A system comprising: - an indoor localisation system to localise a tracked entity in an indoor environment and to output an indoor location data stream comprising indoor location data representing locations assumed by the tracked entity in the indoor environment; and - an analytics computing system designed to receive and process the indoor location data stream from the indoor localisation system to compute entity-related analytics; characterised in that the analytics computing system is designed to: - identify in the indoor location data stream one or more sessions, each representing a corresponding period during which a tracked entity carries out an associated activity in the indoor environment, based on an indoor environment model specifying one or more session open/close rules, - compute, for one or more identified sessions, associated track data representing a track travelled by the tracked entity in the indoor environment during an identified session, based on the indoor location data stream, and - compute entity-related analytics based on the track data; wherein the indoor localization system is designed to output a raw indoor location data stream, and wherein either the indoor localization system or the analytics computing system further comprises data cleaning the raw indoor location data stream based on the indoor environment model to output a clean indoor location data stream for further processing; wherein data cleaning comprises: - processing the raw indoor location data stream to identify an indoor environment in which the associated tracked entity is moving into; and - responsively fetch a corresponding indoor environment model out from an indoor environment model database; and one or more of the following: - augmenting indoor location data in the raw indoor location data stream environment-specific metadata from the indoor environment model; and - filtering out possible specific indoor location data that should not be used for tracking purposes based on the indoor environment model. - an indoor localisation system to localise a tracked entity in an indoor environment and to output an indoor location data stream comprising indoor location data representing locations assumed by the tracked entity in the indoor environment; and - an analytics computing system designed to receive and process the indoor location data stream from the indoor localisation system to compute entity-related analytics; characterised in that the analytics computing system is designed to: - identify in the indoor location data stream one or more sessions, each representing a corresponding period during which a tracked entity carries out an associated activity in the indoor environment, based on an indoor environment model specifying one or more session open/close rules, - compute, for one or more identified sessions, associated track data representing a track travelled by the tracked entity in the indoor environment during an identified session, based on the indoor location data stream, and - compute entity-related analytics based on the track data; wherein the indoor localization system is designed to output a raw indoor location data stream, and wherein either the indoor localization system or the analytics computing system further comprises data cleaning the raw indoor location data stream based on the indoor environment model to output a clean indoor location data stream for further processing; wherein data cleaning comprises: - processing the raw indoor location data stream to identify an indoor environment in which the associated tracked entity is moving into; and - responsively fetch a corresponding indoor environment model out from an indoor environment model database; and one or more of the following: - augmenting indoor location data in the raw indoor location data stream environment-specific metadata from the indoor environment model; and - filtering out possible specific indoor location data that should not be used for tracking purposes based on the indoor environment model. - identify in the indoor location data stream one or more sessions, each representing a corresponding period during which a tracked entity carries out an associated activity in the indoor environment, based on an indoor environment model specifying one or more session open/close rules, - compute, for one or more identified sessions, associated track data representing a track travelled by the tracked entity in the indoor environment during an identified session, based on the indoor location data stream, and - compute entity-related analytics based on the track data; wherein the indoor localization system is designed to output a raw indoor location data stream, and wherein either the indoor localization system or the analytics computing system further comprises data cleaning the raw indoor location data stream based on the indoor environment model to output a clean indoor location data stream for further processing; - processing the raw indoor location data stream to identify an indoor environment in which the associated tracked entity is moving into; and - responsively fetch a corresponding indoor environment model out from an indoor environment model database; and one or more of the following: - augmenting indoor location data in the raw indoor location data stream environment-specific metadata from the indoor environment model; and - filtering out possible specific indoor location data that should not be used for tracking purposes based on the indoor environment model.