The Groupwise Medial Axis Transform for Fuzzy Skeletonization and Pruning
Bibliographic record
Abstract
Medial representations of shapes are useful due to their use of an object-centered coordinate system that directly captures intuitive notions of shape such as thickness, bending, and elongation. However, it is well known that an object's medial axis transform (MAT) is unstable with respect to small perturbations of its boundary. This instability results in additional, unwanted branches in the skeletons, which must be pruned in order to recover the portions of the skeletons arising purely from the uncorrupted shape information. Almost all approaches to skeleton pruning compute a significance measure for each branch according to some heuristic criteria, and then prune the least significant branches first. Current approaches to branch significance computation can be classified as either local, solely using information from a neighborhood surrounding each branch, or global, using information about the shape as a whole. In this paper, we propose a third, groupwise approach to branch significance computation. We develop a groupwise skeletonization framework that yields a fuzzy significance measure for each branch, derived from information provided by the group of shapes. We call this framework the Groupwise Medial Axis Transform (G-MAT). We propose and evaluate four groupwise methods for computing branch significance and report superior performance compared to a recent, leading method. We measure the performance of each pruning algorithm using denoising, classification, and within-class skeleton similarity measures. This research has several applications, including object retrieval and shape analysis.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.006 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".