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- From: "Sebastien Loriot (GeometryFactory)" <>
- To:
- Subject: Re: [cgal-discuss] bug in Loop subdivision
- Date: Wed, 23 Apr 2014 10:21:00 +0200
- Organization: GeometryFactory
On 04/23/2014 03:39 AM, Ivan Middleton wrote:
I was just comparing the results of CGAL's implementation of Loop
subdivision with my own implementation, and found a very bad error in CGAL.
On line 240 of include/CGAL/Subdivision_mask_3.h we find:
FT Cn = (FT) (5.0/8.0 - std::sqrt(3+2*std::cos(6.283/(double)n))/64.0);
The square root should instead be a squaring operation! (A much more
minor point is that it surely wouldn't hurt to use a more accurate value
for 2pi.)
This number Cn is what's called beta (or n*beta) in most references. See
for instance page 70 of
http://mrl.nyu.edu/publications/subdiv-course2000/coursenotes00.pdf
Best regards,
Ivan
Thanks for the report, it will be fixed in the next release of CGAL.
Best,
Sebastien.
- [cgal-discuss] bug in Loop subdivision, Ivan Middleton, 04/23/2014
- Re: [cgal-discuss] bug in Loop subdivision, Sebastien Loriot (GeometryFactory), 04/23/2014
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