LSCM implementation by OpenNL shows overlapping triangles in its UV mapping

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I am using the Least square conformal map algorithm implemented by opennl without any change. With the spectral mode of the algorithm I get overlapping triangles in the UV mapping. For a cone triangulated object, it shows the following output,

enter image description here

Where the output should be something like this,

enter image description here

I went through the code and paper. Frankly I didn't understand the math behind the implementation and for that I could not find why this is happening. The cone object is here

# This file uses centimeters as units for non-parametric coordinates.

mtllib cone_triangulated.mtl
g default
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vn 0.723607 0.447214 0.525731
vn 0.850651 0.447214 0.276393
vn 0.894427 0.447214 0.000001
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g pasted__pCone1 group1
usemtl initialShadingGroup
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g default
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v 3.901170 -1.000000 -0.809017
v 3.679938 -1.000000 -0.587785
v 3.537898 -1.000000 -0.309017
v 3.488955 -1.000000 0.000000
v 3.537898 -1.000000 0.309017
v 3.679938 -1.000000 0.587785
v 3.901170 -1.000000 0.809017
v 4.179938 -1.000000 0.951057
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v 5.076741 -1.000000 0.809017
v 5.297972 -1.000000 0.587785
v 5.440012 -1.000000 0.309017
v 5.488955 -1.000000 0.000000
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vn -0.276393 0.447214 0.850651
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vn 0.276393 0.447214 0.850651
vn 0.525731 0.447214 0.723607
vn 0.723607 0.447214 0.525731
vn 0.850651 0.447214 0.276393
vn 0.894427 0.447214 0.000001
s 1
g pasted__pCone1 group1
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f 41/66/43 40/67/45 23/84/44
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f 39/68/46 38/69/47 23/84/44
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f 37/70/48 36/71/49 23/84/44
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s 2
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f 39/55/80 40/54/81 42/51/64
f 40/54/81 41/53/82 42/51/64
f 41/53/82 22/49/62 42/51/64

and the output object is here

v 5.44001 -1 -0.309017
v 5.29797 -1 -0.587786
v 5.07674 -1 -0.809017
v 4.79797 -1 -0.951057
v 4.48895 -1 -1
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v 3.67994 -1 0.587785
v 3.90117 -1 0.809017
v 4.17994 -1 0.951057
v 4.48895 -1 1
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v 5.07674 -1 0.809017
v 5.29797 -1 0.587785
v 5.44001 -1 0.309017
v 5.48895 -1 0
v 4.48895 1 0
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v 5.29797 -1 -0.587786
v 5.07674 -1 -0.809017
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v 4.48895 1 0
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f 41/41 22/22 42/42 
1

There are 1 answers

0
Andrey On

It seems that the implementation of this algorithm without segmentation and packing, it's only LSCM solver. Try InstantUV SDK instead or implement the algorithm yourself. more about LSCM here: https://members.loria.fr/Bruno.Levy/papers/LSCM_SIGGRAPH_2002.pdf