Hack Le Camping

(June 24-25 2011)

logo for Hack Le Camping, designed by myself.

This first one came from an idea we had at Le Camping, the parisian startup accelerator were I built Beansight. I took the lead in the organization.

One of the goal was to let the startups from Le Camping open their APIs for the first time to developers.

The event was located at Le Camping, which is usually a place where 12 startups work everyday. So the place was not an issue and could welcome 80 guests.

With the help of others, we gathered two main sponsors. The deal was to let them promote their services before the event and be present on the printed materials, in exchange of €1000 each. This budget covered the food (3 meals) and also allowed us to print t-shirts for every participant. Because we didn’t find a great prize that could fit either a single hacker or a whole team, we decided to simply offer a prize of €500.

A hundred people registered to the event, and in the end around 40 hackers showed up for the event. I did not expect such a large difference, I think it’s due to the fact that the event was free of charge, a lot of people registered and never showed up later.

Participants hacking in Le Camping

The event went very well, the 24 hours were very intense for the participants. We added soon after the kick-off a stand up session for every project to explain what they were working on to the others.
In the end 10 projects were demoed. The overall winner was a team from Moodstocks. They created a fast-paced scavenger hunt mixing real time technologies from Dabla and image recognition: a player selects an object to look for, the first from the others to scan it with his phones takes the lead.

If you want to learn more about the event, here are the schedule of the event, the slides of my intro talk and a list of the hacks.

Hack Day Paris

(November 4-6, 2011)

Hack Day Paris logo, designed by Simon from Joshfire.

Soon after, I met with Skylar and Sylvain and we started discussing about a larger event.

The vision was to organize a large independent hack day in Paris, something that had never been done before. We targeted 150 hackers and wanted to gather a jury of renowned and respectful people. We did not wanted to impose a theme, but preferred to reward the “most brilliant” hack. We wanted people to work on what they liked, to produce something awesome.

We soon decided that tickets would be €10, not to make money from it, but to make sure that people registering were people really willing to come. In the end, around 140 hackers showed up. I think our strategy worked fine.

At first our main concerns were the place and communication. People from the co-working space La Ruche liked the project and its philosophy, so more than a place, they joined the project and helped us organize the event. We never could have done it without them. Communication was done by reaching all our networks (Paris Hackers, the startup ecosystem, schools…)

We gathered around €9 000 from sponsors and entries. This allowed us to provide quality food for everyone all along the 40 hours. We printed badges and rented additional Wifi.

Around a month before the event, a lot of effort had to be put into logistics: we had to make sure every people involved agreed on the schedule and the use of the places. Because many were involved, this was not an easy task at all.

The event went very well, as usual, as an organizer, you spend your time handling little issues here and there, making sure everything runs smoothly for the participants. We did shifts so that at any time during the 40 hours, one of the 3 organizers was awoken.

Demo time, in Le Comptoir Général, a bar next to La Ruche.

We had great feedback concerning the  location: La Ruche is not a regular place for such event, it’s made of little rooms, with outstanding decorations. This had a great impact on the spirit of the event.

Around 40 projects were demoed at the end the sunday afternoon. Here are some remarquable examples: a real time chess game (Ninja Chess), a place to give old things (Freesbee), a musical keyboard using balloons , a wine suggestion service (Wine Combinator)…
Once again, the grand prize was €1500 for the best team. Side prizes were organized by sponsors. The winners are a team who built a music box that links objects to music in the cloud. I will blog about it later.

For more info, visit the official website, have a look to the pictures of the event on the facebook page.

For sure, I will be involed in other hack days in the future. And I hope this article can help the ones of you who want to launch such events, feel free to contact me.

Every team needs StatusNet

I’m sure you know about twitter. If you use it, you read and share links, ideas and statuses… with everyone.
Now imagine the same tool, but restricted to your team. This is StatusNet. (and it’s even much more than this actually)

Private timeline

At Beansight, we’ve been using StatusNet since the beginning. Examples: You start working on something? Take 3 seconds to post it on your StatusNet. You spotted an interesting link? Share it with your team on StatusNet. You’ll be late for the meeting? StatusNet. You’ve got a problem? StatusNet.
If it is well used, it’s like sharing the same mind. You are aware of what the others are doing or thinking and you can reply to them in real time. Isn’t this awesome when you work in an agile environment?

