Tang, J. K. T., Leung, H., Komura, T., and Shum, H. P. H. Emulating human perception of motion similarity. Comput. Animat. Virtual Worlds 19, 3-4 (2008), 211–221. [PDF]

———-

Evaluating the similarity of motions is useful for motion retrieval, motion blending, and performance analysis of dancers and athletes. Euclidean distance between corresponding joints has been widely adopted in measuring similarity of postures and hence motions. However, such a measure does not necessarily conform to the human perception of motion similarity.

In this paper, the authors propose a new similarity measure based on machine learning techniques. They make use of the results of questionnaires from subjects answering whether arbitrary pairs of motions appear similar or not. Using the relative distance between the joints as the basic features, they train the system to compute the similarity of arbitrary pair of motions. Experimental results show that our method outperforms methods based on Euclidean distance between corresponding joints.

Their method is applicable to content-based motion retrieval of human motion for large-scale database systems. It is also applicable to e-Learning systems which automatically evaluates the performance of dancers and athletes by comparing the subjects’ motions with those by experts.  

Finally, I found some time to write a short report about the inspiring talks I attended at LIFT09. Patrick Gyger presented the first talk. He is the director of the “Maison D’Ailleur” a Science-Fiction museum in Human perception-driven, similarity-based access to image databases Yverdon, Switzerland. He talked about the way futuristic ideas that were imagined by science fiction of the beginning of the century did not make it to the real future.

Future was sketched as a stylish future. What happened to these visions? Science Fiction as a genre stated at the beginning of the 20th century. Future in these early attempts was not a function but it was a style. Flying cars did exist. There were many existing prototypes produced and certified in the past. Why they did not work? It is because they were not answering a real need but only a dream desire. Other things did make it to the present: examples, the wristwatch, cybernetics. The future did not take the form it was designed. But some functions are here. We do not have an urgent need for utopias any more. We live in too much comfort in developed countries. With food, lodging… There is no way that only our material world will chage our life. We require a societal change.

Nicolas Nova, my friend and colleague back at EPFL, extended this initial flow of ideas with a talk titled: “The Recurring Failure of Holy Grail”. He talked about many products that were designed and used as examples of futuristic technology but which failed at becoming mass products. He presented three examples: 1) the videophone, 2) the intelligent fridge, and 3) location-based services. Nicolas tried to sketch possible reasons that brought to the failures of these products. He described how researcher were overoptimistic, and how they had little knowledge of similar previous attempts. He described how it is easy to get trapped in the zeitgeist of the futuristic wave surrounding an invention. Additionally, he pointed out how we often forget the development and adoption cycles that it takes for new technologies to get adopted. Finally, he pointed out the we generally have a poor understanding of “users”. I totally subscribe to Nicolas’ idea that there is a need to document failures just as we document successes.

David Rose presented a number of “Ambient Devices“, little gadget interfaces that were somewhat inspired by fictional stories. He described how fiction sometimes foreshadows innovation. He presented a number of “enchanted objects” designed around some basic fictional powers/desires: 1) to know. Example: to know the truth — invention — truth machine –> Snow white: the mirror. Therefore he presented the Single pixel browser, a sphere that changes color in relation to some information available somewhere in the internet. Its principle was that summarization is more valuable because it requires less time and attention. David presented a number of other inspiring projects like an Internet connected pills container or sensors embedded in the fabric of the home.

Lee Bryant gave a presentation titled: “The twentieth century was wrong”. His main message was that many products, campaigns, initiatives treat people like objects/mass. This is wrong. Models based on social networks, where every member contributes to the group, are much more interesting and proven to work. Let’s stick to that.

Juliana Rotich talked about citizen journalism: “Globalism, Mobiles and the Cloud”. She described how volunteers around the world can provide objective and localized news that are not controlled by mainstream media. She described the project GlobalVoices. In order for this platform to work, another project had to be started, called LINGUA translation project because English does not equate with global. She described a couple of examples of services that are extremely popular in Africa like MobInfo in Kenya. Citizen Journalists does not equate with a person with a mobile phone. They still need to have some journalistic skills.

