i247: information visualization and presentation marti hearst

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i247: Information Visualization and PresentationMarti Hearst

April 16, 2008

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Today

• 3D visualization– 3D in scientific visualization– Applying 3D to abstract data

• The PARC Information Visualizer and follow-ons• 3D for data graphics

– Navigating in 3D space– The debate: does 3D help?

• Cognitive abilities and 3D• 3D vs 2D

– Case Study: Helping Helicopter Pilots (scientific viz)

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3D and Scientific Visualization

• Visualizing information that is inherently 3D is a special case of infoviz– “Easier” in the sense that the 3D inherently makes sense– Still, you need to choose what to show and what not to

show.• Images from https://graphics.llnl.gov/flow.html

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Chimera (from UCSF)

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3D for Abstract Information

• Pioneering Work by Card and Robertson– Had state-of-the-art graphics hardware; wanted to

see what happens when pushing the boundaries– Motivated by Card & Moran’s theories of cognitive

architecture

• Information Visualizer (PARC)• WebBook/Webforager (PARC, 1996)• Data Mountain (MS Research, 1998)• Task Gallery (MS Research, 2000)

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• Objective: – Decrease the costs for performing information-

intensive tasks, or, alternatively, increase the scope of information that can be utilized for the same cost.

• Method:– Large Workspaces

– Make the immediate workspace virtually larger

– Real-Time Interaction – Maximize the interaction rates

– Visual Abstractions– Speed assimilation and pattern detection

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Information Workspaces

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Information Visualizer

research.microsoft.com/~ggr/gi97.ppt 17

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Web Forager

http://research.microsoft.com/ui/TaskGallery/index.htm 24

9 23http://research.microsoft.com/ui/Taskgallery/pages/video.htm

Task Gallery (Robertson et al. 2000)

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Data Mountain

• Robertson, Czerwinski et al, 1998

• Follow-on to Information Visualizer

• Organizing bookmarks using pile metaphor

• Uses:– Spatial organization– 3D view with 2D interaction– Cartoon animation details– Subtle audio cues

• Debate: – Is this better than 2D?

http://research.microsoft.com/adapt/datamountain/video/datamtn.mpeg

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3D vs. 2D

• Cockburn & McKenzie ’02– Results for prior work with 3D systems are

primarily negative for viz of things that are not inherently in 3D, but really results are mixed

– Compared 2D, 2½D and 3D views of web page thumbnails

– Did this for both physical and virtual interfaces– Compared sparse, medium, and dense displays

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3D vs. 2D: Cockburn & McKenzie ’02

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3D vs. 2D

• Cockburn & McKenzie ’02– Results:

• Time taken sig. increased through 2D -> 3D interfaces

• Subjective assessment sig. decreased 2D -> 3D• Performance degraded with denser problems• 3D virtual interface produced the slowest times• People prefered the physical interfaces• People were better at using their spatial memory

than they expected to be• There was a problem with the physical 2½D

display

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The Role of Cognitive Abilities

• Leitheiser & Munro ‘95– Summarizes the results of earlier psychological

research on spatial aptitiude – Also summarizes work on effects of spatial aptitude

and UI use– Presents a study comparing a GUI with a command

line interface, taking spatial abilities into account

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The Role of Cognitive Abilities • Leitheiser & Munro ’95• Hypotheses:

– Users with high spatial ability would benefit more from the GUI than those with low spatial ability (H1)

– Users with high verbal ability would perform better on command line interfaces (H2)

• Tasks:– Obtain system time, list files, look up a file update time, open a

subdirectory, move a file, copy a file, etc– Between subjects GUI (Mac) vs. Command line (DOS)

• Findings:– H1 supported– H2 not supported– Everyone did better on the GUI

• Low spatial ability users using the GUI required 90% of the time needed for command line interface

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Gender differences and 3D

• Previous studies often found gender differences in 3D navigation

• Czerwinski et al. wondered why; saw a hint in one study, did a followup study in detail

• Idea: change the assumptions– Make screen wider– Gender performance differences disappear– Both improved

