1. A method for estimating respiration rate of a subject of interest being monitored for respiratory function in a non-contact, remote sensing environment, the method comprising: receiving a video of a target region of a body of a subject of interest being monitored for respiratory function; processing said video images to reconstruct 3D depth information of the scene and estimate 3D time-series data from said 3D depth information for said target region; and estimating said subject's respiration rate from said 3D time-series data.