RE: [Algorithms] Generating uv coordinates which follow a shape
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RE: [Algorithms] Generating uv coordinates which follow a shape
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From: Doug R. <DR...@nv...> - 2004-06-23 22:12:39
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If you have connectivity, you can optimize the texture coordinates = afterwards to reduce distortion. =20 It is described here: http://www.loria.fr/~levy/Papers/2002/s2002_lscm.pdf http://www.loria.fr/~levy/Galleries/LSCM/index.html Hugues Hoppe also has done work in this area. http://research.microsoft.com/copyright/accept.asp?path=3Dhttp://research= .microsoft.com/~hoppe/mcgim.pdf&pub=3D18 -Doug -----Original Message----- From: gda...@li... = [mailto:gda...@li...]=20 Sent: Tuesday, June 22, 2004 4:54 PM To: gda...@li... Subject: RE: [Algorithms] Generating uv coordinates which follow a shape Has anyone else implemented this paper? I made an implementation in a max modifier, and the results are = promising, but far from what I expect. The orthogonality constraint = doesn't seem to be that influential. And scaling the constraints with an = "influence" value has no effect whatsoever. I guess I am either missing something or I need to make a "good" start = uv assignment before running the algo on it (right now I put all = "unknown" uvs at 0,0. Dunno if that s a good plan). Also increasing the = number of iterations doesn't help at all. If anyone would care to shed some light on this or help me out, it would = greatly be appreciated ;) Here is a screenshot : http://users.pandora.be/ir_fuel/uv_problem.jpg Joris > -----Original Message----- > From: gda...@li... > [mailto:gda...@li...] On=20 > Behalf Of Ga=EBl LEQUEUX > Sent: Friday, April 30, 2004 11:17 > To: gda...@li... > Subject: RE: [Algorithms] Generating uv coordinates which=20 > follow a shape >=20 >=20 > Hi, > A few years ago I wrote a MAX plugin that did exactly what > your are trying to do :) (mapping a flag for example). Yes,=20 > border UV was the easy part, for the other points, I first=20 > assigned UV with a simple projection and then I used Discrete=20 > Smooth Interpolation (iterative relaxation) to equalize texel=20 > density. Here is where you'll find what you need :=20 > http://www.loria.fr/~levy/Papers/1998/s1998_textures.pdf >=20 > Ga=EBl >=20 >=20 > -----Message d'origine----- > De=A0: gda...@li... > [mailto:gda...@li...] De la > part de Joris Mans Envoy=E9=A0: vendredi 30 avril 2004 01:54 =C0=A0:=20 > gda...@li... > Objet=A0: [Algorithms] Generating uv coordinates which follow a shape >=20 > Hi >=20 > I ve been fiddling with this for some days, but don't seem to > come up with a "general" solution. The problem is the=20 > following: Assume a planar mesh. I want to define uvs over=20 > that mesh in the following way. I have 4 corner vertices on=20 > the mesh which will contain mapping coords 0,0 1,0 1,1 =20 > 0,1. The uvs on the border of the mesh are calculated by=20 > iterating over the border and using the piecewise distance of=20 > each line segment to define the interpolated values: >=20 > Mapping[ k ]=20 > =3D Mapping[ corner_index ]=20 > + ( Mapping[ next_corner_index ] - Mapping[ corner_index > ] )=20 > * ( distance(corner_index,k) / > distance(corner_index,next_corner_index) >=20 > Whereby distance just sums up all the edge lengths from one > vertex upto another, following the border of the mesh. >=20 > Now this was the easy part, the hard part is assigning the > uvs to the non-border vertices. And this is where I am=20 > getting stuck. The problem is that the internal uvs should=20 > follow as good as possible, to minimize distortion issues. I=20 > ve been trying by using a mass-spring system on the mapping=20 > coordinates, and fixing the border verts so they cant move,=20 > but getting a good configuration to start the simulation is=20 > already a problem, coz you need to choose start positions for=20 > the internal vertices, spring rest lengths and so on. I tried=20 > several "project internal vertices on borders and=20 > interpolate" approaches, but for all of those its quite easy=20 > to find a case where it breaks down. >=20 > Here you see an example of what I want to achieve: >=20 http://users.pandora.be/ir_fuel/face_mapping_problem.jpg Oh, and I tried asking the artist to use Nurbs, which would give me a = nice parametrization to define the mapping, but that doesn't seem to be = the solution he is looking for ;) ;) Joris ------------------------------------------------------- This SF.Net email is sponsored by: Oracle 10g Get certified on the hottest thing ever to hit the market... Oracle 10g. Take an Oracle 10g class now, and we'll give you the exam FREE. = http://ads.osdn.com/?ad_id=3D3149&alloc_id=3D8166&op=3Dclick _______________________________________________ GDAlgorithms-list mailing list GDA...@li... https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list Archives: http://sourceforge.net/mailarchive/forum.php?forum_id=3D6188 ------------------------------------------------------- This SF.Net email is sponsored by: Oracle 10g Get certified on the hottest thing ever to hit the market... Oracle 10g. Take an Oracle 10g class now, and we'll give you the exam FREE. = http://ads.osdn.com/?ad_id149&alloc_id=8166&op=3Dick _______________________________________________ GDAlgorithms-list mailing list GDA...@li... https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list Archives: http://sourceforge.net/mailarchive/forum.php?forum_ida88 ------------------------------------------------------- This SF.Net email sponsored by Black Hat Briefings & Training. Attend = Black Hat Briefings & Training, Las Vegas July 24-29 -=20 digital self defense, top technical experts, no vendor pitches,=20 unmatched networking opportunities. Visit www.blackhat.com = _______________________________________________ GDAlgorithms-list mailing list GDA...@li... https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list Archives: http://sourceforge.net/mailarchive/forum.php?forum_ida88 |
