Prof. Dr. Patrick Baudisch

Touch on Curved Surfaces

For a long time, industrial designers have created (non-functional) prototypes of non-planar touch devices, such as bracelets and rings. With recent advances in display and touch technology, such as OLED, E-ink, and capacitive sensing, these prototypes will soon become reality. To help interaction designers to create the best possible interfaces on such devices, our CHI 2011 paper "touch on curved surfaces" presents two user studies that determine how device curvature impacts touch input. We report three main results:

Research agenda

Our CHI 2011 paper is only a first step towards the bigger goal. This ultimate goal is to create a metric for evaluating the shape of (mobile) devices.  Similar to how wind tunnels and the notion of air resistance have informed the shape of cars for decades, we think that a metric for device shape will bring rigor to the discussing of the shape of devices.

Curve touch device

In order to study touch on curved surfaces, we have created the FTIR "curve touch" device shown on the right. It consists of (1) an acrylic touch surface, (2) a set of 8 bright white LEDs on each of four sides that inject light into the acrylic and (3) a high-definition web camera that observes the touch surface from below. We obtained exact surface curvatures by stamping appropriately-sized spheres into the heated 3mm acrylic. This device allowed us to observe the exact contact area between finger and device, which was essential to determining touch location and thus the exact inaccuracy of touch input on the respective curvatures and target locations.


Roudaut, A., Pohl, H., and Baudisch, P. Touch on Curved Surfaces. In Proceedings of CHI 2011, 1011-1020.
 PDF (3.1M)