A computer-implemented method to identify positions of fingers of a hand, the positions being used to render a virtual hand to be displayed in a head mounted display when presenting a virtual environment in the HMD, comprising: capturing images of a first hand of a user and of a plurality of light emitters (LES2, LES21, LES22, LES 23) configured to emit light and forming part of a first wearable device worn around a wrist of the first hand of the user, using a plurality of cameras (C1, C11, C12, C13) that are part of a second wearable device, the second wearable device being worn around a wrist of a second hand of the user, the plurality of cameras of the second wearable device being disposed around the second wearable device so that the plurality of cameras are distributed around the wrist of the second hand, wherein at least one of the plurality of cameras faces the first hand; repeating capturing of additional images of the first hand and of the emitted light, the images and the additional images captured to produce a stream of captured image data during a session of presenting the virtual environment in the HMD; and sending the stream of captured image data to a computing device that is interfaced with the HMD, the computing device configured to identify from the captured image data changes in positions of the fingers of the first hand for rendering the virtual hand in the HMD corresponding to the changes in the positions of the fingers of the first hand, wherein the plurality of light emitters are distributed around the first wearable device and are configured to emit light of respectively different characteristics; and wherein the computing device is configured to identify, based on a correspondence between the characteristics of light detected in the captured image data and the orientation of the first wearable device, an orientation in which the first hand faces at least on of the cameras that captured the image data. capturing images of a first hand of a user and of a plurality of light emitters (LES2, LES21, LES22, LES 23) configured to emit light and forming part of a first wearable device worn around a wrist of the first hand of the user, using a plurality of cameras (C1, C11, C12, C13) that are part of a second wearable device, the second wearable device being worn around a wrist of a second hand of the user, the plurality of cameras of the second wearable device being disposed around the second wearable device so that the plurality of cameras are distributed around the wrist of the second hand, wherein at least one of the plurality of cameras faces the first hand; repeating capturing of additional images of the first hand and of the emitted light, the images and the additional images captured to produce a stream of captured image data during a session of presenting the virtual environment in the HMD; and sending the stream of captured image data to a computing device that is interfaced with the HMD, the computing device configured to identify from the captured image data changes in positions of the fingers of the first hand for rendering the virtual hand in the HMD corresponding to the changes in the positions of the fingers of the first hand, wherein the plurality of light emitters are distributed around the first wearable device and are configured to emit light of respectively different characteristics; and wherein the computing device is configured to identify, based on a correspondence between the characteristics of light detected in the captured image data and the orientation of the first wearable device, an orientation in which the first hand faces at least on of the cameras that captured the image data.