1. A method comprising: providing a user interface for display on a sampling device, the user interface comprising a map of a venue, the venue comprising a space accessible by a pedestrian and one or more constraints of movement of the pedestrian in the space; estimating a set of locations while the sampling device moves in the venue; determining a motion path of the sampling device in the venue, the motion path starting at a starting location in the venue and ending at an estimated current location of the sampling device, wherein the estimated current location is determined using readings from one or more motion sensors of the sampling device; overlaying a representation of the motion path on the map, including animating an end point of the motion path and displaying an anchor on the motion path when an estimated moving direction of the sampling device changes; recording environmental readings by one or more signal sensors of the sampling device; adjusting the motion path on the map in response to a user input moving the anchor, the adjusted motion path connecting the starting location and the moved anchor; tagging the environmental readings with waypoints on the adjusted motion path; and submitting the tagged environmental readings to a server as survey data for determining a location fingerprint of the venue, the location fingerprint usable by a user device to estimate a location of the user device in the venue.