GlobalSat BT338

I got myself a GlobalSat BT338 with a built-in SiRFIII to make some experiments over the summer including:

• GSM antenna mapping for GSM positioning
• Calculate my GPS availability in my daily urban life
• Calculate my GPS availability while I am mobile
• Calculate the accuracy of the GPS signal while I am mobile
• In train tests for the locosound project

My GPS trace in the city

The lovely urban canyons of my neighborood (I walked on a perfectly straight street)

Straight line at the open sky, old seeport.

Dust Network for Real-time Predictive Traffic Information

The San Jose Mercury News has an article on Inrix which is a company that offers US nationwide traffic information based on the GPS data collected by third-party companies fleet vehicles rather than road sensors. They claim to track more that 500,000 probe floating cars.

Relation to my thesis: Inrix mentions that “since the accuracy, timeliness and thoroughness of traffic data is the key to its usefulness”

Learning Significant Locations and Predicting User Movement with GPS

Ashbrook, D. 2002. Learning Significant Locations and Predicting User Movement with GPS. In Proceedings of the 6th IEEE international Symposium on Wearable Computers (October 07 – 10, 2002). ISWC. IEEE Computer Society, Washington, DC, 101.

This paper investigates the creation of a predictive model of the user’s future movements, based on the clustering of GPS data and their incorporation into a Markov model that can be consulted for use with a variety of location-aware applications.

The contribution of this authors lies in the determination of users’ significant places (clustering) and predicting the next move (Markov model). One limitation of this approach is that changes in schedule may take a long time to be reflected in the model.

They mention problems in using GPS:

While in many respects GPS is an ideal sensor, some problems were encountered. Although Selective Availability has been turned off, the accuracy of our GPS receiver was 15 meters; this means that the same physical location will have a different GPS coordinate from day to day.

Relation to my thesis: In their litterature review, they mention some methods for inferring location based on GPS traces (start and end points of trips, building detection) that are close to the issues of a project I am involved in:

In their investigations of automatic travel diaries [16], Wolf et. al. used stopping time to mark the starting and ending points of trips. In their work on the comMotion system [10], Marmasse and Schmandt used loss of GPS signals to detect buildings. When the GPS signal was lost and then later re–acquired within a certain radius, comMotion considered this to be indicative of a building. This approach avoided false detection of buildings when passing through urban canyons or suffering from hardware issues such as battery loss.

[10] Natalia Marmasse and Chris Schmandt. Location–aware information delivery with ComMotion. In HUC, pages 157–171, 2000.

[16] Jean Wolf, Randall Guensler, and William Bachman. Elimination of the travel diary: An experiment to derive trip purpose from GPS travel data. In Notes from Transportation Research Board, 80th annual meeting, Washington, D.C., 2001.

This paper does not mention the many issues the prediction and inferences could create on the user level. However, their method could be interesting for post-game analysis of users intentions in CatchBob!

Naive Geography

Egenhofer, M.J. and Mark, D.M. Naive Geography. in Frank, A.U. and Kuhn, W. eds. Spatial Information Theory: A Theoretical Basis for GIS, Springer-Verlag, Berlin, 1995, 115.

A paper about the commen-sense way people infer information about geographic space and time. It defins the notion and concepts of Naive Geography. Naive Geography is the body of knowledge that people have about the surrounding geographic world. The authors focus on common-sense reasoning about geographic space and time, also called geographic reasoning. This is not to be confused with fuzzy reasoning, which is frequently applied to dealing with imprecise information.

People explore geographic space by navigating in it, and they conceptualize it from multiple views, which are mentally put together like a jigsaw puzzle. Therefore Naive geographic reasoning may actually contain “error” and will occasionally be inconsistent. The aim of the authors is to incorporate people’s concepts about space and time to mimic human thinking.

