Scalable real-time motion recognition

A system for recognizing human motion from skeletal data derived from image data comprising:

• a camera for repeatedly capturing image data sets of a human body;
• one or more processors communicatively coupled to the camera for receiving the image data sets and having access to a memory for storing the body data sets;
• the one or more processors executing software for representing the human body in the image data sets as a human skeleton model of joints;
• the one or more processors executing software for generating a body-based coordinate 3-D reference system having a frame of reference defined with respect to a position of a plurality of joints grouped together as a single rigid body;
• the one or more processors executing software for determining positions of first degree joints, adjacent the single rigid body, in relation to a position of the single rigid body;
• the one or more processors executing software for determining positions of second degree joints, adjacent the first degree joints, in relation to positions of the first degree joints;
• and
• the one or more processors executing software for determining a motion of at least one body part using the body-based 3-D coordinate reference system and the determined positions of the first and second degree joints.

One or more computer readable storage media having encoded thereon instructions for causing at least one processor to perform a method for recognizing a gesture from image data, the method comprising:

• (a) receiving sets of skeletal data representing a human body in a fixed camera-based three-dimensional (3-D) coordinate reference system having a frame of reference defined with respect to a point in a camera's field of view;
• (b) conforming the sets of skeletal data received in said step (a) to a body-based coordinate 3-D reference system having a frame of reference defined with respect to a position within a rigid body portion of a skeletal model, the body-based coordinate 3-D reference system being independent of the camera's field of view;
• (c) representing the body-based coordinate 3-D reference system by one of:
• i) a plurality of angles that rotate the skeletal data back into the fixed camera-based 3-D coordinate reference system and ii) an orientation matrix;
• (d) determining a motion of at least one body part using the plurality of angles that rotate the skeletal data back into the fixed camera-based 3-D coordinate reference system;
• and
• (e) determining whether a gesture has been made by at least one body part based on the determined motion of the at least one body part.