1. MSc thesis in Geography, with Major in Geographic Information Science
Visualising multivariate spatio-temporal data Design and evaluation of an open source software environment based on 3D DEMs and multiple linked views
MSc thesis in Geography,
with Major in Geographic Information Science
June 2010 – May 2011
Marco Bernasocchi
Advisor: Dr. Arzu Çöltekin
Co-advisor: Dr. Stephan Gruber
Faculty advisor: Prof. Dr. Sara Fabrikant

2. Visualising multivariate spatio-temporal data
Program
Context
Research questions
Implementation
Results
Evaluation
Conclusion
Visualising multivariate spatio-temporal data

3. Visualising multivariate spatio-temporal data
Context | Research questions | Implementation | Results | Evaluation | Conclusion
Motivation
The 3G Section of GIUZ is collecting and generating with numerical models high resolution multivariate spatio-temporal datasets
Data to be effectively analysed to gain valuable insight over the soil/ice changes over time
Challenges in analysis of big spatio-temporal datasets without proper visualisations
The Large Hadron Collider will produce roughly 15 petabytes (15 million gigabytes) of data annually – enough to fill more than 1.7 million dual-layer DVDs a year!
Visualising multivariate spatio-temporal data

4. Current visualisation
Context | Research questions | Implementation | Results | Evaluation | Conclusion
Current visualisation
Current visualisation/analysis using ENVI:
Linked scatter-plot, pixel map and time-slider
The analysis by moving the time cursor
Direct comparison by two ENVI sessions
Visualising multivariate spatio-temporal data

5. Visualising multivariate spatio-temporal data
Context | Research questions | Implementation | Results | Evaluation | Conclusion
Research questions
How can a 3D terrain be successfully linked to multivariate spatio-temporal data visualisations?
Which temporal data visualisations would make our system intuitive, efficient and easy to use with the specific type of data (i.e. temporal and cyclic data) generated by environmental monitoring projects?
How can data anomalies and outliers be visually correlated to the topography?
Does adding the surface topography (on a DEM), in comparison to more abstract visualisations (various 2D or 3D plots) make a (positive) difference in inference making in environmental (and similar) monitoring projects?
Visualising multivariate spatio-temporal data

6. Visualising multivariate spatio-temporal data
Context | Research questions | Implementation | Results | Evaluation | Conclusion
User centred design
User tasks analysis
Search for temporal patterns at a given location in cyclic data
Search for spatial patterns at a given time
Search for outliers and data anomalies
Interpret data clusters in a scattergram and find correlation to space and time
Brainstorming sessions with Arzu and Stephan
Visualising multivariate spatio-temporal data

7. Visualising multivariate spatio-temporal data
Context | Research questions | Implementation | Results | Evaluation | Conclusion
User centred design
Focus Group with five expert users
A globe-like terrain model module with stereo 3D capabilities
A visualisation framework with at least Time vs. value plot and 3D Helix visualisation [Tominski et al., 2005]
A scattergram tool with a functionality to plot the values on the globe
exploit the “group effect” (Carey, 1994).
“changing” or “cascading” effect
Visualising multivariate spatio-temporal data

8. Visualising multivariate spatio-temporal data
Context | Research questions | Implementation | Results | Evaluation | Conclusion
Architecture
GPL Quantum GIS plugins (Python and C++)
Multiple views (independent modules) with brushing and linking (select in one view highlight in all) [Rogowitz et al., 1996]
Overview – zoom and filter – details on demand [Shneiderman, 1996]
Opensource because>
Sharing the work
Better code quality
Adaptabilitz of core code
Multiple modules so that it is expandeable
O-Z-F for example in helix, by clicking on the helix after zooming in
Visualising multivariate spatio-temporal data

9. Visualising multivariate spatio-temporal data
Context | Research questions | Implementation | Results | Evaluation | Conclusion
Globe
Visualising multivariate spatio-temporal data

10. Visualising multivariate spatio-temporal data
Context | Research questions | Implementation | Results | Evaluation | Conclusion
Globe stereo
Visualising multivariate spatio-temporal data

11. Visualisation framework
Context | Research questions | Implementation | Results | Evaluation | Conclusion
Visualisation framework
Visualising multivariate spatio-temporal data

12. Visualising multivariate spatio-temporal data
Context | Research questions | Implementation | Results | Evaluation | Conclusion
Timeplot
Visualising multivariate spatio-temporal data

13. Visualising multivariate spatio-temporal data
Context | Research questions | Implementation | Results | Evaluation | Conclusion
Timeplot
Visualising multivariate spatio-temporal data

14. Visualising multivariate spatio-temporal data
Context | Research questions | Implementation | Results | Evaluation | Conclusion
HelixView
Visualising multivariate spatio-temporal data

15. Visualising multivariate spatio-temporal data
Context | Research questions | Implementation | Results | Evaluation | Conclusion
HelixView
Visualising multivariate spatio-temporal data

16. Visualising multivariate spatio-temporal data
Context | Research questions | Implementation | Results | Evaluation | Conclusion
Pilot study
Qualitative expert interviews
Five participants with maximized heterogeneity
Semi structured interview (1.5 hour each)
Content and interface oriented tasks
Scenarios with integrated SEE [satisfaction, efficiency, effectiveness] metrics [Fuhrmann 2005, Tobon 2005]
Close and open ended questions
This slide may create discussion. However, designing proper user studies will not fit into the time. This is WHY you call this a 'pilot' study (you can bold the word pilot ;). You will keep the sample size small, test it over a small set of tasks, and the rest should 'future work'.
If people are too stuck with the evaluation, you can argue that the implementation itself in the way it flexibly brings together different visualization and analysis modules makes the study original and 'generic' and the pilot study is only complementary because you have only that much time in an MSc study :)
Visualising multivariate spatio-temporal data

17. Visualising multivariate spatio-temporal data
Context | Research questions | Implementation | Results | Evaluation | Conclusion
Analysis
Favourites tools: combination of scattergram and
time plot
Globe was showstopper meanwhile partly fixed
Performance and stabilitz are the main problem
Code quality is defined on known bugs
Visualising multivariate spatio-temporal data

18. Research questions answers
Context | Research questions | Implementation | Results | Evaluation | Conclusion
Research questions answers
RQ 1: Linking and Brushing works with Globe as well
RQ 2: More classical visualisations might be easier when dealing with unknown data. Novel visualisation need training with known data. A combination of the two is welcome
RQ 3: Back referencing scattergram data to globe is very intuitive
How can a 3D terrain be successfully linked to multivariate spatio-temporal data visualisations?
Which temporal data visualisations would make our system intuitive, efficient and easy to use with the specific type of data (i.e. temporal and cyclic data) generated by environmental monitoring projects?
How can data anomalies and outliers be visually correlated to the topography?
Does adding the surface topography (on a DEM), in comparison to more abstract visualisations (various 2D or 3D plots) make a (positive) difference in inference making in environmental (and similar) monitoring projects?
Visualising multivariate spatio-temporal data

19. Visualising multivariate spatio-temporal data
Context | Research questions | Implementation | Results | Evaluation | Conclusion
Critics
Other solution possible with other strengths and weakness
Formal quantitative study needed
Usefulness of stereo (and RQ 4) needs to be researched
Expert interviews would have been better earlier to allow more feedback based debugging
Many Other visualisation tools
Visualising multivariate spatio-temporal data

20. Questions!? Thanks a lot for your attention
[bernawebdesign.ch | opengis.ch]
Visualising multivariate spatio-temporal data