Move to Improve: Promoting
Physical Navigation to
Increase User Performance
with Large Displays
Robert Ball
Virginia Tech
November 10, 2006
Motivation: Cuban Missile Crisis:
September/October 1962
U-2 Spy plane takes high-resolution
pictures of parts of Cuba
http://www.gwu.edu/~nsarchiv/nsa/cuba_mis_cri/1.jpg
Picture taken of SA-2
missile construction site
http://www.gwu.edu/~nsarchiv/nsa/cuba_mis_cri/1.jpg
Analysis of pictures



U-2 Spy place takes high-resolution pictures.
Analyst must
interpret pictures
with this:
Why: physical
navigation
Inside the CIA’s National Photographic
Interpretation Center (NPIC), Washington D.C., 1962.
http://www.gwu.edu/~nsarchiv/nsa/cuba_mis_cri/7.jpg
Related Work
Games!
Related work – other domains and
applications
Physical navigation related work
HMD
Headmounted
display
CAVE
Experiment Motivation
Research Questions:
 Do users prefer physical navigation with
large, high-resolution displays? Why?
 If so, does this result in improved user
performance?
 Is physical navigation truly more beneficial
than virtual navigation in terms of
performance time?
Experimental Design – data and
visualization



3,500 houses for sale in Houston, TX
Semantic zooming scheme, zooming only resulted in
more information being displayed.
To see all of the houses with all the details shown would
require about a 100-monitor display.
Experimental Design – display,
interaction, and tracking

24 tiled monitors
Wireless mouse
 Vicon system

Experimental Design – tasks

4 tasks:

Navigation
 Search
 Pattern finding
 Insight finding

Between-subject design
Insight task:



Within-subject design
Used paper, pen, and stand.
No correct answers.
Other tasks:


Walked and spoke answer.
Only one correct answer.
Experiment results - performance

2-way ANOVA: main effects for
 display
width (F(1,1324)=20.56, p<0.01)
 task type (F(2,1324)=77.05, p<0.01)

Tukey HSD analysis showed different task
types were all in different groups, so:
Task
Main effect of
display width
navigation
(F(1,508) = 118.9, p<0.01)
search
(F(1, 762) = 38.18, p<0.01)
pattern finding
(F(1, 90) = 3.53, p=0.06)
Experiment results – performance,
cont.
Main effect of
display width
Task
navigation
(F(1,508) = 118.9, p<0.01)
search
(F(1, 762) = 38.18, p<0.01)
pattern finding
(F(1, 90) = 3.53, p=0.06)
Performance time (s)
Performance Times
30
25
20
15
10
5
0
1
2
3
4
5
6
7
8
Display width (in number of columns)
Navigation
Search
Experiment results - Performance
We found no significant results based on
the level of insight for the fourth task.
 So, we focus on results for the first three
tasks in this section.

Virtual Navigation Analysis – zooms

2-way ANOVA: main effects for
 task
type (F(3,1400)=416.2, p<0.01)
 display width (F(1,1400)=34.8, p<0.01)
 near-significant interaction of task type and
display width (F(3,1400)=2.4, p=0.06).
Virtual Navigation Analysis – zooms
per task
navigation - zooms
(F(1,508)= 144.6, p<0.01)
navigation - panning
not significant
search - zooms
(F(1,762) =114.1, p<0.01)
search - panning
(F(1,762) = 26.7, p<0.01)
pattern - zooms
not significant
pattern - panning
(F(1,90) = 7.8, p<0.01)
Number of zooms
Number of zooms
Tasks - Metrics
Main effect of
display width
25
20
15
10
5
0
1
2
3
4
5
6
7
8
Display width (in number of columns)
Navigation
Search
Pattern
Virtual Navigation Analysis – pans

2-way ANOVA: main effects for
 task
type (F(3,1400)=301.3, p<0.01)
 display width (F(1,1400)=63.86, p<0.01)
 interaction of task type and display width
(F(3,1400)=17.22, p<0.01).
Virtual Navigation Analysis – pans
per task
navigation - zooms
(F(1,508)= 144.6, p<0.01)
navigation - panning
not significant
search - zooms
(F(1,762) =114.1, p<0.01)
search - panning
(F(1,762) = 26.7, p<0.01)
pattern - zooms
not significant
pattern - panning
(F(1,90) = 7.8, p<0.01)
200
150
100
50
0
1
2
3
4
5
6
7
8
Display width (in number of columns)
Navigation
Search
Number of pans - pattern task
Number of pans
Tasks - Metrics
Main effect of
display width
Number of pans
Number of pans - navigation and
search tasks
1200
1000
800
600
400
200
0
1
2
3
4
5
6
7
8
Display width (in number of columns)
Physical Navigation Analysis
Douglas-Peucker algorithm used to
guarantee that what we were analyzing
was actual movement - not jitter.
Physical Navigation Analysis, cont.

2-way ANOVA for total X distance: main
effects for
 task
type (F(3,1400)=75.1, p<0.01)
 display width (F(1,1400)=24.1, p<0.01)
 interaction of task type and display width
(F(3,1400)=4.0, p<0.01)
Physical Navigation Analysis – per
task
Main effect of display width
navigation
not significant
search
(F(1,762) = 4.52, p=0.03)
pattern
finding
120
100
80
60
40
20
0
1
2
3
4
5
6
7
8
Display width(in number of columns)
Total Distance in the X Direction pattern task
(F(1,84) = 16.62, p<0.01)
Movement in inches .
Task
Movement in inches .
Total Distance in the X Direction search task
500
400
300
200
100
0
1
2
3
4
5
6
7
8
Display width(in number of columns)
Visualization of physical movement
Experiment conclusions
Do users prefer physical navigation with
large, high-resolution displays?
YES
When faced with a choice of physical or
virtual navigation, 100% of the participants
chose only to physically navigate.
Experiment conclusions
If so, does this result in improved user
performance?
YES
Performance time (s)
Performance Times
30
25
20
15
10
5
0
1
2
3
4
5
6
7
8
Display width (in number of columns)
Navigation
Search
Experiment conclusions
Is physical navigation truly more beneficial than virtual
navigation in terms of performance time?
YES

Virtual navigation has a greater negative correlation on
performance than physical navigation.



The number of zooms correlated with performance with a
correlation coefficient of 0.69.
The number of pans correlated with performance with a
correlation coefficient of 0.68.
However, physical distance traveled did not significantly
correlate with performance.
Future work
Do the results from this study extrapolate
to 3D data? To non-geospatial data?
 How does fatigue/longitudinal use of such
displays affect the results of this
experiment?
