Abstract: A method for generating an indoor environment model of a building. The method comprises forming a transmitter location model for defining positions of transmitters in said building using gathered information for establishing transmitter locations. The method further comprises receiving signal strength indicative measurements determined for a number of transmitters using at least one electronic communications device wherein the signal strength indicative measurements are based on a signal which has varying signal propagation characteristics in the indoor environment The signal strength indicative measurements are acquired from a number of known locations in the building, identifying discrepancies of signal transmittance in said indoor environment based on said signal strength indicative measurements in relation to said transmitter location model.

Abstract: A method for tracking objects in a scene being viewed by a sequence of digital images comprises: separating a region of interest in the digital images into a plurality of spatially smaller, overlapping modules, and defining a hidden Markov model for each module. The method further comprises observing detections of positions of possible objects at different times, considering a set of states at a point of time (t1) such that the set of states comprises a state having a global optimum probability, and backtracking through the sequence of digital images for each hidden Markov model to shrink the set of states that are possible for earlier parts of the sequence of digital images, such that a single optimal state is found for an earlier point of time (t2<t1), whereby tracks of detected objects through the scene are determined up to the earlier point of time (t2).