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Khaled Mamou's Blog
Thursday, 2 June 2016
Sunday, 24 January 2016
Latest VHACD source code
The latest version of the VHACD code is available here https://github.com/kmammou/vhacd
Friday, 26 June 2015
A Simple C++ Class for 3D Mesh Decimation
Some time ago I wrote a simple C++ class to simplify a 3D mesh. It is based on Michael Garland's article "Surface Simplification Using Quadric Error Metrics"
The code is available under a BSD license.
A win64 executable is also available for quick testing.
The code produces good quality results. However, it is relatively slow!
Usage:
MeshSimplification fileNameIn.obj targetNTrianglesDecimatedMesh targetNVerticesDecimatedMesh maxDecimationError fileNameOut.obj
For instance, to generate a decimated mesh with 1000 triangles use the following command line:
MeshSimplification input.obj 1000 0 1.0 decimated.obj
To generate a decimated mesh with 1000 vertices:
MeshSimplification input.obj 0 1000 1.0 decimated.obj
MeshSimplification input.obj 0 0 0.01 decimated.obj
To use the mesh decimation class in your code, proceed as follows:
// input mesh Vec3<Float> * points; Vec3<int> * triangles; // Fill points and triangles with input mesh // ... // decimate mesh MeshDecimator myMDecimator; myMDecimator.Initialize(nPoints, nTriangles, points, triangles); myMDecimator.Decimate(targetNVerticesDecimatedMesh, targetNTrianglesDecimatedMesh, maxDecimationError); // allocate memory for decimated mesh size_t nVerticesDecimatedMesh = myMDecimator.GetNVertices(); size_t nTrianglesDecimatedMesh = myMDecimator.GetNVertices(); Vec3<Float> * decimatedMeshPoints = new Vec3<Float>[nVerticesDecimatedMesh]; Vec3<int> * decimatedMeshTriangles = new Vec3<int>[nTrianglesDecimatedMesh]; // retrieve decimated mesh myMDecimator.GetMeshData(decimatedMeshPoints, decimatedMeshTriangles);
Friday, 10 April 2015
Thursday, 2 April 2015
Wednesday, 21 January 2015
OpenCL Acceleration for VHACD
Since I don’t expect to have time in the near future to work on VHACD , I am writing this post to keep track of the performance
improvements obtained after the latest optimizations I added. The source code is available here.
Experimental Evaluation
Table 1 compares the computation times (cf. Section "Machine description") of VHACD 2.0 and VHACD 2.2 obtained by using the configuration described below (cf. Table 2). These results show that VHACD 2.2 is an order of magnitude faster than VHACD 2.0. The gains are mainly obtained thanks to the convexhull approximation (cf. Section "Updates"). The OpenCL acceleration provides 3050% lower computation times when compared to the CPUonly version of VHACD 2.2.
Experimental Evaluation
Table 1 compares the computation times (cf. Section "Machine description") of VHACD 2.0 and VHACD 2.2 obtained by using the configuration described below (cf. Table 2). These results show that VHACD 2.2 is an order of magnitude faster than VHACD 2.0. The gains are mainly obtained thanks to the convexhull approximation (cf. Section "Updates"). The OpenCL acceleration provides 3050% lower computation times when compared to the CPUonly version of VHACD 2.2.
The code is still not fully optimized and more
improvements could be expected!
VHACD 2.0 (CPU only)

VHACD 2.2 (CPU+GPU)


army_man

650s

65s

block

220s

26s

Bunny

317s

30s

Camel

388s

34s

Casting

744s

79s

Chair

408s

42s

Cow1

314s

30s

Cow2

349s

32s

deer_bound

411s

34s

Parameter

Config.
1

resolution

8000000

max. depth

20

max. concavity

0.001

plane downsampling

4

convexhull downsampling

4

alpha

0.05

beta

0.05

gamma

0.0005

delta

0.05

pca

0

mode

0

max. vertices per convexhull

64

min. volume to add vertices to convexhulls

0.0001

convexhull approximation

1

Updates
VHACD 2.2 include the following updates:
 OpenCL acceleration to compute the clipped volumes on the GPU
 Convexhull approximation to accelerate concavity calculations
 Added local concavity measure to clipping cost calculation
 Changed command line parameters
To do
When I'll find time (probably not soon), I need to do the following:
When I'll find time (probably not soon), I need to do the following:
 Test the code and build executables for different platforms (i.e., Linux, Mac OS), and
 Update the Blender addon to make it work with the new command line parameters.
Machine description
 OS: Windows 8.1 Pro 64bit
 CPU: Intel(R) Core(TM) i72600 CPU @ 3.40GHz (8 CPUs), ~3.4GHz
 GPU: NVIDIA GeForce GTX 550 Ti
 Memory: 10240MB RAM
Thursday, 18 December 2014
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