A location-based service includes detecting the relative motion of an on-site resource, detecting the absolute position of the on-site resource, and tracking the position of the on-site resource. The position is tracked by deriving a deduced position based on the detected relative motion and adjusting the deduced position as a function of and in response to the detected absolute position. According to one embodiment, the on-site resource can be a shopping cart and the tracking includes recording a travel pattern of the shopping cart as it moves through a site floor plan such that the travel pattern is reproducible. Preferably, the recorded travel pattern includes travel patterns within an aisle in the site floor plan such that the recorded patterns include travel along the length of the aisle and travel having components which are perpendicular to the length of the aisle.