Gravity Navigation

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GravNav: Using a Gravity Model for Multi-Scale Navigation Waqas Javed, Sohaib Ghani, Niklas Elmqvist Purdue University West Lafayette, IN USA Presented By: Waqas Javed 1 AVI 2012 May 21-24, 2012 ▪ Capri Island, Italy

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Presentation from ACM AVI 2012 in Capri, Italy on gravity navigation. Gravity navigation (GravNav) is a family of multi-scale navigation techniques that use a gravity-inspired model for assisting navigation in large visual 2D spaces based on the interest and salience of visual objects in the space. GravNav is an instance of topology-aware navigation, which makes use of the structure of the visual space to aid navigation. We have performed a controlled study comparing GravNav to standard zoom and pan navigation, with and without variable-rate zoom control. Our results show a significant improvement for GravNav over standard navigation, particularly when coupled with variable-rate zoom. We also report findings on user behavior in multi-scale navigation.

Transcript of Gravity Navigation

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GravNav: Using a Gravity Model for Multi-Scale Navigation

Waqas Javed, Sohaib Ghani, Niklas ElmqvistPurdue UniversityWest Lafayette, IN

USA

Presented By: Waqas Javed

AVI 2012May 21-24, 2012 ▪ Capri Island, Italy

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Lafayette

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Lafayette

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D. Fisher. Hotmap: Looking at geographic attention. IEEE Transactions on Visualization and Computer Graphics, 13(6):1184–1191, 2007.

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Gravity Navigation

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Related Work

• General and Multi-scale Navigation– Pan and zoom (Furnas and Bederson 2005)– Speed-dependent automatic zooming (Igarashi and Hinckley 2000)– OrthoZoom (Appert and Fekete 2006)

• Assisted Navigation– Topology aware navigation (Moscovich et al. 2009, Ghani et al. 2011)– Content aware scrolling (Ishak and Feiner 2006)

• Pointing– Semantic pointing (Blanch et al. 2004)– Sticky targets (Mandryk and Gutwin 2008)– Force-enhanced targets (Ahlström et al. 2006)

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Degree of Interest in Gravity Navigation

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Degree of Interest

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Gravity Model• Attention gravity vector

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Motor Space Model

• Using the attention gravity vector to manipulate the control display (CD) mapping– CD gain– CD direction

• Gravity panning• Gravity zooming

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User Study

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Task

• Zoomed-out overview to a zoomed-in detail view of a particular target

• The target was surrounded by distractor objects• 2xN distractor objects at a random position on the

periphery of every Nth imaginary circle• The target was a square the size of 10% of the viewport

size at 1:1 zoom factor• The square was red whenever viewed at less than full

scale factor, and blue otherwise• A collection of successively larger concentric rings

centered around the target

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Task Video

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Study Factors

• Navigation Technique (T)• Zoom Control Technique (Z)• Index of Difficulty (ID)

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Study Factors

• Navigation Technique (T)– Standard navigation (SN)– Gravity navigation (GN)

• Zoom Control Technique (Z)• Index of Difficulty (ID)

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Study Factors

• Navigation Technique (T)• Zoom Control Technique (Z)– Standard zoom control (SZ)– OrthoZoom (OZ)

• Index of Difficulty (ID)

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Study Factors

• Navigation Technique (T)• Zoom Control Technique (Z)• Index of Difficulty (ID)

– 5 different ID values (10, 15, 20, 25, and 30)

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Experimental Design

• Participants: 12 • Navigation Technique T: 2– SN (Standard Navigation)– GN (Gravity Navigation)

• Zoom Control Technique Z: 2– SZ (Standard Zoom Control)– OZ (OrthoZoom)

• Index of Difficulty ID: 5– 10, 15, 20, 25, 30

• Repetitions: 5

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Experimental Design

• Trials were organized in blocks based on zoom control technique Z

• Within each block T and ID factors were randomized

• Measures during each trial– completion time – cinematic interaction data

• Minimum five training tasks

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Experimental Hypothesis

• H1: GN will be faster than SN• H2: OZ will be faster than SZ• H3: GN will benefit more from OZ than SN

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Experimental Results

• Completion Time• Navigation Behavior• Subjective Feedback

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Completion Time

Factor Significant Effect

Navigation Technique

Zoom Control Technique

Index of Difficulty

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Completion Time

• GN was an average of 25.6% faster than SN

GN + OZ

1Fastest GN + SZ

2 SN + OZ

3 SN + SZ

4Slowest

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Navigation Behavior

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Subjective Feedback

• Participants were generally favorable in regards to OrthoZoom

• Few participants felt that they often overshot the target with OrthoZoom– “the [OrthoZoom] task sometimes got out of control.”

• A couple of participants stated that some trials were easier than others – “sometimes it felt as if my cursor snapped onto the target,

whereas other times not so much.”– Another thought that targets seemed to “pull in the cursor.”

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Summary of Results

• Gravity navigation exhibited significantly faster completion times than standard navigation (confirming H1)

• Variable-rate zoom control using OrthoZoom resulted in significantly faster completion times than standard constant rate zoom control (confirming H2)

• Gravity navigation with OrthoZoom was significantly faster than gravity navigation with constant-rate zoom control whereas no significant such difference was found for standard navigation (confirming H3)

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Conclusion

• A novel family of multi-scale navigation techniques that we call GravNav

• GravNav utilizes the topology of the underlying visual space to assist navigation

• Quantitative evaluation of the GravNav technique

• Study results confirm the usefulness of the new technique

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Thank You!

Contact Information:Waqas JavedSchool of Electrical & Computer EngineeringPurdue UniversityWest Lafayette, IN, USA

E-mail: [email protected]

http://engineering.purdue.edu/pivot/

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