bug in regionprops underlying library qhull?
Luca Fiaschi
luca.fiaschi at gmail.com
Wed Aug 22 04:41:29 EDT 2012
Hi,
I confirm the bug to be really in qhull.
I substituted the computation of the convex hull in scipy (qhull) with
another library (vigranumpy) and thins fix the problem.
If useful I might consider working on a cython implementation of the 2D
convex hull algorithm and flash a pull request.
Best
Luca
Il giorno martedì 21 agosto 2012 12:40:39 UTC+2, Luca Fiaschi ha scritto:
>
> Hi all,
> I get a strange bug trying to uses regionprops on some images.
> Computing the hull of some objects result a internal error in the qhull
> library:
> Below you can find the error and and the set of points which triggers it:
>
> Does anybody know how to fix it?
>
>
> [[ 5. 12.5]
> [ 6. 6.5]
> [ 7. 4.5]
> [ 8. 4.5]
> [ 9. 4.5]
> [ 10. 5.5]
> [ 7. 4.5]
> [ 7. 5.5]
> [ 6. 6.5]
> [ 6. 7.5]
> [ 6. 8.5]
> [ 6. 9.5]
> [ 6. 10.5]
> [ 6. 11.5]
> [ 5. 12.5]
> [ 5. 13.5]
> [ 5. 14.5]
> [ 5. 15.5]
> [ 5. 16.5]
> [ 5. 17.5]
> [ 5. 18.5]
> [ 5. 19.5]
> [ 5. 20.5]
> [ 5. 21.5]
> [ 5. 22.5]
> [ 5. 23.5]
> [ 5. 24.5]
> [ 6. 25.5]
> [ 5. 24.5]
> [ 6. 25.5]
> [ 7. 25.5]
> [ 8. 23.5]
> [ 9. 20.5]
> [ 10. 16.5]
> [ 9. 4.5]
> [ 10. 5.5]
> [ 10. 6.5]
> [ 10. 7.5]
> [ 10. 8.5]
> [ 10. 9.5]
> [ 10. 10.5]
> [ 10. 11.5]
> [ 10. 12.5]
> [ 10. 13.5]
> [ 10. 14.5]
> [ 10. 15.5]
> [ 10. 16.5]
> [ 9. 17.5]
> [ 9. 18.5]
> [ 9. 19.5]
> [ 9. 20.5]
> [ 8. 21.5]
> [ 8. 22.5]
> [ 8. 23.5]
> [ 7. 24.5]
> [ 7. 25.5]
> [ 5. 13.5]
> [ 6. 7.5]
> [ 7. 5.5]
> [ 8. 5.5]
> [ 9. 5.5]
> [ 10. 6.5]
> [ 7. 5.5]
> [ 7. 6.5]
> [ 6. 7.5]
> [ 6. 8.5]
> [ 6. 9.5]
> [ 6. 10.5]
> [ 6. 11.5]
> [ 6. 12.5]
> [ 5. 13.5]
> [ 5. 14.5]
> [ 5. 15.5]
> [ 5. 16.5]
> [ 5. 17.5]
> [ 5. 18.5]
> [ 5. 19.5]
> [ 5. 20.5]
> [ 5. 21.5]
> [ 5. 22.5]
> [ 5. 23.5]
> [ 5. 24.5]
> [ 5. 25.5]
> [ 6. 26.5]
> [ 5. 25.5]
> [ 6. 26.5]
> [ 7. 26.5]
> [ 8. 24.5]
> [ 9. 21.5]
> [ 10. 17.5]
> [ 9. 5.5]
> [ 10. 6.5]
> [ 10. 7.5]
> [ 10. 8.5]
> [ 10. 9.5]
> [ 10. 10.5]
> [ 10. 11.5]
> [ 10. 12.5]
> [ 10. 13.5]
> [ 10. 14.5]
> [ 10. 15.5]
> [ 10. 16.5]
> [ 10. 17.5]
> [ 9. 18.5]
> [ 9. 19.5]
> [ 9. 20.5]
> [ 9. 21.5]
> [ 8. 22.5]
> [ 8. 23.5]
> [ 8. 24.5]
> [ 7. 25.5]
> [ 7. 26.5]
> [ 4.5 13. ]
> [ 5.5 7. ]
> [ 6.5 5. ]
> [ 7.5 5. ]
> [ 8.5 5. ]
> [ 9.5 6. ]
> [ 6.5 5. ]
> [ 6.5 6. ]
> [ 5.5 7. ]
> [ 5.5 8. ]
> [ 5.5 9. ]
> [ 5.5 10. ]
> [ 5.5 11. ]
> [ 5.5 12. ]
> [ 4.5 13. ]
> [ 4.5 14. ]
> [ 4.5 15. ]
> [ 4.5 16. ]
> [ 4.5 17. ]
> [ 4.5 18. ]
> [ 4.5 19. ]
> [ 4.5 20. ]
> [ 4.5 21. ]
> [ 4.5 22. ]
> [ 4.5 23. ]