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3D and Data Graphics• There have been lots of attempts to 3D-ify these• Results seemed mixed• Some modern versions of the ideas are here:

– http://www.oculusinfo.com/demos.html– http://www.oculusinfo.com/softwareproducts.html

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Interacting with 3D spaces

• Path-drawing for 3D walkthrough, – Igarashi et al, UIST ’98

• Problem: interacting with 3D via 2D screens• Solution: be clever about how to convert 2D to

3D based on what the user is likely to intend

http://www-ui.is.s.u-tokyo.ac.jp/~takeo/video/navi.mpg

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Creating in 3D Spaces

• Teddy: A 3D Drawing System– Igarishi 1999

http://www-ui.is.s.u-tokyo.ac.jp/~takeo/video/teddy.avi

http://www-ui.is.s.u-tokyo.ac.jp/~takeo/teddy/teddy/teddy.html

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Other 3D Creation Tools

• Lots of other great ideas from Igarashi’s lab:– http://www-ui.is.s.u-tokyo.ac.jp/projects/index.html

21Slides from Heiser et al.

Sequences of Steps vs 3D + Animation

• Heiser, Phan, Agrawala, Tversky, Hanrahan ‘04• Domain: assembly instructions• Identify

– How people conceive of 3D assemblies– How people comprehend visual instructions

• Validate– Build automated instruction design system– Evaluate usability of resulting instructions


Ensure Visibility of Parts

• Show parts added in each step• Show mode and location of attachment• Avoid changing viewpoint• Use physically stable orientation


Structural diagrams

Action diagrams

Illustrate Assembly Operations

• Use action diagrams rather than structural• Use arrows and guidelines to indicate attachment

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Improving Aviation Safety with Visualization

• Cecilia Aragon, graduated from here• Goal: reduce helicopter landing accidents

caused by invisible air turbulence• Approach: use a new technology called lidar

and try to visualize its output• Finding: it helped reduce simulated accidents

(!) but only when the visualization was made as simple as possible.

25Slide by Cecilia Aragon

Motivation

• Invisible airflow hazards cause aircraft accidents – Wind shear– Microbursts– Vortices (turbulence)– Downdrafts– Hot exhaust plumes

• Crash of Delta Flight 191 at DFW 1985 (microburst)• NTSB database 1989-99

– 21,380 aircraft accidents– 2,098 turbulence/wind related


Preliminary Usability Study


Preliminary usability study: goals

• Assess efficacy of presenting airflow data in flight

• Obtain expert feedback on presentation of sample hazard indicators to refine design choices


Usability study: low-fidelity prototype

• Rhino3D (3D CAD modeling program)– Easy access to ship models, ease of rapid

prototyping– Chosen over 2D paper prototype, MS Flight

Simulator, WildTangent, VRML-based tools, Java and Flash

• Series of animations simulating helicopter’s final approach to landing

• Different types of hazard indicators• Get pilot feedback and suggestions

(interactive prototyping)


Low-fi usability study screen shots


Low-fi usability study participants

• Navy helicopter test pilot, 2000 hours of flight time, 17 years experience

• Navy helicopter flight test engineer, 2000+ hours of simulator time, 100 hours of flight time, 17 years experience

• Civilian helicopter flight instructor, 1740 hours of flight time, 3 years experience


Low-fi usability study results

• All participants said they would use system• Feedback on hazard indicators:

– Color: all preferred red/yellow only– Transparency: should be visible enough to get

attention, but must be able to see visual cues behind it

– Depth cueing: all preferred shadows below object, #1 said shadows alone sufficient. #2 wanted connecting line. No one wanted tick marks or numeric info.

– Texture: #1, #2 didn’t want. #3 suggested striping– Shape: Rectilinear and cloud shapes favored. Keep it

simple! Watch for conflicting HUD symbology.


