A first device determines relative position data representative of a position of one or more other user devices relative to the first device. To determine relative position data between the first device and a second device, the first device determines a distance between the first device and the second device at a plurality of timestamps. Additionally, the first device determines movement data at each timestamp from one or more device sensors. The movement data at each corresponding timestamp may reflect movement of the first device and/or the second device between a prior timestamp and the corresponding timestamp. The first device computes relative position data for the second device by combining the distance measurements and movement data over the plurality of timestamps, for instance, through a process of sensor fusion. By computing the relative position data, the first device may determine a transformation that can be used to convert between a coordinate system of the second device and the coordinate system of the first device.