1. A depth imaging system, comprising: a depth camera input to receive a depth map representing an observed scene optically imaged by a depth camera, the depth map including a depth value for each pixel in a two-dimensional matrix of pixels, each depth value representing a distance from the depth camera to a surface that is optically imaged by the depth camera for a corresponding pixel in the two-dimensional matrix of pixels, the depth camera including an infrared transmitter and an infrared image sensor configured to measure a time-of-flight of infrared light transmitted from the infrared transmitter and reflected back to the infrared image sensor for each pixel in the two-dimensional matrix of pixels, the depth camera further comprising visible light imaging sensors configured to measure visible ambient light reflected to the visible light imaging sensors for each pixel in the two dimensional matrix of pixels; a tag identification module to identify a 3D tag imaged by the depth camera and represented in the depth map, the 3D tag comprising one or more depth features, each of the one or more depth features comprising one or more characteristics recognizable by the depth camera; and a tag decoding module to translate the one or more depth features into machine-readable data.