Torpeding – A New POI Placement Method

for Touch Screens

Ver 1.1 110630

Odd-Wiking Rahlff

Computas AS, Lysaker, Norway

oddwiking@gmail.com

Abstract: This paper compares a new method for touch-screen point-of-interest

placement, called Torpeding, which uses a fixed crosshair mark below which

the map itself is panned and zoomed. Experiments show that this way of

placing points of interest on a map is much better compared to the classic pin-

placement used on smartphones and tablets today.

Keywords: map interaction, pin, multi-touch, placement, interaction, usability,

POI, touch screen

Introduction

When indicating a point of interest (POI) on a touch screen map using a smartphone

or a tablet, the standard way of accomplishing this is by dragging and dropping the

shape of a pin until it hits the right spot.

Fig. 1. Classic pin placement of POI as used in the standard iPhone Map app

2 Torpeding – A New POI Placement Method for Touch Screens

This way of entering a POI by direct manipulation has several shortcomings:

The user has to literally „pinpoint‟ the small area of the pin in order to

initiate a move operation.

The user‟s fingertip is partly blocking the very area of most interest to the

user.

The user may not intuitively know where the „hot spot‟ of the pin or similar

icon is placed relatively to the fingertip.

If the user wants to inspect areas outside the visible part of the map or zoom

the map, the pin movement has to be postponed.

The operation requires using both hands in order to allow precise input.

The Torpeding method

A pin placement method which addresses and overcomes the deficiencies described

above, consists of the following: Instead of moving the pin, the map itself is moved

and adjusted underneath a transparent and fixed cross-hair icon which is „glued to the

screen‟, allowing for simultaneous pinch-zooming, panning and more unobstructed

view of the point of interest. We have studied this method, which is henceforth

referred to as Torpeding.

Fig. 2. Classic Pin vs. Torpeding POI-indication methods in our app

Torpeding – A New POI Placement Method for Touch Screens 3

Torpeding addresses the aforementioned shortcomings in the following ways:

The user initiates a move operation by invoking it through a normal sized

button.

The user‟s fingertip can be anywhere on the map leaving the whole screen

for a precise adjustment area. This means that the user does not have to

obscure the very area of most interest.

The user will always know exactly where the „hot spot‟ is placed: It is right

in the center of the crosshair.

Panning or zooming can be done at any time without changing the usage

mode.

The operation can be accomplished with one hand using the thumb for

precise navigation, making it easier to use in a mobile work setting.

Torpeding introduces, however, an issue of modality (the user must indicate that the

operation has finished) which will be addressed later.

Hypotheses

As we believed that Torpeding (T) was comparatively better than the classic “pin”-

placement (P) even taking the aforementioned modality into account, our hypotheses

thus became:

H1: T is faster than P

H2: T improves the accuracy of the final position compared to P

H3: T is no harder to understand than P

H4: T gives the user a higher degree of control

H5: The user likes T better than P

These are not independent: H5 will depend on all the others and encompass them.

The Experiment

In order to test the hypotheses we designed and implemented an iPhone test app.

The application was developed using the Human-Interface Guidelines from Apple [1],

it supports POI-task using the two methods and records time spent for each case. For

the map we used Google Maps [2].

We also wanted to get input on possible alternative uses of Torpeding.

4 Torpeding – A New POI Placement Method for Touch Screens

Experiment Setup and Method

For the test we needed a group of people who were used to smartphones and touch

screens, who were familiar with the pinch gesture, and likely to be interested in

testing new functionality. We therefore decided upon the following group:

Test group: 12 work colleagues, all in the IT sector but of different age and with

different degree of experience with smart phones. Eight of these were male, four

female. Their ages ranged from 26 to 51, with an average of 40 years of age and a

standard deviation of 8 years.

Each of the twelve users got the task of pinpointing a set of three different POIs (a

house corner, the middle of a roundabout, and a given car) with our app and using the

two different methods. Which one of the methods that was to be used first, was

chosen randomly by flipping a coin (5 used Torpeding first by this approach).

The application quantitatively measured the following for several trials for each user:

Time to accomplish fine tuning of placement, t, after having navigated to the

map containing the POI and pressing a button allowing for fine tuning of the

position.

After having used both methods, the user was asked to answer a small survey

containing the following questions for each of the two methods, using a Likert scale

ranging from 1 (very little) to 5 (very high):

How is the feeling of control?

How easy is it to understand?

How accurate do you think it is?

How many small adjustments does it need?

How fast is it?

How do you like this method?

Torpeding – A New POI Placement Method for Touch Screens 5

Results

The 12 users had varying experience with smart phones.

Fig. 3. Test users self-assessed smart phone experience

The users show overwhelmingly positive response for the new Torpeding method.

Fig. 4. Method comparison using a Likert scale ranging from 1 (very little) to 5 (very high)

0

1

2

3

4

#users

1,0

1,5

2,0

2,5

3,0

3,5

4,0

4,5

5,0

Feeling ofcontrol

Easy tounderstand

Experiencedaccuracy

Need forsmall

adjustments

Fast to use Like it

Pin

Torpeding

6 Torpeding – A New POI Placement Method for Touch Screens

POI placement time

The POI placement time was measured for each method and for each of the three test points.

