Exports

Export utilities for common formats.

Export utilities for converting internal motion representations into common file formats.

This module is intended to hold lightweight serialization / export helpers that can be reused outside of interactive demos.

kimodo.exports.bvh.motion_to_bvh(local_rot_mats, root_positions, *, skeleton, fps)

Convert local rotations and root positions to BVH format; return UTF-8 string.

Parameters:

• local_rot_mats – (T, J, 3, 3) or (1, T, J, 3, 3) local rotation matrices.

• root_positions – (T, 3) or (1, T, 3) root joint positions (e.g. from posed joints).

• skeleton – Skeleton with bone_order_names, bvh_neutral_joints, etc.

• fps – Frames per second for the motion.

Notes

BVH is plain-text. Root is named “Root” with ZYX rotation order; leaf joints have no End Site block.

kimodo.exports.bvh.motion_to_bvh_bytes(local_rot_mats, root_positions, *, skeleton, fps)

Convert local rotations and root positions to BVH bytes (UTF-8).

Convenience wrapper around motion_to_bvh().

kimodo.exports.bvh.save_motion_bvh(

path,

local_rot_mats,

root_positions,

*,

skeleton,

fps,

)

Write local rotations and root positions to a BVH file at the given path.

Convert kimodo motion (y-up, z-forward) to MuJoCo qpos (z-up, x-forward) for G1 skeleton.

class kimodo.exports.mujoco.MujocoQposConverter(

input_skeleton,

xml_path='/home/drempe/projects/motion_foundation_model/kimodo-oss-release/mfm-oss/kimodo/assets/skeletons/g1skel34/xml/g1.xml',

)

Bases: object

Fast batch converter from our dictionary format to mujoco qpos with precomputed transforms.

In mujoco, the coordination is z up and x forward, right handed.

Features (30 joints): - root (pelvis, 7 = translation + rotation) + 29 dof joints (29)

In kimodo, the coordinate system is y up and z forward, right handed. Features (34 joints): - root (pelvis) + (34 - 1) joints; among these joints, 4 are end-effector joints added by kimodo.

Cached by (input_skeleton id, xml_path); repeated calls with the same args return the same instance.

__init__(

input_skeleton,

xml_path='/home/drempe/projects/motion_foundation_model/kimodo-oss-release/mfm-oss/kimodo/assets/skeletons/g1skel34/xml/g1.xml',

)

Initialize converter with precomputed transforms.

Parameters:

xml_path – Path to the mujoco XML file containing joint definitions

dict_to_qpos(

output,

device=None,

root_quat_w_first=True,

numpy=True,

mujoco_rest_zero=False,

)

Convert kimodo output dict to mujoco qpos format.

Parameters:

• output – dict with keys “local_rot_mats” and “root_positions”.

• device – device to use for the output.

• root_quat_w_first – If True, quaternion in qpos is (w,x,y,z).

• numpy – If True, convert the output to numpy array.

• mujoco_rest_zero – If True, joint angles are written so that kimodo rest (t-pose) maps to q=0 in MuJoCo. If False, write raw joint_dofs.

Returns:

(B, T, 7+J) mujoco qpos format.

Return type:

qpos

save_csv(qpos, csv_path)

project_to_real_robot_rotations(

local_rot_mats,

root_positions,

clamp_to_limits=True,

mujoco_rest_zero=False,

)

Project full 3D local rotations to G1 real robot DoF and back to 3D for viz.

Joint angles are extracted along each hinge axis, optionally clamped to XML limits, then reconstructed to 3D rotations. When mujoco_rest_zero=False (default), raw angles are used (baked-with-quat). When True, angles are relative to rest (0 = T-pose in MuJoCo).

to_qpos(

local_rot_mats,

root_positions,

root_quat_w_first=True,

mujoco_rest_zero=False,

)

Fast batch conversion from kimodo features to mujoco qpos format.

Parameters:

• local_rot_mats – (B, T, J, 3, 3) local rotation matrices (kimodo convention).

• root_positions – (B, T, 3) root positions.

• root_quat_w_first – If True, quaternion in qpos is (w,x,y,z).

• mujoco_rest_zero – If True, joint angles are written so that kimodo rest (t-pose) maps to q=0 in MuJoCo. If False, write raw joint_dofs.

Returns:

• root_trans (3) + root_quat (4) + joint_dofs (29) = 36 columns

Return type:

torch.Tensor of shape [batch, numFrames, 36] containing mujoco qpos data

kimodo.exports.mujoco.apply_g1_real_robot_projection(

skeleton,

joints_pos,

joints_rot,

clamp_to_limits=True,

)

Project G1 motion to real robot DoF (1-DoF per joint) with optional axis limits.

Extracts a single angle per hinge along its axis (1-DoF), optionally clamps to joint limits from the MuJoCo XML (when clamp_to_limits=True), then reconstructs 3D rotations and runs FK. T-pose (identity local rotations) is preserved.

Parameters:

• skeleton – G1 skeleton instance.

• joints_pos – (T, J, 3) or (B, T, J, 3) joint positions in global space.

• joints_rot – (T, J, 3, 3) or (B, T, J, 3, 3) global rotation matrices.

• clamp_to_limits – If True, clamp joint angles to XML axis limits (default True).

Returns:

(posed_joints, global_rot_mats) as tensors, same shape as inputs (batch preserved).

Convert kimodo motion to AMASS/SMPL-X compatible parameters (axis-angle, Y-up or Z-up).

kimodo.exports.smplx.get_amass_parameters(

local_rot_mats,

root_positions,

skeleton,

z_up=True,

)

Convert local rot mats and root positions to AMASS-style trans and pose_body; optional z_up coordinate transform.

Our method generates motions with Y-up and +Z forward; if z_up=True, transform to Z-up and +Y forward as in AMASS.

class kimodo.exports.smplx.AMASSConverter(

fps,

skeleton,

beta_path='/home/drempe/projects/motion_foundation_model/kimodo-oss-release/mfm-oss/kimodo/assets/skeletons/smplx22/beta.npy',

mean_hands_path='/home/drempe/projects/motion_foundation_model/kimodo-oss-release/mfm-oss/kimodo/assets/skeletons/smplx22/mean_hands.npy',

)

Bases: object

__init__(

fps,

skeleton,

beta_path='/home/drempe/projects/motion_foundation_model/kimodo-oss-release/mfm-oss/kimodo/assets/skeletons/smplx22/beta.npy',

mean_hands_path='/home/drempe/projects/motion_foundation_model/kimodo-oss-release/mfm-oss/kimodo/assets/skeletons/smplx22/mean_hands.npy',

)

convert_save_npz(output, npz_path, z_up=True)

save_npz(

trans,

root_orient,

pose_body,

base_output,

npz_path,

)