Effectively, z = 0 is defined for all points. This Node editor is only available in the nightly version of ParaView and needs to be enabled using the Manage Plugins… menu that we saw earlier.Although our chosen domain is in 2D, the function in ParaView that converts our table to a structured grid requires three coordinates. We may have a look at the recently added Node editor to replace / complement the original Pipeline browser. Figure 9: TTK Manifold checker, non manifold vertices, edges and faces are shown in red.Īs a side note, using TTK often involves large pipelines. Its use is highlighted in this example, and illustrated in Figure 9. This can be done using the TTK Manifold checker filter. For the moment, you also need to check if your data is manifold. For the simplicial complex part, the Thetrahedralize and Clean to Grid filters should be enough to ensure you only have valid cells. When using TTK, as explained in Section 2, you need to check that your data forms a manifold simplicial complex. Figure 8 presents another example where we can distinguish phalanges. If you want to change the coarseness of the extracted feature, you can play with the “Lower Threshold” of the Persistence Threshold filter in the Pipeline. You can find a more detailed version of the pipeline in the tutorial that was given at IEEE VIS 2020: (time-code 01:38:45) and in the example website. Finally, we use this segmentation to extract areas attached to maxima. With the TTK FTM Tree filter, we compute the contour tree along with the corresponding segmentation (cf. Then, the filtered diagram is used to configure a topological simplification of the initial domain, resulting in a new version where the noise has been removed. With a threshold on the persistence, we filter this diagram to only keep the most prominent features (see the Properties panel on the left of Figure 7). On this diagram, each bar corresponds to one feature and the persistence (the height) of the bar is a measure of the robustness of this feature. In the first part of the pipeline, we use a topological abstraction named the persistence diagram to extract the data set features. Due to small fluctuations, especially in the air, this dataset is noisy. Points with the highest density correspond to bones, and the lowest density is the air around the foot. This state file reads the dataset ctBones.vti, containing a human foot scan with the density of matter represented as point scalars. For a more complete introduction to Topological Data Analysis, you can find this IEEE Vis 2020 Tutorial: (Introduction starts at 00:06:55).įigure 7: ctBones.pvsm, segmentation based on region of maximum density (bones) on a CT scan using TTK. It is for example possible to hierarchically simplify the scalar field using the relationship emphasized in Figure 6. The toolkit also comes with filters to work with these abstractions. the relationship between various scalar fields (Continuous scatter-plot).the temporal evolution of features (Planar Graph Layout).
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