Mapping between musical interfaces, and sound engines, is integral to the nature of an interface [3]. Traditionally, musical applications for touch surfaces have directly mapped touch coordinates to control parameters. However, recent work [9] is looking at new methods of control that use relational multi-point analysis. Instead of directly using touch coordinates, which are related to a global screen space, an initial touch is used as an 'anchor' to create a local coordinate space in which

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... equent touches can be located and compared. This local coordinate space frees touches from being locked to one single relationship, and allows for more complex interaction between touch events. So far, this method has only been implemented on Apple computer's small capacitive touch pads. Additionally, there has yet to be a user study that directly compares [9] against mappings of touch events within global coordinate spaces. With this in mind, we have developed and evaluated two interfaces with the aim of determining and quantifying some of these differences within the context of our custom large multi-touch surfaces [1].