CMU Motion Capture Database Viewer ver. 1.0

Today I opened CMU Motion Capture Database Viewer webpage. You can connect by clicking the tab located above from this blog or the direct link below.

CMU Motion Capture Database Viewer

You can select a subject and corresponding data by selection list, then the animation will be visualized in X3DOM canvas immediately. 

If you have any feedback, please let me know.

asf/amc to X3D H-Anim conversion

Recently, we're working on human gait analysis-related research. While studying related literature, we found CMU Graphics Lab Motion Capture Database, which has huge amount of motion capture data using Vicon motion capture system. Database includes video taken while capturing motion (mpg), sensor raw data (c3d) ,reconstructed skeleton from sensor data (asf/amc) and animated video of skeleton (avi). There are tvd files you can download but I couldn't get much information about the file format.

The motivation of this work is that it is difficult to find the motion capture data that I wanted. For instance, I wanted to find the data of walking along the circular path over a minute. All you can do is search the database with keyword "walking" and should download each mpg or avi video and check it is longer than a minute and if a person walked along a circular path. It is very exhaustive work and I found it is faster to download entire avi clips in database and see the videos one by one (because downloading each avi in searched result takes too much time).

So my idea is to make a webpage using X3DOM, shows skeleton animation in interactive 3D without manually download files. It is possible because H-Anim specification is ready for the standardized character animation description and thankfully, X3DOM developers implemented the specification.

Therefore I implemented a converter from asf/amc to X3D H-Anim. The converted x3d file can be visualized in X3DOM framework. To reduce the work needed I use the exist MATLAB parser for asf/amc. If you are Korean, this page helps you to understand how asf/amc format describes skeleton data.

The important and difficult part of converting asf/amc to H-Anim specification is the existence of "axis" information in asf file format, and inverted multiplication order or rotation matrix between those two. In asf, local axis of a idle(neutral?) bone may not aligned with global coordinate. However in H-Anim, bone (joint in H-Anim specification) is aligned with global coordinate. So you have to convert animation data stored in amc by changing local rotation to global rotation. And asf/amc descripbes left-to-right multiplication of rotation matrix, while rotation matrix of H-Anim should be right-to-left.

Below is an example of X3DOM scene, converted from asf/amc. (I think Google Blogger now blocks external js include...?)

Link


Now I'm converting the entire database (which takes so much time because MATLAB is not good for this kind of work...) and I planned to make a separate page to visualize CMU database using X3DOM. I hope to finish and open it in near future.

Mesh Comparison - Javascript & ASP.NET service

Web page for mesh comparison

Pure JS, client-side scripting

• For the interactive servicing of mesh comparison(or retrieval), I made the web page for it using X3DOM for visualization and JS for calculation.
• It was pretty successful, and you can see the result in the below link.
• You can test with your OBJ or OFF mesh data or,
• You can download sample model from here.
• http://ssong.kaist.ac.kr/upload_test.html
• (OBJ and OFF parser may have some limitation.)

Using ASP.NET

• Soon, I realize that the client-side scripting is not enough for maintaining DB for mesh data, and shape descriptors.
• I'm not familiar with the various web technologies and choose a server-side programming method that I can develop fast-ASP.NET
• First step is develop the calculation module with C# DLL, which is just a conversion task from JS.
• Second step is designing the layout, which I'm not good at, and connecting the module with elements in the page.
• Also, one functionality added is storing the uploaded mesh data into server machine for later development.
• For dynamic visualization of X3DOM, "HTMLGenericControl" of ASP.NET was used to change the attribute value in X3D node.(Is there any performance issue?)
• You can test with your OBJ of OFF mesh data, but you should keep in mind that the DATA YOU UPLOADED WILL BE STORED IN MY SERVER MACHINE.
• (OBJ and OFF parser may have some limitation.)
• http://143.248.54.5:1234/default.aspx

Further Issues

In development

• The postback harms the UX...

• Performance itself seems worse than JS

• Hopefully, I will solve the problems by modifying the structures.

• Model DB displaying, selection and retrieval.

In methodology

• I didn't clearly understand the Histogram --> PDF part yet.

• Several approaches on normalization, bin width selection and PDF comparing.

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.

Mesh_Comparison - Day 3+

HTML5 Interactive

You can see the results in previous post interactively, by X3DOM.
Wheel click + drag : panning
Left button click + drag : rotating
Right button click + drag : zooming