motion_utils.py

import torch
import numpy as np
import matplotlib.pyplot as plt
plt.rcParams['animation.ffmpeg_path'] = '/usr/bin/ffmpeg'
from mpl_toolkits.mplot3d import Axes3D
from matplotlib.animation import FuncAnimation, PillowWriter
from mpl_toolkits.mplot3d.art3d import Poly3DCollection
import mpl_toolkits.mplot3d.axes3d as p3

def qrot(q, v):
    """
    Rotate vector(s) v about the rotation described by quaternion(s) q.
    Expects a tensor of shape (*, 4) for q and a tensor of shape (*, 3) for v,
    where * denotes any number of dimensions.
    Returns a tensor of shape (*, 3).
    """
    assert q.shape[-1] == 4
    assert v.shape[-1] == 3
    assert q.shape[:-1] == v.shape[:-1]

    original_shape = list(v.shape)
    # print(q.shape)
    q = q.contiguous().view(-1, 4)
    v = v.contiguous().view(-1, 3)

    qvec = q[:, 1:]
    uv = torch.cross(qvec, v, dim=1)
    uuv = torch.cross(qvec, uv, dim=1)
    return (v + 2 * (q[:, :1] * uv + uuv)).view(original_shape)

def qinv(q):
    assert q.shape[-1] == 4, 'q must be a tensor of shape (*, 4)'
    mask = torch.ones_like(q)
    mask[..., 1:] = -mask[..., 1:]
    return q * mask

def recover_root_rot_pos(data):
    rot_vel = data[..., 0]
    r_rot_ang = torch.zeros_like(rot_vel).to(data.device)
    '''Get Y-axis rotation from rotation velocity'''
    r_rot_ang[..., 1:] = rot_vel[..., :-1]
    r_rot_ang = torch.cumsum(r_rot_ang, dim=-1)

    r_rot_quat = torch.zeros(data.shape[:-1] + (4,)).to(data.device)
    r_rot_quat[..., 0] = torch.cos(r_rot_ang)
    r_rot_quat[..., 2] = torch.sin(r_rot_ang)

    r_pos = torch.zeros(data.shape[:-1] + (3,)).to(data.device)
    r_pos[..., 1:, [0, 2]] = data[..., :-1, 1:3]
    '''Add Y-axis rotation to root position'''
    r_pos = qrot(qinv(r_rot_quat), r_pos)

    r_pos = torch.cumsum(r_pos, dim=-2)

    r_pos[..., 1] = data[..., 3]
    return r_rot_quat, r_pos

def recover_from_ric(data, joints_num):
    r_rot_quat, r_pos = recover_root_rot_pos(data)
    positions = data[..., 4:(joints_num - 1) * 3 + 4]
    positions = positions.view(positions.shape[:-1] + (-1, 3))

    '''Add Y-axis rotation to local joints'''
    positions = qrot(qinv(r_rot_quat[..., None, :]).expand(positions.shape[:-1] + (4,)), positions)

    '''Add root XZ to joints'''
    positions[..., 0] += r_pos[..., 0:1]
    positions[..., 2] += r_pos[..., 2:3]

    '''Concate root and joints'''
    positions = torch.cat([r_pos.unsqueeze(-2), positions], dim=-2)

    return positions

def plot_3d_motion(save_path, kinematic_tree, joints, title, figsize=(10, 10), fps=120, radius=4):
#     matplotlib.use('Agg')

    title_sp = title.split(' ')
    if len(title_sp) > 10:
        title = '\n'.join([' '.join(title_sp[:10]), ' '.join(title_sp[10:])])
    def init():
        # ax.set_xlim3d([-radius / 2, radius / 2])
        # ax.set_ylim3d([0, radius])
        # ax.set_zlim3d([0, radius])
        # # print(title)
        # fig.suptitle(title, fontsize=20)
        # ax.grid(b=False)

        nb_joints = joints.shape[1]
        limits = 1000 if nb_joints == 21 else 2
        ax.set_xlim(-limits, limits)
        ax.set_ylim(-limits, limits)
        ax.set_zlim(0, limits)
        fig.suptitle(title, fontsize=20)
        ax.grid(b=False)

    def plot_xzPlane(minx, maxx, miny, minz, maxz):
        ## Plot a plane XZ
        verts = [
            [minx, miny, minz],
            [minx, miny, maxz],
            [maxx, miny, maxz],
            [maxx, miny, minz]
        ]
        xz_plane = Poly3DCollection([verts])
        xz_plane.set_facecolor((0.5, 0.5, 0.5, 0.5))
        ax.add_collection3d(xz_plane)

    #         return ax

    # (seq_len, joints_num, 3)
    data = joints.copy().reshape(len(joints), -1, 3)
    fig = plt.figure(figsize=figsize)
    # ax = p3.Axes3D(fig)
    ax = fig.add_subplot(111, projection='3d')
    init()
    MINS = data.min(axis=0).min(axis=0)
    MAXS = data.max(axis=0).max(axis=0)
    colors = ['red', 'blue', 'black', 'red', 'blue',  
              'darkblue', 'darkblue', 'darkblue', 'darkblue', 'darkblue',
             'darkred', 'darkred','darkred','darkred','darkred']
    frame_number = data.shape[0]
    #     print(data.shape)

    height_offset = MINS[1]
    data[:, :, 1] -= height_offset
    trajec = data[:, 0, [0, 2]]
    
    data[..., 0] -= data[:, 0:1, 0]
    data[..., 2] -= data[:, 0:1, 2]

    #     print(trajec.shape)

    def update(index):
        #         print(index)
        # ax.lines = []
        # ax.collections = []
        for line in ax.lines:
            line.remove()
        for collection in ax.collections:
            collection.remove()
        ax.view_init(elev=120, azim=-90)
        ax.dist = 7.5
        #         ax =
        plot_xzPlane(MINS[0]-trajec[index, 0], MAXS[0]-trajec[index, 0], 0, MINS[2]-trajec[index, 1], MAXS[2]-trajec[index, 1])
#         ax.scatter(data[index, :22, 0], data[index, :22, 1], data[index, :22, 2], color='black', s=3)
        
        if index > 1:
            ax.plot3D(trajec[:index, 0]-trajec[index, 0], np.zeros_like(trajec[:index, 0]), trajec[:index, 1]-trajec[index, 1], linewidth=1.0,
                      color='blue')
        #             ax = plot_xzPlane(ax, MINS[0], MAXS[0], 0, MINS[2], MAXS[2])
        
        
        for i, (chain, color) in enumerate(zip(kinematic_tree, colors)):
#             print(color)
            if i < 5:
                linewidth = 4.0
            else:
                linewidth = 2.0
            ax.plot3D(data[index, chain, 0], data[index, chain, 1], data[index, chain, 2], linewidth=linewidth, color=color)
        #         print(trajec[:index, 0].shape)

        plt.axis('off')
        ax.set_xticklabels([])
        ax.set_yticklabels([])
        ax.set_zticklabels([])

    ani = FuncAnimation(fig, update, frames=frame_number, interval=1000/fps, repeat=False)

    ani.save(save_path, fps=fps)
    plt.close()