: Sentient Computing gives perception to computing systems so that they can detect, interpret and respond to changing aspects of users' context. The location attribute of a user's context is of special interest because it makes human-computer interactions more natural. This explains the appearance in the last years of several sophisticated indoor location technologies to track user whereabouts. However, these positioning systems are costly and difficult to deploy, configure and operate, having prevented a wider adoption of the Sentient Computing paradigm. This paper describes a novel vision-based software location system, known as TRIP, whose low-cost, off-the-shelf hardware requirements and easy deployment features overcome other systems' limitations. Nevertheless, in order to foster the deployment of sentient spaces, bringing services to users wherever they are or move to, a location system must also be accompanied by middleware to facilitate user-bound software servic...