TerraGuide: A Multi-Surface Environment for Visibility Analysis
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Terrain visibility analysis is a challenging task that is currently supported by complex tools with cumbersome user interfaces. In this thesis, we present TerraGuide, a novel multi-surface environment for exploratory terrain and visibility analysis. TerraGuide is based around a large interactive tabletop that displays a digital map from the top-down perspective. TerraGuide provides three tightly coupled visibility analysis techniques: a viewshed shows visibility in a cone drawn from the user’s touch point on the table, a panoramic view provides a 3D first-person view on a separate display, and a helicopter view allows the user to see terrain in 3D on a handheld tablet positioned over the table. We designed TerraGuide using three principles: TerraGuide computes views in real-time, TerraGuide couples views on different surfaces tightly, and users can easily switch between different views. These design principles affect the participants’ strategies and preference among techniques when using the TerraGuide system for terrain analysis tasks. A two-part user study compared these techniques and identified users’ strategies in solving a complex terrain analysis problem. The first part of the study compared the three techniques and measured performance, preference, confidence, and cognitive load during a simple analysis task. We found that the helicopter view improved participants’ completion time and accuracy when identifying the highest and lowest points on the terrain. In addition, the use of the 3D panoramic view worsened task completion time, yet increased participants’ confidence in their analysis. The second part of the study determined participants’ strategies when performing a more complex task. We identified three strategies used by participants and found they overwhelmingly adopted a bi-manual use of the tabletop viewshed and tablet-based helicopter techniques. This thesis gives insight into how multi-surface environments can be designed to allow for complementary use of techniques and fluid switching between them.