Original Post
Hello
Could someone explain me how can I compute a thight OBB for a model (ex: character keyframe), or maybe point me to some docs of code where I can learn this?
Thanks in advance,
Oscar
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computing an OBB how?
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tight fitting OBBs is more complicated than it first looks. For the best results,
1) compute a convex hull of your vertices (look at qhull on the net), or take the vertices, or take the centre of your triangles (that or srtaight vertices should be enough for a character animation).
2) compute the mean (the 'centre') of the hull/vertices/centre of triangles.easy.
3) compute the covariance matrix (in the paper) of the hull/vertices/centre of triangles. not too difficult.
4) find the eigen vectors of the covariance matrix (which is symmetric). Hard work.
5) normalise the vectors (easy).
ftp://ftp.cs.unc.edu/pub/users/manocha/PAPERS/COLLISION/obb.ps.gz
and one of the best sites for collision detection (also related to other stuff),
http://www.magic-software.com/Documentation.html
look at documentation, eigen systems for 3x3 matrices, eigen solver for symmetric matrices, that with the obb.ps above. The eigen source code should also be available at magic-software.com
[edited by - oliii on April 7, 2003 8:24:33 AM]
1) compute a convex hull of your vertices (look at qhull on the net), or take the vertices, or take the centre of your triangles (that or srtaight vertices should be enough for a character animation).
2) compute the mean (the 'centre') of the hull/vertices/centre of triangles.easy.
3) compute the covariance matrix (in the paper) of the hull/vertices/centre of triangles. not too difficult.
4) find the eigen vectors of the covariance matrix (which is symmetric). Hard work.
5) normalise the vectors (easy).
ftp://ftp.cs.unc.edu/pub/users/manocha/PAPERS/COLLISION/obb.ps.gz
and one of the best sites for collision detection (also related to other stuff),
http://www.magic-software.com/Documentation.html
look at documentation, eigen systems for 3x3 matrices, eigen solver for symmetric matrices, that with the obb.ps above. The eigen source code should also be available at magic-software.com
[edited by - oliii on April 7, 2003 8:24:33 AM]
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