Geometry and Trigonometry

Until the specialized domain of Kinect development matures, developers will have to write code to detect poses, gestures, or control interface interactions. Frequently, this code will involve geometry and trigonometry. Included are several formulas and common uses of both in Kinect development. This type of math is used to triangulate the position of players, calculate the angles of joints, and determine distances from objects. Kinect is a 3D input device mapping a 3D world, and even if your application does not involve 3D graphics, many of the same fundamentals apply.

Remember, when triangulating joints and their relation to other objects within coordinate space, you only need two points to create a triangle. The third point can be arbitrary or derived from the other two points. Often we trying to calculate some property related to the two vectors, where the value of the third vector has no material effect on the calculated result.