Power switching time-of-flight sensor for estimating three-dimensional positions of a plurality of keypoints along a target object

A wearable device comprising:

• left and right eyepieces;
• left and right projectors optically linked to the left and right eyepieces;
• and
• a time-of-flight sensor comprising:
• an illumination unit configured to transmit first light pulses to illuminate a target object in accordance with a light synchronization signal;
• a sensor unit configured to receive second light pulses in a field of view in accordance with a shutter synchronization signal, wherein the time-of-flight sensor is configured to perform a depth measurement based on the second light pulses received by the sensor unit;
• and
• a timing generator configured to generate the light synchronization signal to control the illumination unit and the shutter synchronization signal to control the sensor unit to cause the time-of-flight sensor to switch between operating in a low power mode and operating in a high accuracy mode based on an activation condition;
• wherein operating in the low power mode comprises estimating three-dimensional (3D) positions of a plurality of keypoints along the target object based on a previously captured depth map and a currently captured amplitude map of the target object;
• wherein operating in the high accuracy mode comprises computing the 3D positions of the plurality of keypoints based on a currently captured depth map of the target object.