Projection-screen-based multi-touch detection method and multi-touch system

The invention discloses a projection-screen-based multi-touch detection method, which relates to the technical field of human-computer interaction. The method comprises the following steps of: measuring a projection plane, calculating parameters of the projection plane, and performing background model training on the projection plane to form a background image; projecting a graphical interface to the projection plane, and judging whether to start monitoring touch operation or not; acquiring an image s of the touch operation; performing background segmentation on the image s acquired according to the background image, and extracting a foreground image; extracting fingertips from the foreground image, and filtering a palm, an arm and corresponding shades; judging contact points according to the spatial three-dimensional information of the extracted fingertips; and if the fingertips contact the projection plane, determining that the touch operation is effective, and returning to the position coordinates of the contact points. The invention also discloses a projection-screen-based multi-touch system. A human-computer interaction mode which is convenient, comfortable, accurate, real-time and stable is realized.