Carlo Ratti direct the senseablecity lab at the MIT. He described a number of project that he conducted around the theme of “Future Cities”. GreenWheeil in Copenhagen is a system to enhance a bicycle system so that some of the energy accumuated while pedaling can be reused to propel the bike. Trash Track is a project aiming at tracking movements of transh in a city to improve sanitizing systems. He finally described the Digital Water Pavillon built for the expo in Zaragoza.

Anne Galloway described the core of her PhD research: Envisioning the future city. She argues that many services/ products that researchers develop should be considered as gifts to the users. Expectations, promises and hopes are things that we do: these are GIFTED opportunities, as for example sensors technologies can allow citizens to map environmental conditions, or citizens can use these data to take political action. This gift needs us to want to act as data collectors and it needs us to have the ability to make sense of the data we collect. Most of the time people do not want these gifts, hence their failures. Additionally, gifted opportunities imply also gifted risks: when active citizenship requires access to technology, people without access effectively become non-citizens.

Finally, Baba Wame talked about “how African woman have embraced dating websites in Cameroon”. He explained, in a hilarious speech, how they use this new technology to escape the difficult situations they live in and how they appropriate this technology even if they are, in most of the cases, illiterate.

Quiero un río de manzanas y sus orillas quiero ver a toda la población del mundo unida, reunida, en el acto mas simple de la tierra, mordiendo una manzana.
P. Neruda, 1951

It is not alway what you can take out of society that counts, but what you can put in.

Tim Berners-Lee

Benevenuto, F., Duarte, F., Rodrigues, T., Almeida, V. A., Almeida, J. M., and Ross, K. W. Understanding video interactions in youtube. In MM ’08: Proceeding of the 16th ACM international conference on Multimedia (New York, NY, USA, 2008), ACM, pp. 761–764. [PDF]

———–

This paper reports a number of experiments conducted to understand user behavior in a social network created essentially by video interactions. The authors crawled and analyzed interactions in YouTube finding many peculiarities of this kind of systems.

For instance, unlike other social networks that exhibit a significant degree of symmetry, the user interaction network shows a structure similar to the Web graph, where pages with high in-degree tend to be authorities and pases with high out-degree act as hubs directing users to recommended pages. This analysis is very useful to detect spammers, which might be nodes with very high out-degree.

Similarly, unlike social networks, the network in YouTube exhibit diassortive mixing, where high degree nodes preferentially connect with low degree ones and vice versa.

The authors also used a clustering coefficient (CC) to show the presence of small communities in the video-response network. Specifically, 80% of all nodes in the entire user interaction network have CC = 0, meaning that higly responsive users do not necessarily ave social links with the contributors of the videos that they are responding to. Therefore, there might not exist a sense of community among the users that receive video responsens from a responsive user.

The analysis also highlighted three kinds of anti-social behavior: a) submission of videos with a long list of misleading tags; b) posting video responses which are unrelated to the original video; and c) ranking boosting of personal video to have them highly visible.

Finally, the author used an inter-reference distance (or IRD) to characterize the user’s behavior: on the sequence of video-responses to video i, it is the total number of responses that appear between two video reponses from the same user. The author compared this metric with a manual coding of social or anti-social user and showed that the metric correctly identifies 80% of anti-social users.

“La tontería es infinitamente mas interesante que la inteligencia. La tontería no tiene límites, la integencia si”

Claude Chabrol

He who loves practice without theory is like the sailor who boards ship without a rudder and compass and never knows where he may be cast.

