Description

Topological similarity estimation for 3D models (face-vertex meshes) using multiresolutional Reeb graphs (MRG).

The MRG method was proposed by Hilaga et al. in [1]. This implementation was used to obtain experimental results that were reported in [2] and [3].

Implementation Notes

• Programming language: Java
• Software Prerequisites: JavaSE 1.4+
  • the code was developed using JavaSE 1.4, so it does not use Java generics (introduced in JavaSE 5.0)
• 3D models must be specified in specially-formatted VRML files (see below)
  • Face-vertex meshes with triangle and quad faces are supported
  • 16 sample models are included in this package

Package Contents

Source Code

The source code is located in src/ directory. There are two main java classes:

1. ExtractReebGraph class constructs MRGs for 3D models and saves them into text files.

• This procedure for MRG construction is described in Section 4 of [1].
• Usage:
  java ExtractReebGraph <num_pts> <mu_coeff> <mrg_size> <model_1>.wrl <model_2>.wrl ... <model_N>.wrl
  where:
  • <num_pts> – target number of vertices prior to MRG construction (triangle faces are resampled to match <num_pts>)
  • <mu_coeff> – coefficient for calculating threshold parameter r=sqrt(mu_coeff * area(S)), which in turn is used to approximate values of function mu in [1]
  • <mrg_size> – number of ranges in the finest resolution of MRG (parameter K in [1])
  • <model_i>.wrl – i-th VRML model for i=[1,N] (MRG for each model is stored in <model_i>.mrg)

2. CompareReebGraph class implements matching algorithm for a pairwise comparison of MRGs.

• The matching algorithm is described in Section 5 of [1].
• Usage:
  java CompareReebGraph <num_pts> <mu_coeff> <mrg_size> <sim_weight> <model_1>.wrl ... <model_N>.wrl
  where:
  • <num_pts> – target number of vertices prior to MRG construction (triangle faces are resampled to match <num_pts>)
  • <mu_coeff> – coefficient for calculating threshold parameter r=sqrt(mu_coeff * area(S)), which in turn is used to approximate values of function mu in [1]
  • <mrg_size> – number of ranges in the finest resolution of MRG (parameter K in [1])
  • <sim_weight> – weight w used in similarity function (trade-off between attributes a and l in [1])
  • <model_i>.wrl – a list of VRML models to compare for i=[1,N] (it is assumed that each model was processed using ExtractReebGraph program, and MRG for <model_i>.wrl was stored in <model_i>.mrg)

CAD Models

The following 3D models in VRML format can be found in models/ directory:

VRML parser in ExtractReebGraph can only handle specially-formatted face-vertex meshes:

• Vertex lists are assumed to be enclosed by strings point [\n and ]\n
  • Coordinates for each point must appear on a separate line in the VRML file (e.g., 1.5 3.2 0.2,\n)
• Face lists are assumed to be enclosed by strings coordIndex [\n and ]\n
  • Each face must appear on a separate line (e.g., 0, 2, 1, -1,\n encodes a triangle face)

Sample Usage

Compiling

$ javac src/*.java

MRG Construction

3D models must be saved in a specially-formatted VRML files (see CAD Models)

$ ls -1 models/*.wrl  | head -5

models/bracket_1.wrl
models/bracket_2.wrl
models/bracket_3.wrl
models/fork_1.wrl
models/fork_2.wrl

Compute MRGs for all *.wrl files in a directory:

$ ls models/*.wrl  | xargs  java -cp "./src/" -Xmx1024m ExtractReebGraph   4000 0.0005 128

MRGs are saved into *.mrg files:

$ ls -1 models/*.mrg  | head -5

models/bracket_1.mrg
models/bracket_2.mrg
models/bracket_3.mrg
models/fork_1.mrg
models/fork_2.mrg

MRG Matching

Compute pairwise similarity values for 3D models using their MRG representation:

$ ls models/*.wrl  | xargs  java -cp "./src/" -Xmx1024m CompareReebGraph   4000 0.0005 128 0.5

The similarity values are stored in log_<pts_num>_<mu_coef>_<mrg_size>_<sim_weight> file:

$ shuf log_4000_5.0E-4_128_0.5 | head -5

Similarity between models/goodpart_2.wrl and models/fork_3.wrl is 0.7661396393161327
Similarity between models/housing_1.wrl and models/socket_2.wrl is 0.6789623740585898
Similarity between models/fork_3.wrl and models/bracket_2.wrl is 0.8125245864576977
Similarity between models/goodpart_1.wrl and models/socket_2.wrl is 0.8162694461373452
Similarity between models/bracket_3.wrl and models/housing_1.wrl is 0.6865232310951028

Retrieval Results

Pairwise similarity values can be used to rank 3D models in terms of their relevance to a query model. Five top-ranked models for selected queries are:

License

GNU General Public License

References

1. Masaki Hilaga, Yoshihisa Shinagawa, Taku Kohmura, and Tosiyasu L. Kunii.
   Topology Matching for Fully Automatic Similarity Estimation of 3D Shapes.
   SIGGRAPH, 2001. doi:10.1145/383259.383282

2. Dmitriy Bespalov, William C. Regli, and Ali Shokoufandeh.
   Reeb graph based shape retrieval for CAD.
   ASME IDETC, 2003. doi:10.1115/DETC2003/CIE-48194

3. Dmitriy Bespalov, Cheuk Yiu Ip, William C. Regli, and Joshua Shaffer.
   Benchmarking search techniques for CAD.
   ACM SPM, 2005. doi:10.1145/1060244.1060275