For the fourth time in five years, a team of Virginia Tech doctoral students from the College of Engineering's Department of Computer Science and Center for Human-Computer Interaction has won the top prize in the IEEE 3-D User Interfaces contest.

The contest, sponsored by the Computer Society of the Institute for Electrical and Electronics Engineers, was held at the 2014 Symposium on 3-D User Interfaces in Minneapolis, Minn. This year's competition focused on three-dimensional point clouds, dense sets of points in 3-D space.

Point clouds are commonly produced by devices such as laser scanners. For example, a building can be scanned to obtain a detailed 3-D geometric model. The contest required teams to design and build systems for labeling such point clouds. This challenging task involves the precise selection of regions of points in 3-D space so that those points can be labeled.

The Virginia Tech team devised a solution entitled "Slice-n-Swipe" that provided multiple virtual tools to allow users to annotate point clouds using natural in-air gestures. For example, the "chef's knife" tool allowed the user to slice through the point cloud in mid-air, and then swipe away the unwanted points. Further slicing and swiping can refine the selection until only the desired points remain.

Additional tools included a resizable "bubble" that could be used to paint the desired points and a "lasso" similar to the tool used in painting and photo editing software. The system was implemented using the Leap Motion Controller, a new input technology that can track the positions of the user's hands and fingers in mid-air, and a 3-D mouse for controlling the user's view of the point cloud. 

The team members produced a YouTube video describing the entire system.

"Our design was inspired by the possibilities for natural gesture-based interaction with devices like the Leap Motion Controller," said Doug Bowman, faculty advisor to the team and professor of computer science. "The challenge was to design a precise and usable interface based on in-air motions that are inherently imprecise. We achieved this by designing a variety of tools and by using the concept of progressive refinement, where an initial rough selection is refined step-by-step until the precise result is accomplished."

Computer science team members were: Felipe Bacim of Porto Alegre, Brazil; Mahdi Nabiyouni of Tehran, Iran; and Cristian Moral Martos, a visiting Ph.D. student from the Polytechnic University of Madrid in Spain. Bacim has been a part of all four of Virginia Tech's winning teams in the 3-D UI contest in 2010, 2011, 2012, and 2014.

At the symposium, the team competed against four other finalists from around the world, including two teams from Brazil, one team from Germany, and one from France. Judging was done based on live demonstrations over two days, and the winner was determined by a popular vote of the symposium attendees, including top 3D user interface researchers from around the world.

In addition to the 3-D UI contest award, Nabiyouni, Bowman, and Bireswar Laha, a Ph.D. student in computer science from Konnagar, India, received an honorable mention best poster award for their poster, "Designing Effective Travel Techniques with Bare-Hand Interaction." This research also used the Leap Motion Controller and investigated how to enable navigation through 3-D environments based on in-air gestures.

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