We introduce a new snapping technique, Oh Snap, designed specifically for users of direct touch interfaces. Oh Snap allows users to easily align digital objects with lines or other objects using 1-D or 2-D translation or rotation. Our technique addresses two major drawbacks of existing snapping techniques: they either cause objects to "jump" to snap locations, preventing placement very close to those locations, or they "expand" motor space so that on direct-touch interfaces objects lag behind the user’s finger. Oh Snap addresses both of these problems using an asymmetric velocity profile similar to a technique for filtering degrees of freedom in multi-touch gestures that was introduced by Nacenta et al. (2009). Oh Snap applies the velocity profile to multiple "snapping" constraints. A user study revealed a 40% performance improvement over no snapping for 1-D translation, 2-D translation, and rotation tasks when snap lines or angles were targeted. We found that Oh Snap performs no worse than traditional snapping, while retaining its important functional benefits. The study also investigated optimal parameter settings and Oh Snap’s accuracy in supporting the placement of objects near to, but not at, snap locations, which traditional snapping techniques do not support. Oh Snap was found to be competitive with non-snapping interfaces for these tasks.


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  author  = {Jennifer Fernquist and Garth Shoemaker and Kellogg S. Booth},
  title   = {"Oh Snap" - Helping Users Align Digital Objects on Touch Interfaces},
  journal = {Proceedings of INTERACT 2011},
  year    = {2011},
  pages   = {to appear}