FeatureIds are the unique values given to each feature in the microstructure. From a historical polycrystalline perspective, the featureId is the “Grain Id”. FeatureIds are generated from the Segmentation filters. FeatureIds link data about each feature (its size, shape, axis, average Euler Angle) to the cell data, i.e., if you give me a specific voxel, by using its featureId I can tell you which feature that voxel belongs to, and then tell you all about that specific feature.
Mike Jackson
BlueQuartz Software