Using the Torpeding method was consistently faster.

Fig. 5. Average POI placement times in seconds for the 12 users using the two methods

The measured average time to place the POI:

T-torpeding-average (TT-aver) = 2.9 sec ( mean stdev = 0.7)

T-pin-average (TP-aver) = 9.8 sec ( mean stdev = 3.8)

This means that Torpeding was accomplishing the POI placement task in 29% of the

time that the classical pin method uses, making it over three times as fast.

Furthermore, the mean standard deviation was only one fifth, showing that Torpeding

is a much more consistent way to accomplish the task.

0,0

5,0

10,0

15,0

20,0

25,0

30,0

1 2 3 4 5 6 7 8 9 10 11 12

TT-aver

TP-aver

Torpeding – A New POI Placement Method for Touch Screens 7

Discussion

As indicated from the experiment, the users strongly preferred POI-input with the

Torpeding method to the classic pin-method.

We set out to investigate our hypotheses. They were:

H1: T is faster than P

H2: T improves the accuracy of the final position compared to P

H3: T is no harder to understand than P

H4: T gives the user a higher degree of control

H5: The user likes T better than P

We can see that all five hypotheses are strongly supported.

A typical remark when rating the methods were that the user actually gave the Pin

method less favourable marks compared with Torpeding because they had now seen

that the latter was so much easier to use.

Addressing the modality issue

As was pointed out previously, Torpeding suffers from being modal. There is a way

out of this modality, however: Torpeding may be implemented by making the

crosshair temporarily visible as soon as the user starts moving the map around but

then gradually fade back into the background when map movement stops. The hot

spot of crosshair can then be used for precise indication of the POI while

moving/adjusting the map and a subsequent press on „Mark this place‟ will guarantee

that the pin hits its intended final target without using any specific modality

noticeable to the user.

Further Work

The core of the interaction challenge arises when the user by directly manipulating a

touch screen element obscures the view with the finger. This situation also happens

e.g. when one has to move the insertion point somewhere in a written text in order to

correct a typo. Alternative ways for accomplishing this inspired by Torpeding could

be worth further investigation.

One of the testers remarked that Torpeding may also be used for indicating a whole

circular area of interest, within which several POIs may be simultaneously queried

for attributes and the results presented. This could be interesting to test.

Finally, the suggested mode free method should be investigated.

8 Torpeding – A New POI Placement Method for Touch Screens

Related Work and Research

Searching for cases where torpedoing is in use on touch screens, we have only found

one case of this: The company ShortCut AS recently launched a free security app “24

timer” (24 hours) for reporting places with possible criminal activity spotted by the

user [3].

Fig. 6. Torpeding used in “24 timer” app.

Others have pointed out the problems with overloading information on mobile maps

[4] and navigation on non-touch systems. There are other recent suggestions for new

touch gestures for map interfaces [5, 6], but so far we have not seen any similar study

of Torpeding.

Conclusion

We have studied and tried out experimentally a new method, Torpeding, for input of

POI on touch screens. The method scores very high in understandability, accuracy,

speed and effectiveness and the users therefore strongly prefer it to the classical pin

method.

The results from these preliminary experiments strongly suggest that this method

should be further investigated and is likely to be a good candidate for incorporation in

future map touch screen technologies.

Credits

This work is performed as part of the Borgerkanalen project at Computas, April 2011.

Special thanks to Computas collegues Daniel Johansson and Stein Overvoll for their

views and input, and Are Refsdal for a smooth implementation of the test prototype

Torpeding – A New POI Placement Method for Touch Screens 9

on iPhone. Also thanks to chief designer Jon Eivind Hallén at Shortcut AS for

valuable input to this usability testing.

References

1. Apple Inc: iPhone Human Interface Guidelines. 2010-09-01

http://developer.apple.com/library/ios/documentation/userexperience/conceptual/mob

ilehig/MobileHIG.pdf

2. Google Maps. http://maps.google.com

3. Shortcut AS. Securitas app “24 timer” http://shortcut.no/securitas

4. Rosemarijn Looije, Guido M. te Brake, and Mark A. Neerincx. 2007. Usability

engineering for mobile maps. In Proceedings of the 4th international conference on

mobile technology, applications, and systems and the 1st international symposium on

Computer human interaction in mobile technology (Mobility '07). ACM, New York,

NY, USA, 532-539. DOI=10.1145/1378063.1378150

http://doi.acm.org/10.1145/1378063.1378150

5. Sven Kratz, Ivo Brodien, and Michael Rohs. 2010. Semi-automatic zooming for

mobile map navigation. In Proceedings of the 12th international conference on

Human computer interaction with mobile devices and services (MobileHCI '10).

ACM, New York, NY, USA, 63-72. DOI=10.1145/1851600.1851615

http://doi.acm.org/10.1145/1851600.1851615

6. Vidya Setlur, Cynthia Kuo, and Peter Mikelsons. 2010. Towards designing better

map interfaces for the mobile: experiences from example. In Proceedings of the 1st

International Conference and Exhibition on Computing for Geospatial Research

Application (COM.Geo '10). ACM, New York, NY, USA, Article 31, 4 pages.

DOI=10.1145/1823854.1823890 http://doi.acm.org/10.1145/1823854.1823890