Convert FBX to C3D

Understanding FBX and C3D file formats

FBX (Filmbox) is a popular 3D file format developed by Autodesk, widely used for storing 3D models, animations, and scenes. It supports a variety of data including geometry, textures, lighting, and animation, making it a standard in the animation, game development, and visual effects industries.

C3D (Coordinate 3D) is a specialized file format primarily used in biomechanics and motion capture. It stores 3D motion data, force plate data, and analog signals, making it essential for researchers and professionals working with human movement analysis.

Why convert FBX to C3D?

Converting FBX to C3D is necessary when you need to use 3D animation or motion data from general-purpose 3D software in biomechanics or motion analysis applications. This conversion allows for the integration of animation data into motion capture workflows for further analysis or visualization.

How to convert FBX to C3D

Direct conversion from FBX to C3D is not commonly supported by most 3D software, as these formats serve different industries. However, you can achieve this conversion through a two-step process:

1. Export motion data from FBX: Use 3D animation software like Autodesk MotionBuilder or Blender to export the motion capture or animation data from your FBX file. Export the data in a format compatible with motion capture tools, such as BVH (Biovision Hierarchy).
2. Convert to C3D: Use specialized motion capture software such as MotionBuilder (with plugins), BTK (Biomechanical ToolKit), or Vicon Nexus to import the BVH file and then export it as a C3D file.

Recommended software for FBX to C3D conversion

• Autodesk MotionBuilder: Import your FBX file, retarget or clean up the animation, then export as BVH. Use a C3D conversion plugin or external tool to convert BVH to C3D.
• BTK (Biomechanical ToolKit): An open-source toolkit that can convert BVH files to C3D format. It is suitable for researchers and advanced users.
• Vicon Nexus: A professional motion capture software that supports importing BVH and exporting C3D files, ideal for biomechanics labs.

Step-by-step example using Autodesk MotionBuilder and BTK

1. Open your FBX file in Autodesk MotionBuilder.
2. Go to File → Export → BVH to export the animation as a BVH file.
3. Open BTK and use its conversion tools to import the BVH file and export it as a C3D file.

Conclusion

While there is no direct one-click solution for converting FBX to C3D, using a combination of 3D animation and motion capture software allows you to transfer animation data between these formats. Autodesk MotionBuilder and BTK are among the best tools for this workflow.