Leonardo da Vinci, 1452-1519

I stumbled upon this nice article of Mathew Honan where he reports his impressions on living with many location-aware applications (LBAs) continuously tracking, and communicating, his position to others. His main concerns regarded, of course, privacy. Basically, he argues that with a minimal number of datapoints it is easy to infer where a person lives or works:

On a sunny Saturday, I spotted a woman in Golden Gate Park taking a photo with a 3G iPhone. Because iPhones embed geodata into photos that users upload to Flickr or Picasa, iPhone shots can be automatically placed on a map. At home I searched the Flickr map, and score—a shot from today. I clicked through to the user’s photostream and determined it was the woman I had seen earlier. After adjusting the settings so that only her shots appeared on the map, I saw a cluster of images in one location. Clicking on them revealed photos of an apartment interior—a bedroom, a kitchen, a filthy living room. Now I know where she lives.

As these technologies are far more pervasive than what we imagine them to be, it is easy for computer illiterates to loose track of where private information might appear. Even worst, once it escapes the control of the person, it is difficult to remove it from the cyberspace:

And location info gets around. The first time I saw my home address on Facebook, I jumped—because I never posted it there. Then I realized it was because I had signed up for Whrrl. Like many other geosocial applications, Whrrl lets you cross-post to the microblogging platform Twitter. Twitter, in turn, gets piped to all sorts of other places. So when I updated my location in Whrrl, the message leaped first to Twitter and then to Facebook and FriendFeed before landing on my blog, where Google indexed it. By updating one small app on my iPhone, I had left a giant geotagged footprint across the Web.

According to Honan, the most interesting benefit of LBAs is the possibility to locate objects or services nearby when a person is on the move. Also, he mention that through these services we can increase our social appearance and perception (e.g., I am here, do you want to have a coffee?). Problem with that is the lack of proper etiquette or protocol.

This issue came up again while having dinner with a friend at Greens (37.806679 °N, 122.432131 °W), an upscale vegetarian restaurant. Of course, I thought nothing of broadcasting my location. But moments after we were seated, two other friends—Randy and Cameron—showed up, obviously expecting to join us. Randy squatted at the end of the table. Cameron stood. After a while, it became apparent that no more chairs would be coming, so they left awkwardly. I felt bad, but I hadn’t really invited them. Or had I?

Finally, Honan points out how we should not give up completely our physical context in favor of digital content. One of the biggest challenge of this field is that for this information to avoid to be invasive, creepy, or isolating.

Brody, A. B., and Gottsman, E. J. Pocket bargain finder: A handheld device for augmented commerce. In HUC ’99: Proceedings of the 1st international symposium on Handheld and Ubiquitous Computing (London, UK, 1999), Springer-Verlag, pp. 44–51. [URL]

———–

This paper presents Pocket BargainFinder, a prototype that lets the consumer browse products in the physical world, then buy them, at the best deal, in the virtual world. The main argument of the authors was that consumers want some kind of tangible contacts with goods as they shop and that shopping agent were not able to be accessed on a mobile device.

Imagine a Saturday morning visit to your neighborhood Super Bookstore. You’re enjoying your pick from the New York Times Bestseller List, with a double mocha latte and a banana walnut muffin on the side. Light classical music wafts from the overhead speakers as you sink deeper into an oversized leather chair. The book’s a great read—you’d like to buy a copy—so you slip your Internet-connected mobile phone from your pocket and scan the barcode on the book jacket, using a compact barcode reader. In moments, price quotes appear on the phone display: an online bookstore has the book for 40 per cent less than the Super Bookstore price.

The t statistic was introduced in 1908 by William Sealy Gosset, a statistician working for the Guinness brewery in Dublin,  Ireland (“Student” was his pen name). Gosset had been hired due to Claude Guinness’s innovative policy of recruiting the best graduates from Oxford and Cambridge to apply biochemistry and statistics to Guinness’ industrial processes. Gosset devised the t-test as a way to cheaply monitor the quality of beer. He published the test in Biometrika in 1908, but was forced to use a pen name by his employer, who regarded the fact that they were using statistics as a trade secret. In fact, Gosset’s identity was known to fellow statisticians.

[More on Wikipedia]