Mesh Comparison - Day 4

DSME-(Histogram-based) Qualitative Mesh Comparison in between ship CAD systems.

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Goal : Develop the module for 3D mesh comparison, in ACIS environment

Todo :

1. Study

• Qualitative shape (search, detection, matching, comparison, ...)
• MeshLab(VCG) or OpenMesh library
• ACIS & HOOPS

    2. Implementation

• Meshing(Solid, B-rep to facet data)
• Sampling on mesh surface
• Shape Distributions

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Sampling on mesh surface

• Be aware, that weighted random number generation based on the binary search, can cause the memory problem.
• In our case, sampling from the model has 15,725 faces are crashed when we pick a random face with binary search.
• So instead of the binary search, we use C++ random library, which has weighted random number generation.(LINK)
• Interval = [1,number of faces], and weight is the area for each face.

Shape Distributions

• "Shape Distributions"
• From sampled points, pick N pair of points and calculate D2 distance(Euclidean).
• The distance values are stored in B number of bins, and the number of distance is calculated.
• Interval of each bin = (max_distance-min_distance)/B

(※The 3D model only works when you see this post separately with Day-3+, by clicking the title of this post)

You can see the difference of first and second model.
First model is more simplified one.

And follow is the corresponding histogram of these two.

Overall shape is similar but there's differences, the metric distance of these two histogram will be implemented later.

For instance, another completely different model and corresponding histogram shows different shape of histogram.