I!!la HumanFactors inComputing Systems Passive Real-World Interface Props for

We claim that physical manipulation of familiar real-world objects in the user’s real environment is an important technique for the design of three-dimensional user interfaces. These real-world passive inte~ace props are manipulated by the user to specify spatial relationships between interface objects. By unobtrusively embedding free-space position and orientation trackers within the props, we enable the computer to passively observe a natural user dialog in the real world, rather than forcing the user to engage in a contrived dialog in the computer-generated world. We present neurosurgical planning as a driving application and demonstrate the utility of a head viewing prop, a cutting-plane selection prop, and a trajectory selection prop in this domain. Using passive props in this interface exploits the surgeon’s existing skills, provides direct action-task correspondence, eliminates explicit modes for separate tools, facilitates natural two-handed interaction, and provides tactile and kinesthetic feedback for the user. Our informal evaluation sessions have shown that with a cursory introduction, neurosurgeons who have never seenthe interface can understand and use it without training. KEYWORDS three-dimensional interaction, gesture input, two-hande

Passive Real-World Interface Props for Neurosurgical Visualization

We claim that physical manipulation of familiar real-world objects in the user's real environment is an important technique for the design of three-dimensional user interfaces. These real-world passive interface props are manipulated by the user to specify spatial relationships between interface objects. By unobtrusively embedding free-space position and orientation trackers within the props, we enable the computer to passively observe a natural user dialog in the real world, rather than forcing the user to engage in a contrived dialog in the computer-generated world. We present neurosurgical planning as a driving application and demonstrate the utility of a head viewing prop, a cutting -plane selection prop, and a trajectory selection prop in this domain. Using passive props in this interface exploits the surgeon's existing skills, provides direct action-task correspondence, eliminates explicit modes for separate tools, facilitates natural two-handed interaction, and provides tactile ..

A Three-Dimensional User Interface for Neurosurgical Visualization

We describe a three-dimensional user interface for pre-operative neurosurgical planning based on the physical manipulation of familiar real-world objects in free space. Using these passive interface props, neurosurgeons can apply their existing skills to specify spatial relationships in a natural and direct manner. The interface currently employs a head viewing prop, a cuttingplane selection prop, and a trajectory selection prop. Each prop is a simple real-world tool, the position and orientation of which is tracked by the computer. The behaviors associated with each prop serve as "interaction primitives" which can be composited to describe complex spatial relationships, resulting in a powerful, expressive, and conceptually simple user interface. From the surgeon's perspective, the interface is analogous to holding a miniature skull which can be "sliced" and "pointed to" using the cutting-plane and trajectory props. Our informal evaluation sessions have shown that with a cursory i..

The Props-Based Interface for Neurosurgical Visualization

this paper focuses on the pre-surgical planning phase, which usually takes place on the morning of surgery. To develop a plan, the surgeon uses visualization, measurement, and other planning tools to select the surgical targets and to select a path to those targets that produces the least possible damage to viable tissue. To plan the best possible trajectory, the surgeon needs to understand the spatial relationships between the targets, surrounding structures, functional areas which must not be damaged, and feasible entry points. Visualizations of the cortical surface, proposed surgical trajectories, and volume cross-sections at both orthogonal and oblique angles can all help the neurosurgeon to make informed decisions. Software usability is crucial to get neurosurgeons to actually use advanced visualization software in the clinical routine. We have designed interaction techniques which facilitate use of the software by surgeons, without need for technical assistance. Rather than typing in commands or moving sliders with a mouse, the neurosurgeon thinks in terms of real objects in real space; a three-dimensional user interface should allow the neurosurgeon to work and think in these same terms. As one surgeon put it, "I want a skull I can hold in my hand." The user interface for a neurosurgical planning and visualization system must permit the surgeon to work quickly. The surgeon must cope with frequent distractions, and therefore must be able to quickly detach from the user interface, both physically and cognitively. Thus, the interface must not encumber the surgeon with devices such as gloves or head-mounted displays that will be difficult to remove, and it must not have explicit modes that are easily forgotten during a phone call or a discussion with a colleague. O..