In recent years 3D has gained increasing amount of attention - interactive visualization of 3D data has become increasingly important and widespread due to the requirements of several application areas, and entertainment industry has brought 3D experience to the reach of wide audiences through games, 3D movies and stereoscopic displays. However, current user interfaces (UIs) often lack adequate support for 3D interactions: 2D metaphors still dominate in GUI design, 2D desktop systems are often limited in cases where natural interaction with 3D content is required, and sophisticated 3D user interfaces consisting of stereoscopic projections and tracked input devices are rarely adopted by ordinary users. In the future, novel interaction design solutions are needed to better support the natural interaction and utilize the special features of 3D technologies. In this workshop we address the research and industrial challenges involved in exploring the space where the flat digital world of surface computing meets the physical, spatially complex, 3D space in which we live. The workshop will provide a common forum for researchers to share their visions of the future and recent results in the area of improving 3D interaction and UI design.