A wearable sensing device for gesture-based control of a computing device (116, 118, 120), the wearable sensing device comprising: a camera (304, 400) to capture images of an articulated part of a body comprising a hand of a wearer of the sensing device; a tracking module arranged to use the captured images to track a 3D articulated model of the articulated body part; and a communication interface arranged to send the tracked 3D articulated model to the computing device (116, 118, 120) in order to control the computing device (116, 118, 120) according to 3D articulation of the articulated body part; characterized in that the wearable sensing device comprises: a structured illumination source (306, 406) positioned at a specified distance from the camera to illuminate the articulated body part with a known structured illumination pattern; and at least one diffuse illumination source (302, 402) to illuminate the articulated body part with diffuse illumination; and wherein the captured images comprise structured light images comprising images of the articulated body part illuminated with the structured illumination pattern and diffuse images comprising images of the articulated body part illuminated with the diffuse illumination source (302, 402); and wherein the tracking module is arranged to calculate 3D positions (514, 716, 1516) of segments of the structured light pattern of the structured light images, calculate digit tip locations (522, 1518) from the diffuse images and input the digit tip locations and the 3D positions to an inverse kinematics process to track the 3D articulated model. a camera (304, 400) to capture images of an articulated part of a body comprising a hand of a wearer of the sensing device; a tracking module arranged to use the captured images to track a 3D articulated model of the articulated body part; and a communication interface arranged to send the tracked 3D articulated model to the computing device (116, 118, 120) in order to control the computing device (116, 118, 120) according to 3D articulation of the articulated body part; characterized in that the wearable sensing device comprises: a structured illumination source (306, 406) positioned at a specified distance from the camera to illuminate the articulated body part with a known structured illumination pattern; and at least one diffuse illumination source (302, 402) to illuminate the articulated body part with diffuse illumination; and wherein the captured images comprise structured light images comprising images of the articulated body part illuminated with the structured illumination pattern and diffuse images comprising images of the articulated body part illuminated with the diffuse illumination source (302, 402); and wherein the tracking module is arranged to calculate 3D positions (514, 716, 1516) of segments of the structured light pattern of the structured light images, calculate digit tip locations (522, 1518) from the diffuse images and input the digit tip locations and the 3D positions to an inverse kinematics process to track the 3D articulated model. a structured illumination source (306, 406) positioned at a specified distance from the camera to illuminate the articulated body part with a known structured illumination pattern; and at least one diffuse illumination source (302, 402) to illuminate the articulated body part with diffuse illumination; and wherein the captured images comprise structured light images comprising images of the articulated body part illuminated with the structured illumination pattern and diffuse images comprising images of the articulated body part illuminated with the diffuse illumination source (302, 402); and wherein the tracking module is arranged to calculate 3D positions (514, 716, 1516) of segments of the structured light pattern of the structured light images, calculate digit tip locations (522, 1518) from the diffuse images and input the digit tip locations and the 3D positions to an inverse kinematics process to track the 3D articulated model.