3D terrain visualization – Dual map

The experiment was performed for investigating the differences between user cognition of classical 2D visualization with contour lines and perspective 3D view. Eye-tracking experiment was supplemented by online questionnaire focused on maps understandability, suitability and aesthetics. Results of the questionnaire shows, that the majority of participants prefer 3D visualization.

Eye-tracking experiment was designed as a pair of maps in one stimuli. One shows 2D visualization, the other 3D visualization. No significant differences between user preferences of 2D and 3D visualization were found, but the results were influenced with the order of the maps in the stimuli. Because of that another experiment (3D terrain visualization – Double map) was designed.

Methods

Procedure

Before each stimuli, the respondents had 30 seconds to read and remember the task. After that, the fixation cross was presented for 600 ms to ensure that all respondents started from the center of the stimuli. Then, the stimuli with the map was projected for 60 seconds. Respondents had to answer the question with use of mouse click directly into the map. To avoid the influence of the location of maps within the stimulus (left, right), two groups of users were tested. Stimuli for both groups were the same, but the position of 2D and 3D maps within the stimulus was changed. On the first one, 2D map was presented on the left side, 3D on the right. On the second version vice versa. 

Independent variables

In the DualMap experiment, stimuli were designed as a pair of maps in 2D and 3D side by side. The aim was to reveal, which kind of visualization will be preferred when searching for answer on spatial query.

Stimuli

Total of eleven image stimuli were used in the experiment. Terrain visualizations (stimuli 4-8) were created in Esri ArcMap and ArcScene. The work of Savage et al. (2004) was used as an inspiration. 

 Participants

Total of 40 respondents had participated within this eye-tracking study. Half of them were selected from the group of undergraduate students, who already attended cartography course. The rest of them were selected from students of different field of study than cartography. Differences between cartographers and non-cartographers can be investigated

Apparatus

For the study, remote eye-tracking device SMI RED 250, developed by SensoMotoric Instruments, was used. This device was operating at frequency of 120 Hz. 

 Analyses

For the analysis of DualMap experiment, the “Dwell Time” metric was chosen. It was used for comparison of attention distributed between targets. Within the stimuli only two AOI representing 2D and 3D map were marked. The statistical analysis was then used to examine whether there is a difference between how users viewed part of the stimulus with 3D Map and 2D map. On the significance level α = 0.05 no statistically significant difference for any of the studied stimulus was found. 

In the next step, it was tested, if the value of Dwell Time is not influenced by order of the maps in the stimuli. Generally speaking, the image on the left side should be preferred more, because participants are used to read text from the left side. Differences between dwell time values based on the order of maps in the stimuli were also tested with use of Wilcoxon rank sum test. There was found a statistically significant difference in the half of observations. Order of maps in the stimuli influenced the value of Dwell time in stimuli 4, 6 and 8.

Conclusion

The results indicated, that DualMap experiment design was not suitable, because respondents cognition was influenced with the order of the maps in the stimuli more than by differences between 2D and 3D visualization. For further analyses, use of SingleMap experiment should be more appropriate.

Outputs

Popelka, S., & Brychtova, A. (2013). Eye-tracking study on different perception of 2D and 3D terrain visualisation. Cartographic Journal, 50(3), 240-246. 

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