1. A depth camera system comprising: a plurality of cameras with at least partially overlapping field of views; a plurality of sources, each arranged to project a structured light pattern; and a controller arranged to control a plurality of source-camera pairs to reduce the interference between projected structured light patterns and to receive signals from each of the cameras for use in depth determination, controlling a plurality of source-camera pairs comprising controlling a plurality of sources and a plurality of cameras, the controller being further arranged to control the movement of a source-camera pair relative to other source-camera pairs such that the structured light pattern projected by the source is fixed relative to the camera.