CubeExplorer: An Evaluation of Interaction Techniques in Architectural Education Hyunyoung Song¹, François Guimbretière¹, Michael A.Ambrose², Carl Lostritto² ¹Human-Computer Interaction Lab, Department of Computer Science, ²Architecture Program, School of Architecture, Planning and Preservation University of Maryland, College Park, MD 20742, U.S.A {hsong, francois}@cs.umd.edu {ambrosem, carllos}@umd.edu Abstract. During the early stages of architectural training, tangibility plays an important role in developing spatial awareness. In such contexts, tangible user interfaces are believed to provide a significant advantage as they combine the affordances of both the physical and the digital world. We introduce CubeExplorer, a hybrid 3D conceptual aid that combines physical interaction and digital modeling in an effort to complement conventional architectural space-training tools (such as physical materials and digital CAD programs). Using a digital pen as an input mechanism, CubeExplorer lets users perform subtractive 3D geometric operations on a simple paper based cube model while observing the resulting model on a display. The tangibility of the model simplifies navigation and command execution, while the digital interface makes it easy for users to explore multiple alternative designs. To evaluate the potential of such an approach, we conducted a user study in a normal classroom environment where students were provided with physical (wooden block), hybrid (CubeExplorer), and virtual (FormZ) interfaces to complete the same assignment. Our evaluation showed that CubeExplorer combined the advantages of both digital and tangible media. The advantages of CubeExplorer over digital media were substantiated in a follow-up study comparing CubeExplorer and SketchUp in a similar building task. Keywords: Education, 3D modeling, pen-based interface, tangible user interface 1. Introduction One of the challenges in introductory architectural education is to develop the conceptual understanding of form and space in abstract ways [18]. Points, lines, and planes are used in increasingly sophisticated ways to describe geometric volumes of solids and voids. To do so, modern curricula are mixing physical media such as wood blocks, and digital media such as CAD programs, to help students discover these basic concepts in introductory classes. Unfortunately, both approaches come with advantages and disadvantages. Wood blocks offer a simplified format palette that they are easy to use, which helps students to focus on concepts. Yet, their physical restrictions might limit the scope of the students’ composition. For example, gravity