Design and Evaluation of 3D Selection Techniques based on Progressive Refinement

with Doug A. Bowman

My thesis project is about the design and implementation of 3D selection techniques that use progressive refinement of the set of selectable objects to reduce the required precision of the task. Progressive refinement is an approach that allows users to perform a precise selection using multiple rough selections that require very little precision.We have designed several different techniques that use this design:

SQUAD (Sphere-casting refined by QUAD menu)
This selection technique uses two distinct refinement phases. In the first phase, the user specifies a volume containing the target object. The user then refines the initial selection progressively by selecting the subset of objects containing the target from a four-item menu displaying all the remaining objects, until the target is finally selected. SQUAD makes it possible to accomplish precise selection without requiring the user to use precise actions at any moment during the selection task.



Discrete Zoom
The discrete zoom technique uses 2D menus for specification of the zooming area, discrete actions to define when to zoom, and ray-casting. The user can choose to point directly to the object and select it, or to point to the region of the screen that contains it and perform zoom to increase the target size. Once the object is selected, the user goes back to the initial view, and is able to perform other actions.



Continuous Zoom
The continuous zoom technique works in a similar way to discrete zoom, but instead of using quadrants for zooming, it zooms in the direction of the cursor continuously. This way, users can simply point roughly toward the object and zoom in until the target is large enough for selection.



We are currently in the process of designing improved versions of these techniques and new ones based on different concepts.