Rank: 44 based on 1096 downloads (last 30 days) and 16 files submitted
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David Legland

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Company/University
INRA, France

Personal Profile:

Research engineer in computer sciences, more precisely image processing and applied statistics.

Interested in image analysis, geometrical modelling, image registration problems, estimation in discrete images, and polyhedral reconstruction.

web page:
http://www.pfl-cepia.inra.fr/ (in french)
See also:
http://matgeom.sourceforge.net
http://matimage.sourceforge.net


 

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Files Posted by David Legland View all
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(last 30 days)
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27 Oct 2014 Screenshot geom2d Geometry library for matlab. Performs geometric computations on points, lines, circles, polygons... Author: David Legland color, mathematics, computational geometr..., toolbox, geometry, display 270 61
  • 4.04762
4.0 | 24 ratings
13 Oct 2014 Screenshot geom3d Library to handle 3D geometric primitives: create, intersect, display, and make basic computations Author: David Legland potw, pick of the week, 3d, geometric computing, plane, toolbox 373 99
  • 4.86111
4.9 | 40 ratings
17 Sep 2014 Screenshot Geometric measures in 2D/3D images Measure of geometric parameters in 2D or 3D images (surface area, perimeter, Euler Number...) Author: David Legland image analysis, particle analysis, region properties, minkowski functionals, intrinsic volumes, geometric measures 71 9
  • 5.0
5.0 | 3 ratings
02 Sep 2014 Screenshot Feret diameter and oriented box Compute Feret diameters and oriented bounding box from label image Author: David Legland feret diameter, image processing, label image, particle analysis, oriented box 37 1
  • 5.0
5.0 | 5 ratings
25 Jun 2014 Screenshot Table class A class for handling data tables together with row and column labels Author: David Legland statistics, data table, data exploration, data import, oop 20 0
Comments and Ratings by David Legland View all
Updated File Comments Rating
02 Dec 2014 geom2d Geometry library for matlab. Performs geometric computations on points, lines, circles, polygons... Author: David Legland

Hi William,
functions meshVolume and polygonArea depends on the face (or vertices) orientation. If all faces are oriented outwards, the volume will be positive. If all facets are orieted inwards, you will obtain the negative value of the volume. Just be careful to ensure faces orientation is consistent (use checkMeshAdjacentFaces for example)

21 Nov 2014 geom3d Library to handle 3D geometric primitives: create, intersect, display, and make basic computations Author: David Legland

Hi Matthew,
you can check the 'intersectLineMesh3d' function. It uses line representation in the form [x0 y0 z0 dx dy dz], where (x0,y0,z0) is the origin of the line and (dx,dy,dz) represents a direction vector of the line. Meshes are represented as vertices + faces, with vertices being Nv-by-3 array of vertex coordinates, and faces being either Nf-by-3, Nf-by-4 array of vertex indices, or cell arrays of vertex indices allowing more generic faces.

There is a function for reading meshes in OFF format ('readMesh_off'). Otherwise, you may want to check other contributions to import (and eventually convert) you files. See graph toolbox for example.

27 Oct 2014 geom2d Geometry library for matlab. Performs geometric computations on points, lines, circles, polygons... Author: David Legland

Hi Jasper,
thanks for pointing out the bug! I have released a new version that should fix it. Tell me if there are still problems.
David

13 Oct 2014 geom3d Library to handle 3D geometric primitives: create, intersect, display, and make basic computations Author: David Legland

@Abdulrahman,
sorry, I missed your comment... There is no direct function for testing if a point is inside a 3D circle. What you can do is 1) extract the plane containing the circle, 2) test if the point belong to the plane, and 3) if yes, compute coordinates of point in 2D plane, and test if the 2D point is within the 2D circle (you may need geom2d also).
hope this helps ?
regards

13 Oct 2014 geom3d Library to handle 3D geometric primitives: create, intersect, display, and make basic computations Author: David Legland

Hi Jin,
yes, there aer numerical precision issus with this function... I have submitted a new version, that is more tolerant for finding intersection at edges of faces. However sometimes too many intersections are obtained. You can remove them by using the 'mergeClosePoints' function from the geom2d toolbox.
regards,
David

Comments and Ratings on David Legland's Files View all
Updated File Comment by Comments Rating
22 Dec 2014 geom3d Library to handle 3D geometric primitives: create, intersect, display, and make basic computations Author: David Legland Johannes

Hi David,
thanks for your quick reply. I am using the following code now:

K = minConvexHull(tmpVerts,myEPS)';
tmpInd = unique(cell2list(K));
[K, vol] = minConvexHull(tmpVerts(tmpInd,:),myEPS);

I modified your minConvexHull to pass the volume from qhull and cell2list is cell2mat essentially.

Concerning the volume: I guess it should be

abs(det(tetra) / 6)

in your meshVolume function? Otherwise, I do not get positive volumes in general.

17 Dec 2014 geom3d Library to handle 3D geometric primitives: create, intersect, display, and make basic computations Author: David Legland Dexter

Hej, David:

Thanks for your sharing of this wonderful library.
I am working on draw a polyhedron, the first Brillouin Zone in Physics. Which specific function should I look in this library for my purpose?

Best wishes!

02 Dec 2014 geom2d Geometry library for matlab. Performs geometric computations on points, lines, circles, polygons... Author: David Legland David Legland

Hi William,
functions meshVolume and polygonArea depends on the face (or vertices) orientation. If all faces are oriented outwards, the volume will be positive. If all facets are orieted inwards, you will obtain the negative value of the volume. Just be careful to ensure faces orientation is consistent (use checkMeshAdjacentFaces for example)

01 Dec 2014 geom2d Geometry library for matlab. Performs geometric computations on points, lines, circles, polygons... Author: David Legland William

I seem to get a negative volume using the meshVolume function...
I'm trying to calculate the volume of a bendy open ended cylinder, using the faces and vertices generated from an isosurface patch. Any thoughts?

22 Nov 2014 geom3d Library to handle 3D geometric primitives: create, intersect, display, and make basic computations Author: David Legland matteo

Hi David,

thank you so much for your work (the intersectLineSphere), I am working on my master thesis and you really saved me.

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