> For the complete documentation index, see [llms.txt](https://docs.theiamarkerless.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.theiamarkerless.com/apollo-v2024/theia3d-documentation/data-formats/c3d-files.md).

# C3D Files

Pose (.c3d) files can be saved and used to perform post-processing analysis steps in Visual3D software. Use the Save Skeleton Poses button to save skeleton pose .c3d files, or navigate to Save Skeleton Poses under the [File Menu](/apollo-v2024/theia3d-documentation/batch-processing/file-menu.md). Saved pose .c3d files can be opened in Visual3D, and a subject-specific model will automatically be applied to the Theia3D data in Visual3D without requiring the model to be defined.

The movement of each tracked individual is conveyed within the .c3d file using ROTATION signals, which are 4x4 pose (position and orientation) matrices for each segment’s local segment coordinate system, for every frame of data. A description of the [ROTATION data type](https://www.wiki.has-motion.com/doku.php?id=visual3d:documentation:c3d_signal_types:rotation_data_type) is available from Visual3D documentation. Raw tracked landmarks are not included as signals in any output files from Theia3D.


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