Contactless measurement of respiratory volumes: A calibration free method based on depth information

Measurements of respiratory volumes involve a great deal of effort, either by immobile equipment such as bodyplethysmography or by consumables as with spirometers. Contactless measurement methods can remedy this situation. In this paper, a depth camera is used to generate a contactless respiratory signal. A region of interest is placed over the subject's upper body and the distance-time curve of respiratory motion is recorded. Via selected signal features and the use of an artificial neural network, we can show that this method is equal to the use of conventional volume determination. From a comparison with a spirometer connected in parallel as a reference, a mean error for tidal volume of −0.10 l and vital capacity of 0.09 l is obtained.