SAM 3D Body: Export FBX

When ComfyUI-SAM3DBody first shipped, one of the first questions in the comments was whether it did rigging like Meta's own demo site - a skeleton you can actually pose and animate, not just a static mesh. SAM3DBodyExportFBX is that answer. Where SAM3DBodyExportMesh writes raw geometry, this node writes an FBX with the skeleton baked in, ready to drop into Blender, Unreal, Unity, or wherever you're doing character work. The default filename literally says sam3d_rigged.fbx - that's the point of the node in one word.

How it works

Per the pack's own credits, the rigging logic here is adapted from ComfyUI-UniRig's Blender installation code, meaning this step is doing real work beyond a format conversion - it's building an actual bone hierarchy from the reconstructed mesh and pose, not just wrapping the geometry in a different file container. That's also why it's heavier and slower than the plain STL export: there's a rig-building pass happening that the mesh-only export skips entirely.

The inputs and outputs that matter

• mesh_data (SAM3D_OUTPUT) - required, from SAM3DBodyProcess, SAM3DBodyProcessAdvanced, or SAM3DBodyAddMeshToSkeleton.
• output_filename (default sam3d_rigged.fbx) - where the file gets written.

One output: fbx_path (STRING) - the path to the exported FBX. Wire this straight into SAM3DBodyPreviewRiggedMesh if you want to check the rig inside ComfyUI before opening a full 3D application.

How to install it

Via ComfyUI Manager: search SAM3DBody, install, restart. Manual:

cd ComfyUI/custom_nodes
git clone https://github.com/PozzettiAndrea/ComfyUI-SAM3DBody.git
cd ComfyUI-SAM3DBody
pip install -r requirements.txt --upgrade
python install.py

This node's rigging pipeline leans on Blender-derived code under the hood, so it's a genuinely heavier dependency than the rest of the pack's export nodes - if the manual install path errors specifically around this step, re-check that pip install -r requirements.txt --upgrade actually completed cleanly rather than partially.

Common issues & troubleshooting

Bones come into Blender disconnected, floating on their own instead of a proper linked skeleton. This is a real, reported issue on the pack's release thread, not something you're doing wrong on your end. If you hit it, it's worth checking the pack's GitHub issues before spending hours manually reparenting bones - there's a decent chance it's a known, tracked bug rather than a one-off.

The mesh comes out mirrored left-right. Also a reported issue, independent of the disconnected-bones one. Worth a visual check against the source photo before you build an animation pipeline on top of an export that's flipped.

Rig geometry doesn't match what you saw in debug_image. Run SAM3DBodyVisualize on the same mesh_data right before exporting to confirm the mesh itself looks right - if it does and the FBX still looks wrong once loaded elsewhere, the issue is in the rigging step specifically, which narrows down where to look.

Export takes noticeably longer than SAM3DBodyExportMesh. Expected - the rig-building pass is real computation, not a format formality. If you don't actually need bones (say, you're just archiving geometry or 3D printing), the plain mesh export is faster and simpler.