Computerised musical instrument using motion capture and analysis

A musical instrument, in particular a percussion instrument such as a drum kit, operates based on motion capture and analysis. Markers 102, which may be held or worn by the musician 107, are observed by an image processor 104, 105 which determines the position of at least two markers in the images. The processor distinguishes between the different markers (e.g. left hand, right hand, right foot) by comparing the position and/or size of the markers in the current image, or by comparing markers in two or more images, and triggers audio outputs accordingly. For example, the processor may detect a drum hit when a marker undergoes a sharp reversal of its motion direction after having reached a sufficient speed. The processor may determine which virtual drum the musician intends to hit by comparing the position and size of the marker at the instant of the hit to the position and size attributes of each drum. The processor may select the nature of each audio signal and it volume, according to which drum was hit and as a function of the speed of the marker that triggered the drum hit in the instants before the hit.