Mesh2Marker

GUI tool (Blender add-on) that displays an MHR parametric body mesh and an OpenSim musculoskeletal model in the same 3D scene, lets the user map mesh vertices to anatomical markers on OpenSim segments, and exports a reusable correspondence file.

Mesh2Marker is an annex open-source project of the Mesh2Sim markerless- biomechanics pipeline. The link to the pipeline is the correspondence file, not code.

Why this tool

MHR topology is fixed: a given vertex index is the same anatomical point across all subjects, regardless of morphology. The mapping is defined once on a template mesh and reused for every subject. Mesh2Marker therefore produces a reusable, shareable asset (the equivalent of a standard marker set in optical mocap), not a per-subject output.

Repository layout: two artifacts, two channels, two licenses

This repository ships two distinct artifacts.

core/ — the business logic (PyPI, MIT)

Pure Python, no bpy. Parsing of .osim, Procrustes alignment, local-offset computation, correspondence-file schema and IO, validation against the shared vocabulary. Fully testable with plain pytest.

• Channel: published to PyPI — pip install mesh2marker.
• License: MIT.
• Audience: developers and the Mesh2Sim pipeline.

blender_addon/ — the Blender extension (Blender platform, GPL-3.0-or-later)

The thin bpy layer: UI, vertex picking, scene display, panels. It calls core/; no business logic lives here.

• Channel: distributed as a Blender extension (4.2+), via "Install from Disk" .zip or the Blender Extensions Platform. Never via pip for end users.
• License: GPL-3.0-or-later (any code importing bpy is a derivative work of Blender). An MIT core consumed by the GPL add-on is fine; the dependency direction is core → add-on, never the reverse.

Status

Early scaffolding. Business logic (.osim parsing, Procrustes alignment, correspondence-file schema) is not implemented yet.

Development

# Core: WSL / Linux, plain pytest
cd core
pytest

The Blender add-on is built with blender --command extension build.