Shaping 3-D Volumes in Immersive Virtual Environments

Rasmus Stenholt

Publikation: Ph.d.-afhandling

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Abstract

Shaping 3-D volumes is an important part of many interactions in immersive virtual environments. The range of possible applications is wide. For instance, the ability to select objects in virtual environments is very often based on defin- ing and controlling a selection volume. This is especially true, if the intention is to select multiple objects. Another important application area is the manipula- tion of objects through the use of controllable handles, or widgets. Such widgets are often associated with a bounding volume around the object to be manipu- lated. Such techniques are both well-known in 2-D and 3-D contexts. A third application area is the task of 3-D modelling. In this case, the shaping of simple 3-D volumes is an intrinsic part of building a complex 3-D model from primitive shapes such as boxes, spheres, and cylinders.
This thesis presents three separate, but sequential, papers within the area of volume shaping. As such, each paper builds on the results of its predecessors. The first paper deals specifically with the task of shaping a 3-D box. Boxes are arguably one of the most commonly used 3-D shapes, both in real life and in virtual worlds. Therefore, the problem of efficiently and precisely defining a 3-D box is a fundamental one to investigate. The first paper does this by analysing the practical task of defining a 3-D box as the equivalent task of defining its degrees- of-freedom. This analysis leads to the introduction of a new way of shaping a box from just three of its corners organized in a specific configuration. Subsequently, box shaping techniques based on this idea are formally evaluated in a user study to be significantly more precise and no slower than existing techniques.
The second paper focuses on exploration and perception of structures in 3-D scatterplots. In data mining contexts, being able to perceive the shape of a struc- ture is a prerequisite for making precise subsequent interactions such as selec- tions and annotations. The paper introduces a new type of 3-D glyph rendering, which potentially diminishes the negative effects of clutter while reinforcing the perception of shapes. This new glyph type is evaluated against regular glyphs under various experimental circumstances, and is found to improve perception of structures and shapes in cluttered conditions. Furthermore, two volumet- ric density thresholds are discovered. Showing 3-D scatterplots with densities above/below these thresholds significantly changes the shape perception perfor- mance of users.
In the third and final paper, volume shaping is used in the context of efficient selection of multiple objects. The paper introduces a new technique, the magic wand, which automates a large part of the user’s work in such tasks. This tech- nique is compared to two other techniques, a spherical brush and a box-shaped
lasso, in an evaluation which seeks to identify the pros and cons of the tools. The magic wand proves to be faster to use than the other, but only in certain geomet- ric scenarios. The brush, on the other hand, performs decently across most of the tested scenarios. The box lasso was judged by the users to be difficult to use com- pared to the other techniques, even when the geometric scenario was perfectly fit for a box-shaped tool.
OriginalsprogEngelsk
Udgiver
ISBN'er, trykt978-87-992732-7-0
StatusUdgivet - nov. 2014

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    Rasmus Stenholt

    12/07/2012

    10 elementer af Mediedækning

    Presse/medie

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