The exported bvh fingers maintain a single pose without any changes

[bboyalong01]

Hello, I tried the bvh generated under three different skeletal modes, and all the fingers had bones. However, when I imported it into Blender, the fingers didn't show any motion changes. Is it because the finger poses in this project are supposed to remain unchanged?

[AmmarkoV]

Hi @bboyalong01, thanks for the report and a follow-up question first: could you share a short video sample of the input clip (or even a few representative frames)?
Whether the hands are clearly visible, well-lit, and reasonably large in frame makes a big difference here, and it would help me reproduce exactly what you're seeing.

Some technical background on how this project handles the hands, which should explain the behavior:

The fingers are not hard-coded to a fixed pose. MHR predicts a full per-frame hand/finger pose, and the BVH writer decodes it through body_model.lbs into per-joint finger
rotations. So in principle the fingers do animate.

However, two post-processing passes are ON by default in scripts/video.sh / scripts/offline_video.sh:

--sticky-hand-pose limits-gated inheritance. For each finger joint it accepts the newly predicted angle only if it falls inside an anatomical range-of-motion table;
otherwise it copies the previous frame's value.
--enforce-hand-limits clamps finger joint angles to that same anatomical table.

These were added for footage where the hands are not clearly visible (small, blurry, occluded, or out of frame). In that case MHR tends to hallucinate wild finger splay,
and without these guards the exported fingers look broken/jittery.

The side effect is exactly the symptom you describe: if the hands in your clip aren't well tracked, almost every predicted finger pose lands outside the limits, so sticky
mode keeps inheriting the first frame the fingers appear frozen in a single pose in Blender.

What to try:

1. Get the raw predicted fingers run with both guards off:
   --no-sticky-hand-pose --no-enforce-hand-limits
2. The fingers will then follow MHR's raw prediction. If your hands are clearly visible, this should give you real finger motion. If they're not, expect splay/jitter that's the trade-off the defaults exist to hide.
3. --zero-hand-pose forces neutral (straight) fingers, if you'd rather have a clean static pose than a noisy one.
4. Note --bvh-raw-fingers affects finger bone lengths / End-Site offsets, not motion it won't change whether they animate.

If you can share the sample, I can tell you whether disabling the guards will recover real motion for your specific clip, or whether the hands are simply too
small/occluded for reliable finger tracking.

[bboyalong01]

https://github.com/user-attachments/assets/78c04486-255e-46c3-92e1-7771ca17e13e
Hello，This is a video file, and the command to run it is
.\build\Release\fast_sam_3dbody_run.exe --from input16.mp4 --onnx-dir onnx --yolo onnx\yolo.onnx --gguf onnx\pipeline.gguf --bvh output\output16.bvh --bvh-template mixamo.bvh --no-enforce-hand-limits --no-sticky-hand-pose
The fingers are moving, but very slightly, and it feels like the finger movements are somewhat distorted

output16_0.zip

[AmmarkoV]

Hello,

You are right I tried the file
scripts/video.sh --from hands.mp4 --no-enforce-hand-limits --no-sticky-hand-pose
and because the hands are on the side they don't get picked up by the model.
I tried also the MocapNET and Mediapipe networks also without success.

The input video is simply to difficult for the SAM3DBody network! Its hand tracking is not so good to track this video!