OpenLB UseCase C

In UseCase A and UseCase B, we demonstrated how to create simulations based on either geometric models or measurement data. This time, we focus on how to analyze these simulation results.

To get started, open the designated workspace for use-case C in Voreen.

Once you're in the application mode, the interface will appear as follows:

Operations in the Properties panel:

• Input Ensemble Data:
  Load the ensemble data generated in either UseCase A or UseCase B.
• Input Segmentation:
  Optionally, load the segmentation results from UseCase B, if available.
• Similartiy Matrix & Similarity Plot:
  Configure a multi-field similarity metric and apply dimensionality reduction as described in the publication: (https://doi.org/10.2312/vcbm.20201180).
• Ensemble Variance:
  Adjust the transfer function to explore variance across the ensemble.

Similarity Results

Tuning the settings in the Properties panel can produce varying results. Here is an example visualization:

Interaction with Analysis Results

The interface presents a split view with four panels, enabling interactive exploration of the data:

• Top Left:
  Select two simulation instances for direct comparison. This happens by left-clicking for example the measurement and right-clicking one ensemble member.
• Top Right:
  Examine the variance between the selected instances. This can either be shown as voxel-wise variance or as a connected component analysis of regions exhibiting the highest variance. Furthermore, it is possible to compare the streamlines of both selected members.
• Bottom Left:
  Investigate differences in vector magnitude between the selected instances. A blue plane allows interactive slicing of the volume, which corresponds to the view shown in the bottom-right panel.
• Bottom Right:
  Display the values along the selected cutting plane. Hovering over this view allows for precise exploration of local differences, with the corresponding location indicated in the bottom-left panel.

Ensemble Comparison and Analysis Tasks

Use Case C enables detailed insights into the simulation ensemble and its alignment with measurement data. Key analysis tasks include for instance:

• Parameter Sensitivity Analysis:
  Explore how different parameter configurations affect the simulation output. Determine which parameters yield results most consistent with the measurement data.
• Region of Interest Detection:
  Use variance and magnitude visualizations to identify spatial regions with significant deviations. For instance, if a region exhibits both high magnitude differences and large spatial extent, this may indicate that the simulation is not accurately modeling the measured phenomenon.