A snapshot of the Beansight timeline

Did I mentioned it costs nothing ? You can start using it privately with your team for free at (iPhone, Android or desktop app included)

Of course, we keep using e-mails for structured threads.

I know there are some other tools, and they may be better at doing this (Wedoist, Yammer…). So here comes the second part of this post:


To be more precise, StatusNet is an open source microblogging platform. This means that you can deploy it on your own servers without having to rely on a particular service provider. It is branded under your name. And you own your data. Trust me, this is something large companies are looking for (A startuper thinks it’s Ok to use Google Apps for work, now try to explain this to a big company).

StatusNet can be federated, which means that public nodes can talk to each other. They all create a global and distributed network. Moreover, it uses an open protocol. You know, the same way it works for e-mails, where you can talk to someone who is not necessarily using the same provider than you. We tend to forget how important it is for innovation to keep the pipes opened.

Public microblogging: twitter and distributed StatusNet

I think open procotols matter. Can’t you see a problem in the previous image? Haven’t you learned that relying on one ressource is dangerous? Apparently many don’t see the issue and even try to build a business upon this closed API.

You can follow me (@steren) on, a very popular public instance of StatusNet.

Last precision: Google Buzz is also promoting open protocols. Unfortunately, they are different from StatusNet. I hope these two systems will become compatible in a near future. Edit: Evan (StatusNet creator), tells us in the comments that you can already follow a Buzz user with StatusNet and that they are working together to support interoperability.

What's next?

In a couple of days, my job at Dassault Systèmes will come to an end. I finally took the decision to leave the company to entirely focus on personal projects.

I spent 6 months as an intern doing technological research: I developed a prototype for interactive painting and sculpting on 3D models. I learned a lot from research papers and from my mentor, Marc Helbling. I got more familiar with the concepts behind 3D edition software.

Then I joined the SwYm team as an employee for a year. SwYm is social web for companies, it is an online product aiming at changing the one-way relation companies have with their customers and employees. I was doing various front-end work, I lead the Wiki project and was responsible for Search related functionalities (and thus could more recently use Exalead technology). We were working in a very flexible environment comparing to other teams. Technologically speaking, the website used Javascript intensively for its dynamic layout, I learned a lot about this.

Unfortunately, I couldn’t find motivation in my every day work, it’s hard to explain why but mostly because I didn’t share all the decisions. I had too much ideas for other projects in mind. I took the decision to leave the company and come back to a more uncertain life.

In the next months, I will focus on personal projects: websites, mobile apps, art… one thing at a time (because I suck at multi-tasking). I will blog my updates very regularly at (blog coming soon) and also post results here.

You will learn more on these projects very soon. I plan to adopt a very open working attitude, and I rely on you, my followers, my readers, to give me advice, feedback, ideas or even to join me. If you are curious, I invite you to subscribe to my newsletter or to connect with me on the Internet.

If one project goes well, this adventure may lead to the creation of a company. But one thing is certain, for me, being entrepreneur is not having a twitter account and hacking on a website.

Improv and beyond

I’ve been practicing improvisational theater for more than three years now. It’s a hobby for me, and of course I don’t have the tenth of the knowledge and talent of my original teachers from Et Compagnie. But I will try to describe in this post what improv means to me.

As you may guess, it’s pleasant to have fun on stage entertaining the public, it’s pleasant to invent spontaneous stories while acting unpredictable characters. All this is true.

My team and I on stage, photo by Maxime Storn (

But improv is so much more and it has faces I think many people don’t even think about. For me improv means to

  • listen to the others,
  • think fast,
  • trust the team and be able to rely on them,
  • be inspired, have imagination and get ideas,
  • remember and take into account what has been said and settled before,
  • build uppon this and never destroy it,
  • listen and accept new things brought by others,
  • express clearly, be understood and transmit ideas efficiently,
  • assume failure and suckiness,
  • not be affraid by an uncertain and unpredictable future.

All this are things improvisers work on when they train. When correctly applied, they facilitate and make everything run well.

I encourage you to consider it next time you assist an improvisational theater show. And of course, I encourage you to give it a try. Finally, you may guess that all these principles can easily be extrapolated in real life.