> [ 4.5 24. ]
> [ 4.5 25. ]
> [ 5.5 26. ]
> [ 4.5 25. ]
> [ 5.5 26. ]
> [ 6.5 26. ]
> [ 7.5 24. ]
> [ 8.5 21. ]
> [ 9.5 17. ]
> [ 8.5 5. ]
> [ 9.5 6. ]
> [ 9.5 7. ]
> [ 9.5 8. ]
> [ 9.5 9. ]
> [ 9.5 10. ]
> [ 9.5 11. ]
> [ 9.5 12. ]
> [ 9.5 13. ]
> [ 9.5 14. ]
> [ 9.5 15. ]
> [ 9.5 16. ]
> [ 9.5 17. ]
> [ 8.5 18. ]
> [ 8.5 19. ]
> [ 8.5 20. ]
> [ 8.5 21. ]
> [ 7.5 22. ]
> [ 7.5 23. ]
> [ 7.5 24. ]
> [ 6.5 25. ]
> [ 6.5 26. ]
> [ 5.5 13. ]
> [ 6.5 7. ]
> [ 7.5 5. ]
> [ 8.5 5. ]
> [ 9.5 5. ]
> [ 10.5 6. ]
> [ 7.5 5. ]
> [ 7.5 6. ]
> [ 6.5 7. ]
> [ 6.5 8. ]
> [ 6.5 9. ]
> [ 6.5 10. ]
> [ 6.5 11. ]
> [ 6.5 12. ]
> [ 5.5 13. ]
> [ 5.5 14. ]
> [ 5.5 15. ]
> [ 5.5 16. ]
> [ 5.5 17. ]
> [ 5.5 18. ]
> [ 5.5 19. ]
> [ 5.5 20. ]
> [ 5.5 21. ]
> [ 5.5 22. ]
> [ 5.5 23. ]
> [ 5.5 24. ]
> [ 5.5 25. ]
> [ 6.5 26. ]
> [ 5.5 25. ]
> [ 6.5 26. ]
> [ 7.5 26. ]
> [ 8.5 24. ]
> [ 9.5 21. ]
> [ 10.5 17. ]
> [ 9.5 5. ]
> [ 10.5 6. ]
> [ 10.5 7. ]
> [ 10.5 8. ]
> [ 10.5 9. ]
> [ 10.5 10. ]
> [ 10.5 11. ]
> [ 10.5 12. ]
> [ 10.5 13. ]
> [ 10.5 14. ]
> [ 10.5 15. ]
> [ 10.5 16. ]
> [ 10.5 17. ]
> [ 9.5 18. ]
> [ 9.5 19. ]
> [ 9.5 20. ]
> [ 9.5 21. ]
> [ 8.5 22. ]
> [ 8.5 23. ]
> [ 8.5 24. ]
> [ 7.5 25. ]
> [ 7.5 26. ]]
> QH6228
> Qhull internal error (qh_findbestlower): all neighbors of facet 12 are
> flipped or upper Delaunay.
> Please report this error to qhull_bug at qhull.org with the input and all of
> the output.
> ERRONEOUS FACET:
> - f12
> - flags: top simplicial upperDelaunay
> - normal: -0.965 -0.1942 0.1764
> - offset: 6.243641
> - vertices: p138(v7) p224(v3) p112(v0)
> - neighboring facets: f6 f28 f13
>
> While executing: | qhull d Qz Qbb Qt
> Options selected for Qhull 2010.1 2010/01/14:
> run-id 1565793501 delaunay Qz-infinity-point Qbbound-last
> Qtriangulate
> _pre-merge _zero-centrum Pgood _max-width 22 Error-roundoff 3.7e-14
> _one-merge 2.6e-13 _near-inside 1.3e-12 Visible-distance 7.4e-14
> U-coplanar-distance 7.4e-14 Width-outside 1.5e-13 _wide-facet 4.4e-13
> Last point added to hull was p132.
>
> At error exit:
>
> Delaunay triangulation by the convex hull of 225 points in 3-d:
>
> Number of input sites and at-infinity: 11
> Number of nearly incident points: 9
> Number of Delaunay regions: 0
>
> Statistics for: | qhull d Qz Qbb Qt
>
> Number of points processed: 11
> Number of hyperplanes created: 31
> Number of facets in hull: 18
> Number of distance tests for qhull: 1324
>
>
> precision problems (corrected unless 'Q0' or an error)
> 8 coplanar points during partitioning
>
>
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