The framework for developing Naive Geography consists of two different research methodologies:

• The development of formalism of naive geographic models fro particualr tasks or sub-problems so that programmers can implement simulations on computers
• testing and analyzing of formal models to assess how closely the formalizations match human performance.

Examples of Naive Geography are:

• The earth is flat: Trans-Atlantic air travelers often ask why the flight path goes all the way up over Greenland, rather than going straight across
• Geographic information is frequently incomplete: people complete the information intelligently or by applying default rules, frequently based on common sense
• Topoloy matter, metric refines
• Distances are asymetric: in naive geograph space, this premise is frequently violated. Distance are not only thought of a lengths of paths on the Earth’s surface, but frequently seen as a measure for how long it takes to get from one place to another

Relation to my thesis: 2 interesting concepts are geographical reasoning and fuzzy reasoning. In the first case, our reasoning of space my be contrary to objective observations made by sensor in the real, physical world. I suppose the second could be applied to our reasoning with bad geospatial information. More on that isn L. A. Zadeh, “Fuzzy Logic and its application to approximate reasoning,” Information Processing 74, pp. 591–594, 1974. Other related concept is geospatial semantics, that is the study of how humans perceive geographical concepts in their everyday life, and how to exploit this understanding to create useful computing systems to increase our productivity

Incorporating user’s “naive” concept about space and time into location-aware system is an interesting underlying issue. A design goal could be to deal with (or supporting?) user’s naive geographical knowledge in location-aware systems in case of incomplete geographic information.

GSM Location Project

Similar to CellSpotting and Place Lab, GSM Location offers an application (Nokia Python, not Symbian native) for Symbian phones and an online database to map GSM fingerprints with GPS traces. The collected data are then used to do GSM-based positioning.

Relation to my thesis: Stumbled on this by chance. Not revolutionary, but provides an easy and open framework to do GSM-based positioning for specific areas.

Where is Where 2.0?

CNet’s Rafe Needleman reports in “Toronto or San Jose: where am I, anyway?” a nice example of badly inferred geo data at the… Where 2.0 conference.

I’m at the Where 2.0 conference in San Jose. Unfortunately, the Loki location-finding software on my laptop, which I raved about in a previous blog post, thinks I’m in Toronto. Probably the conference team picked up its Wi-Fi access points from an office or event in Toronto and shipped them down here. At any rate, it’s ironic, given the topic of the conference, but more importantly than that, for a few moments, Google thought I was in Canada and sent me to the Canadian version of the site (www.google.ca) when I tried to search. It was no big deal, but it shows you how location data applies to things you don’t always think of as location related. And the potential downsides to poor location data can be serious. Imagine if I had some emergency-response product that thought I was in Toronto instead of San Jose–or if I was on a VoIP phone that was registered to a different location, and then I dialed 911.

He then continues by mentioning the OpenStreetMap project as a potential answer to such issues:

the more people report where they are and where they’ve been, the more accurate maps and location-finding data will be available for everybody.

While the “wisdom of the crowd” can create improved geospatial data, it surely can also create errors and ambiguities.

Finally Suzanne Axtell reveals the source of the problem:

we’ve looked into this some more and found that the Fairmont Hotel IP block is registered in Toronto Canada. All our traffic uses the Fairmont IP.” There it is then.

Note Plazes often takes minutes before updating my location… that’s an example of location timeliness that can be the source of spatial uncertainty.

Relation to my thesis: Bad or irregular location quality is an issue that is not often takled by location-aware applications. These systems often rely on the user to notice the error and act upton it.