Flight Simulation Usability Study


Flight Simulation Usability Study

• Implement visual hazard display system in simulator based on results from low-fidelity prototype

• Advanced Rotorcraft Technology, Inc. in Mountain View, CA, USA– High-fidelity helicopter flight simulator– Accurate aerodynamic models

• Use existing ship and helicopter models, flight test data

• Simulated hazardous conditions, create scenarios, validated by Navy pilots and flight engineers


Flight Simulation Usability Study: Participants

• 16 helicopter pilots– from all 5 branches of the military (Army, Navy, Air

Force, Coast Guard, Marines)

– civilian test pilots (NASA)

– wide range of experience• 200 to 7,300 helicopter flight hours (median 2,250 hours)

• 2 to 46 years of experience (median 13 years)

• age 25 to 65 (median age 36)

• No previous experience with airflow hazard visualization


Simulation Experiment Design• 4 x 4 x 2 within-subjects design (each pilot flew

the same approaches)• 4 shipboard approach scenarios

• 4 landing difficulty levels (US Navy Pilot Rating Scale - PRS 1-4)

• Each scenario was flown at all difficulty levels both with and without hazard indicators

• Orders of flight were varied to control for learning effects


Airflow Hazard Indicators in Simulator


Hypotheses

1. Crash rate will be reduced by the presence of hazard indicator (LD 3).

2. Crashes will be eliminated by red hazard indicator if a standard operating procedure (SOP) is given to the pilots (LD 4).

3. Hazard indicator will not cause distraction or degradation in performance in situations where adequate performance is expected without indicator (LD 2).

4. Pilots will say they would use airflow hazard visualization system


Hypothesis 1 confirmedPresence of the hazard indicator reduces the frequency of crashes during simulated shipboard helicopter landings (t-test for paired samples, t=2.39, df=63, p=0.00985). 19% --> 6.3%

Landing Difficulty 3:Crash Rate vs. Presence of Hazard

Indicator

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Absent Present

Hazard Indicator

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Hypothesis 2 confirmedPresence of the red hazard indicator combined with appropriate instructions to the pilot prevents crashes (t=4.39, df=63, p < 0.000022). 23%-->0%

Landing Difficulty 4:Crash Rate vs. Presence of Hazard Indicator

0.00

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Absent Present

Hazard Indicator

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Hypothesis 3No negative effect of hazard indicator. 8%-->8%

Landing Difficulty 2:Crash Rate vs. Presence of Hazard Indicator

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0.02

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Absent Present

Hazard Indicator

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Hypothesis 3 (cont’d)Pilots believe hazard indicators were not distracting (Probe 6 results).

6. The airflow hazard visualization distracted me from the task of flying the aircraft.

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StronglyDisagree

Disagree Neither AgreeNor Disagree

Agree StronglyAgree

Pilot response

6% Agree, 94% DisagreeMedian 2, Std Dev 0.7

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Hypothesis 4 confirmedPilots would use the system (Probe 21 results).

21. I would use this display system if it were available on my aircraft.

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StronglyDisagree


Agree StronglyAgree

Pilot response

81% Agree, 13% DisagreeMedian 4.5, Std Dev 1.0

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Analysis by Pilot Experience Level• Same general trends -- but small sample size• No significant difference between the groups

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0.05

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Crash Rate

Low Mod Hi

Pilot Experience Level

Crash Rate vs. Experience Level

LD 2/No

LD 2/Haz

LD 3/No

LD 3/Haz

LD 4/No

LD 4/Haz


Analysis of Subjective Data94% found hazard indicators helpful

18. The presence of the hazard indicators gave me more confidence as to the state of the winds and

airwake on deck.

0123456789

StronglyDisagree


Agree Strongly Agree

Pilot response


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Analysis of Subjective DataIs motion (animation) helpful or distracting?

14. It would be distracting if the hazard indicator showed airflow motion.

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StronglyDisagree


Agree Strongly Agree

Pilot response


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Conclusions• Flight-deck visualization of airflow hazards yields

a significant improvement in pilot ability to land safely under turbulent conditions in simulator

• Type of visualization to improve operational safety much simpler than that required for analysis

• Success of user-centered design procedure

i247: information visualization and presentation marti hearst

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