[u' @article{lopez_de_ipina_trip:_2002, title = {{TRIP}: {A} {Low}-{Cost} {Vision}-{Based} {Location} {System} for {Ubiquitous} {Computing}}, volume = {6}, issn = {1617-4909}, shorttitle = {{TRIP}}, url = {http://dx.doi.org/10.1007/s007790200020}, doi = {10.1007/s007790200020}, abstract = {Sentient Computing provides computers with perception so that they can react and provide assistance to user activities. Physical spaces are made sentient when they are wired with networks of sensors capturing context data, which is communicated to computing devices spread through the environment. These devices interpret the information provided and react by performing the actions expected by the user. Among the types of context information provided by sensors, location has proven to be especially useful. Since location is an important context that changes whenever the user moves, a reliable location-tracking system is critical to many sentient applications. However, the sensor technologies used in indoor location tracking are expensive and complex to deploy, configure and maintain. These factors have prevented a wider adoption of Sentient Computing in our living and working spaces. This paper presents TRIP, a low-cost and easily deployable vision-based sensor technology addressing these issues. TRIP employs off-the-shelf hardware (low-cost CCD cameras and PCs) and printable 2-D circular markers for entity identification and location. The usability of TRIP is illustrated through the implementation of several sentient applications.}, number = {3}, urldate = {2014-11-20TZ}, journal = {Personal Ubiquitous Comput.}, author = {L\xf3pez de Ipi\xf1a, Diego and Mendon\xe7a, Paulo R. S. and Hopper, Andy}, month = jan, year = {2002}, note = {00000}, keywords = {bidimensional codes, image processing, location systems}, pages = {206--219} }']