Local feature size: Difference between revisions

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Created page with 'Local feature size is a computer graphics term. Before the exact definition, we should give another concept called medial axis. Medial axis of a manifold M is a po...'
 
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'''Local feature size''' isrefers ato several related concepts in [[computer graphics]] term.and [[computational Beforegeometry]] thefor exactmeasuring definition,the wesize shouldof givea anothergeometric conceptobject callednear mediala axisparticular point.
 
Medial axis of a manifold M is a point set such that each point in the set at least has two closest points in M.
*Given a [[differentiable manifold|smooth manifold]] <math>M</math>, the local feature size at any point <math>x \in M</math> is the distance between <math>x</math> and the [[medial axis]] of <math>M</math>.<ref>{{cite journal | doi=10.1007/PL00009475 | first1=Nina | last1=Amenta | author1-link = Nina Amenta | first2=Marshall | last2=Bern | title=Surface reconstruction by Voronoi filtering | journal=Discrete and Computational Geometry | year=1999 | issue=4 | pages= 481–504 | volume=22| url=https://escholarship.org/content/qt4rc7z0d1/qt4rc7z0d1.pdf?t=ptt31s | doi-access=free }}</ref>
The local feature size at x in M, denoted as LFS(x), is the distance from x to the medial axis of M.
*Given a [[planar straight-line graph]], the local feature size at any point <math>x</math> is the radius of the smallest closed ball centered at <math>x</math> which intersects any two disjoint features (vertices or edges) of the graph.<ref>{{cite journal | doi=10.1006/jagm.1995.1021 | first=Jim | last=Ruppert | title=A Delaunay refinement algorithm for quality 2-dimensional mesh generation | journal=Journal of Algorithms | year=1995 | issue=3 | pages= 548–585 | volume=18}}</ref>
 
{{multiple image
| direction = horizontal
| align = center
| header = Definitions of local feature size. In each case, the local feature size at the blue points is the radius of the associated blue circle.
| image1 = Medial_lfs.svg
| width1 = {{#expr: (250 * 1276 / 886) round 0}}
| alt1 = Medial axis-base definition.
| caption1 = Local feature size for a smooth manifold (black) with medial axis (red).
| image2 = Ruppert_lfs.svg
| width2 = {{#expr: (250 * 1205 / 780) round 0}}
| alt2 = Planar straight line graph-based definition.
| caption2 = Local feature size for a planar straight-line graph.
}}
 
==See also==
*[[Nearest neighbour function]]
 
== References ==
{{Reflist}}
 
[[Category:Geometric algorithms]]