OpenCap to C3D Converter

Easily and Reliably Convert
OpenCap Data to C3D

Convert OpenCap motion data to the industry-standard C3D format via OpenSim. This tool strongly supports data utilization in research and clinical settings.

Download App (Windows)

Total Downloads: ...

About the App

This application is designed to convert markerless motion capture data acquired by "OpenCap" (typically using smartphones) into the highly versatile C3D format. It utilizes intermediate data from OpenSim to achieve smooth and accurate conversion.

How to Use & Manual

📄 Open Official Manual (Google Docs)

1. Installation (First Time Only)

1

System Preparation

Please install the following three tools to run the software:

  • Microsoft Visual C++ Build Tools 2022
    Check "Desktop development with C++".
  • Anaconda
    Base for the Python environment. Default settings.
  • OpenSim 4.5
    Install with default settings after free registration.
2

Setup Python Env

Open "Anaconda Prompt" and run the following commands sequentially:

conda create -n opencap-processing python=3.11 -y conda activate opencap-processing conda install -c opensim-org opensim=4.5 -y pip install numpy pandas scipy ezc3d requests
3

App Installation

Run the distributed installer (OpenCap_Analyzer_Setup.exe).
After installation, manually copy your OpenCap session data (Data_xxx folders) directly into C:\opencap_analysis.

2. Operation Steps

A

Run Simulation (Tab 1)

Launch the app from the desktop icon (do not close the initial black console window).

Enter "Motion", "Height", "Weight", select the trial, and click "Run Musculoskeletal Simulation".
※ Warning: Takes approx. 3 hours per 1 second of data.

B

Export Results (Tab 2)

Choose extraction mode (Auto/Manual) and reference foot.

Specify the path to the base VICON template C3D file, and click "Generate Excel & C3D".

C

Output Files

The following files are saved in the Dynamics folder:

  • 📄 Excel Report: Detailed normalized analysis sheets.
  • 🏃 Fake C3D: C3D with ANALOG signals built-in.
  • 🧍 Marker-only C3D: C3D without kinetic data.

Developer Info

Keisuke Kon

Professor, Department of Prosthetics & Orthotics, Faculty of Health Sciences, Hokkaido University of Science

With expertise in clinical gait analysis, biomechanics, and prosthetics and orthotics, my research focuses on developing tools to apply motion capture data in clinical practice. For inquiries regarding this application, please contact via the researcher directory on the university website.