Tracing and Sketching Performance using Blunt-tipped Styli on

Direct-Touch Tablets

Sriram Karthik Badam, Senthil ChandrasegaranNiklas Elmqvist, Karthik Ramani

2

Tablet computers: transitioning from paper

Digital medium: content creation

3

4

Digital design mediumDedicated

Mobile

5

Finger Input

6

Digital design input styli

*

7

The Designer’s Notebook

8

Typical product design

Sketch primitives

Develop a model from primitives

Improve quality by tracing over

Can digital design tools replace paper for this?

9

Aspects of direct-touch sketching

friction

occlusion

parallax

familiarity

10

Related WorkAccot and Zhai

(1999)

Zabramski et al. (2011)

11

Study14 participants

(13 male, 1 female)

3 medium + input

multiple shapes

2 tasks Tracing Sketching

12

Tracing

x 3 repetitions

• Time taken for each trace

• Failures to keep to the tunnel

• Questionnaire

x 3 media

13

What’s better?

Tracing speed

Fast to Slow

*

7.27 sec 7.69 sec 8.58 sec

* significant with p-value <= .05

14

What’s better?

Tracing failures

Least to Most

320

84

15

Tracing task - survey

Comfortable

Confident

Accurate

14

14

14

12

10

10

5

2

1

16

Sketching

x 3 repetitions

x 3 medium

• Sketch Quality – Crowdsourced voting!

• Questionnaire

A B C D

17

What’s better?

Sketch quality

High to Low

*

* significant with p-value <= 0.05

18

Comfortable

Confident

Accurate

14

14

14

9

8

7

9

8

3

Sketching task - survey

19

AspectsFamiliarity (self reported) occlusion

friction parallax

different* pen-paper different than tablet

pen-paper different than tablet

< <

>

< =

20

Findings

Tracing speed

Tracing failures (fewer)

Sketch quality of cubes

Sketch quality of cylinders

* *** *

(*) significantly better performance than the unmarked media

-----------------------------same---------------------------

21

Blunt tipped vs. Sharp tipped styli

22

Follow-up6 participants

(5 male, 1 female)

2 medium + input

multiple shapes

2 tasks Tracing Sketching

23

Data collection

• Time taken for each trace

• Failures to keep to the tunnel

• Sketch Quality – expert voting (4 independent judges)!

Tracing (5 shapes) Sketching (3 shapes)

• Questionnaire • Questionnaire

24

What’s better?

Tracing speed

Fast to Slow

7.59 sec 7.71 sec

25

What’s better?

Tracing failures

Least to Most

1115

26

Tracing task - survey

Comfortable

Confident

Accurate

5

3

2

4

5

5

27

What’s better?

Sketch quality

High to Low

• Sketches drawn with hard-tipped stylus were chosen three times more frequently

28

Sketching task - survey

Comfortable

Confident

Accurate

5

4

2

3

3

4

29

Aspectsfamiliarity occlusion

friction parallax

= >

different*

=

30

Findings

Tracing speed

Tracing failures (fewer)

Sketches*

(*) sketches selected three times more frequently

31

The Designer’s Notebook

32

Implications

Case for blunt-tip stylus

33

IIS-1227639

IIS-1249229

IIS-1253863

Donald W. Feddersen Chaired Professorship

Purdue School of Mechanical Engineering.

Acknowledgment

Questions?

S. Karthik Badam

sbadam@purdue.edu