  Research in user interaction with mixed reality environments using multiple
displays has become increasingly relevant with the prevalence of mobile devices
in everyday life and increased commoditization of large display area
technologies using projectors or large displays. Previous work often combines
touch-based input with other approaches, such as gesture-based input, to expand
the possible interaction space or deal with limitations of other
two-dimensional input methods. In contrast to previous methods, we examine the
possibilities when the control-display (C-D) ratio is significantly smaller
than one and small input movements result in large output movements. To this
end one specific multi-display configuration is implemented in the form of a
spatial-augmented reality sandbox environment, and used to explore various
interaction techniques based on a variety of mobile device touch-based input
and optical marker tracking-based finger input. A small pilot study determines
the most promising input candidate, which is compared to traditional
touch-input based techniques in a user study that tests it for practical
relevance. Results and conclusions of the study are presented.
