On Tuesday, 16 November 2021, Dr Katharina Anders defended her PhD research with great success.
In her dissertation, Katharina developed methods on 4D change analysis to extract natural surface changes from near-continuous LiDAR time series of dynamic landscapes.
Congratulations, Katharina, for this excellent research – we are very proud to have you in our team and wish you all the best for the future!
![The defense took place in a hybrid format with Prof. Olaf Bubenzer, Jun.-Prof. Anna Growe, Prof. Bernhard Höfle and Prof. Maggi Kelly as members of the committee.](https://giscienceblog.geog.uni-heidelberg.de/wp-content/uploads/2021/11/pxl_20211116_175623609mp.jpg)
![4D PhD hat.](https://giscienceblog.geog.uni-heidelberg.de/wp-content/uploads/2021/11/4dandersls.gif)
Using time series-based change analysis, the developed approach takes advantage of the history of surface change by performing spatiotemporal segmentation with the concept of 4D objects-by-change (4D-OBCs). The method identifies areas in the scene where surfaces change similarly over time in sub-periods of the full time series at neighboring locations.
Key features of time series-based change analysis are:
- Removing the requirement to select and predefine periods for the analysis of changes
- Extracting change forms at different (unknown) timing, change rates, durations of change processes, and persistence of (temporary) change forms
- Separating spatially overlapping changes, which might be aggregated in bitemporal change information of a scene
This enables a generic extraction of surface changes in their varying spatial and temporal extents from large and dense 4D geospatial data.
![Concept of research in the dissertation.](https://giscienceblog.geog.uni-heidelberg.de/wp-content/uploads/2021/11/anders_research.png)
More details on Katharina’s research can be found e.g. in the publications below and on the project website:
- Anders, K., Winiwarter, L., Mara, H., Lindenbergh, R. C., Vos, S. E. & Höfle, B. (2021): Influence of Spatial and Temporal Resolution on Time Series-Based Coastal Surface Change Analysis using Hourly Terrestrial Laser Scans. ISPRS Annals of Photogrammy, Remote Sensing and Spatial Information Science, V-2-2021, 137–144. DOI: 10.5194/isprs-annals-V-2-2021-137-2021.
- Anders, K., Winiwarter, L., Mara, H., Lindenbergh, R., Vos, S.E. & Höfle, B. (2021): Fully automatic spatiotemporal segmentation of 3D LiDAR time series for the extraction of natural surface changes. ISPRS Journal of Photogrammetry and Remote Sensing. Vol. 173, pp. 297-308. DOI: 10.1016/j.isprsjprs.2021.01.015.
- Anders, K., Winiwarter, L., Lindenbergh, R., Williams, J.G., Vos, S.E. & Höfle, B. (2020): 4D objects-by-change: Spatiotemporal segmentation of geomorphic surface change from LiDAR time series. ISPRS Journal of Photogrammetry and Remote Sensing. Vol. 159, pp. 352-363. DOI: 10.1016/j.isprsjprs.2019.11.025.