This presentation is co-financed by the European Social Fund and the state budget of the Czech Republic

Space-Time-Cube for Visualization of Eye-tracking data

Stanislav POPELKA

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

Introduction Eye-tracking is one of the methods of usability studies and is

considered as an objective

The modern eye-trackers use contactless measurements of the visible parts of the eye and corneal reflection of direct beam of infrared light

The reflected light is recorded by camera

From analysis of the changes of corneal reflection, the point of regard is calculated

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

The human eye performs several types of movement - the most important are fixations and saccades

Qualitative information about eye movements describes the way in which the user explores the stimulus It can reveal areas of greatest interest, disruptive elements or search

tactics during answering the question

Quantitative information can be derived from eye-tracking data through metrics of fixation and saccades For example - the fixation length, saccade amplitude, fixation/saccade

ratio or AOI (Area of Interest) dwell time

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

HeatMaps and ScanPaths are common visualization methods of eye-tracking data They cannot effectively express the change of time The cause of this problem is displaying of the three-

dimensional data (X, Y, time) in two-dimensional space (X, Y) It is necessary to use spatio-temporal visualization

Visualization of eye-tracking data

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

Kraak and Ormeling (1996) describes three approaches to space-time visualization

Simple static map (ScanPath) If the static map displays complex time phenomena, it is likely that the

phenomena will overlap in the map, which can lead to loss of information.

Series of static maps (ScanPaths) It allows viewing changes in a phenomenon in several time periods For huge series of static maps, the interpretation should be difficult

Animation (of ScanPaths) Animation captures the dynamics of the space-time phenomenon

appropriately Displaying of the development of the phenomenon comprehensively for

the entire study period is not possible

Spatio-temporal visualization

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

Space-Time-Cube displays spatial and temporal component at the same time

Space–Time–Cube is the most important element in the Hägerstrand’s spatio-temporal model

Space-Time-Cube displays the map at the base of the cube (axes X and Y) while Z axis is used to represent time

Spatial and temporal components are shown together, and relationship between space and time can be revealed

Space-Time-Cube

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

Space-Time-Cube

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

Visual Analytics Toolbox (CommonGIS) Developed by Fraunhofer Institute IAIS Gennady and Natalia Andrienko

GeoTime 5 Commercial application for Space-Time-Cube Designed for geographical data Direct import from ArcGIS

Space-Time-Cube extension for open-source GIS uDig ITC in Eschende, Netherlands Team around professor Jan-Menno Kraak Unavailable at the moment

Extended Time-Geographic Framework Tools Extension for ArcGIS 9.3 compared to the above mentioned applications, this extension has less

functionality

Software for STC visualization

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

Research of map reading during solving the geographic problems Study was focused to the use of map legend Students project – students of Masters program

Total of 16 respondents 8 cartographers (KGI students after cartography course) 8 non-cartographers (zoologists, lawyers..)

Total of 19 stimuli Maps from school atlases

Unlimited time to read the question 45 seconds to answer

Short questionaire after the test

Case study

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

During the research, SMI RED 250 eye-tracker developed by SensoMotoric Instrument was used

The device allows data acquisition with frequency of 120 Hz

Point of regard of the eye, expressed with Y and Y coordinates are recorded and stored with a regular interval of 8 miliseconds

Case study

(X, Y, t)X – locationY – locationt – time …

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

Respondents automatically looks into the legend first Regardless belonging to the Cartographer/NonCartographer

group If the legend is barely legible, they spend much more

time in it One of the stimuli was a gimmick – respondents were

asked to find the coal mine in the map, but the symbol was missing in the legend

Results of case study

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

Space-Time-Cube was used for visual analysis of users interaction with maps from school atlases

Respondents were asked to quickly find areas where the flax is grown and identify it by clicking the mouse in the map

Space-Time-Cube example from the case study

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

Data modification is necessary before importing into CommonGIS

Two types of visualization of measured data in a Space-Time-Cube have been tested Visualization of trajectory made directly from raw data Visualization of fixations connected with lines (representing

saccades)

CommonGIS has not an ability to differ fixations based on their size

Space-Time-Cube in Common GIS

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

Occulus GeoTime 5 is the software for visual analysis of time series data

Possibility of connecting GeoTime with ArcMap or Microsoft Excel

Fixations can differ based on their lenght Geotime has a possibility to analyze data – find patterns,

clusters, gaps, intersections in space and time… Problems with coordinate system, units

Geotime is designed for geographical data (WGS 84) Eye-tracker produce data in Cartesian coordinate system

(1680*1050 px) GeoTime is unable to load data in miliseconds

Space-Time-Cube in GeoTime

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

Videa

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

Future plans Solve the problems with GeoTime

Use its functions for analysis

Use Space-Time-Cube for visual analysis of results from next eye-tracking tests

Comparison of 2D vs. 3D visualization

First InDOG Doctoral Conference, 29th October - 1st November 2012, Olomouc

Thank you for your attention

Stanislav Popelka

standa.popelka@gmail.com

www.geoinformatics.upol.cz/ET