Light Ethnography on Taxi Driver's use of GPS Navigation Systems

Barcelona taxi drivers invest in GPS navigation systems. In my trip from and to the airport, I enjoy doing some very light ethnography on their usage of this technology. I observed and talked with 4 taxi drivers

Adoption
The very experience driver (30 years of experience!) said it he knew his job enough without relying on a system. Besides, he knows the real places of interest that are not part of a navigation system (e.g. private club for lonely businessmen or tourists). In case of real problem he uses maps contained in 2 books with index of the streets

Use coverage
It seems that they mainly used the system outside of the city center, because:

• they have enough experience to know the city center
• the drivers are aware of the GPS problems in dense urban area,
• most importantly, they are bothered by the inaccurate driving directions. The driver plans the trip with experience and contextual information in mind (e.g. time of the day, traffic flow). The driver do not hesitate in contradicting the system “Look this is wrong, my road is better”. One driver is used to disactivate the driving direction, but keeps the location awareness.

However, the drivers are enthusiast about using the features of their navigation system in the suburbs and villages. “It changed my life” one said. Mainly because:

• they used to get lost in unknown area
• they receive bigger tips for being faster!
• they can now answer the “do you know any hotel” question in unknown areas.
• they can answer to request such as “could you stop at a pharmacy on the way”
• they get out of unknown place the fastest way

Uncertainty
Since the drivers switch off the navigation system within the city, they do not experience big problem due to positioning. However, their experience make them overrule the suggested roads. Moreover they mention cases of getting lost because the destination was not on the map. On said “in that case I use my cell phone to call the destination (e.g. hotel, meeting place, training center) and get driving directions. One driver had his system notifying (with a strong thick siren) all the proximate fixed radars. It proved to be really annoying in the city because of the many false alarms generated by radars on proximate streets that are not part of the path. However, the driver seems to create an awareness of the radars: “look on that street (pointing to a parallel street), in that direction (pointing to the reverse direction) there are 3 one after the other… Two is for the speed, another for the belt”.

System configuration
A driver had to stop to program the destination, the same way he would have looked on a map.

System update
One driver relied on his daughter to update his system: “I used to own an Amstrad, now things are going to fast”. Another mentioned p2p as the source of updates: “do you know eMule?”

Relation to my thesis: In the future I should try to focus more on the aspects of uncertainty that GPS navigation system reduced and increased.

Machines Inherently Constructed by Taking the User into Account

Thoughts from my doctoral school course on interactive multimedia systems:

On my work on spatial uncertainty, I should think beyond design strategies for the interface (the interface being only a filter). My work could be more original if I consider how to design systems that inherently take the user into account. The location system may not only express its confidence but act on upon it depending on the user’s expecations. Moreover, a location algorithm or location update protocol could be built on a user representation and fed by dynamic user contextual values.

You Are Here, a Viseral Surveillance System Experience

You Are Here tracks and displays the paths of visitors traveling through a large public space. Its goal is to provides an understanding of surveillance systems’ capabilities and a visual representation of information that is normally only accessible as dry statistics.

The overhead tracking is accomplished with an array of six networked firewire cameras:

Relation to my thesis: Impressive implementation of a real-world camera-based location system. Its precision needs a very controlled environment. I focus more on uncontrolled environments in which no specific infrastructure needs to be setup.

Géocontrôle Parental

Reportage de Nouvo sur 2 systèmes de géolocalisation pour surveiller les enfants (géocontrôle parental): Le téléphone portable surveille vos enfants.

OOTAY offre une solution basée sur le GSM. On scénario affligeant nous montre un père maladif harcelant sont fils pour vérifier s’il se trouve bien où il devrait être. Le père admet tout de même des problèmes de précision et erreurs… 1 fois sur 2. Un adolescent suggère plutôt naturellemen un system explicite de géolocalisation.

Geogeny va offrir un système de géolocalisation GPS d’urgence pour les parents anxieux. Par contre, les parents devront signer une charte ethique les engageant à respecter la vie privée de l’enfant.

Relation to my thesis: Certaines problématiques des systèmes de géolocalisation apparaissent dans le reportage. Quand offrir et utliser les informations (urgence, activiation, desactivation, explicite, implicite), la qualité de l’information et la manière de la présenter à l’utilisateur (Ootay offre une carte avec un cercle évaluant la précision)