draw_pose.py

import cv2
import math
import numpy as np
from PIL import Image


def intrinsic_matrix_from_field_of_view(imshape, fov_degrees:float =55 ):   # nlf default fov_degrees 55
    imshape = np.array(imshape)
    fov_radians = fov_degrees * np.array(np.pi / 180)
    larger_side = np.max(imshape)
    focal_length = larger_side / (np.tan(fov_radians / 2) * 2)
    # intrinsic_matrix 3*3
    return np.array([   
        [focal_length, 0, imshape[1] / 2],
        [0, focal_length, imshape[0] / 2],
        [0, 0, 1],
    ])


def p3d_to_p2d(point_3d, height, width):    # point3d n*1024*3
    camera_matrix = intrinsic_matrix_from_field_of_view((height,width))
    camera_matrix = np.expand_dims(camera_matrix, axis=0)
    camera_matrix = np.expand_dims(camera_matrix, axis=0)    # 1*1*3*3
    point_3d = np.expand_dims(point_3d,axis=-1)     # n*1024*3*1
    point_2d = (camera_matrix@point_3d).squeeze(-1)
    point_2d[:,:,:2] = point_2d[:,:,:2]/point_2d[:,:,2:3]
    return point_2d[:,:,:]      # n*1024*2


def get_pose_images(smpl_data, offset):
    pose_images = []
    for data in smpl_data:   
        if isinstance(data, np.ndarray):
            joints3d = data
        else:
            joints3d = data.numpy()
        canvas = np.zeros(shape=(offset[0], offset[1], 3), dtype=np.uint8)
        joints3d = p3d_to_p2d(joints3d, offset[0], offset[1])
        canvas = draw_3d_points(canvas, joints3d[0], stickwidth=int(offset[1]/350))
        pose_images.append(Image.fromarray(canvas))
    return pose_images


def draw_3d_points(canvas, points, stickwidth=2, r=2, draw_line=True):
    colors = [
        [255, 0, 0],    # 0
        [0, 255, 0],    # 1
        [0, 0, 255],    # 2
        [255, 0, 255],  # 3
        [255, 255, 0],  # 4
        [85, 255, 0],   # 5
        [0, 75, 255],   # 6
        [0, 255, 85],   # 7
        [0, 255, 170],  # 8
        [170, 0, 255],  # 9
        [85, 0, 255],   # 10
        [0, 85, 255],   # 11
        [0, 255, 255],  # 12
        [85, 0, 255],   # 13
        [170, 0, 255],  # 14
        [255, 0, 255],  # 15
        [255, 0, 170],  # 16
        [255, 0, 85],   # 17
    ]
    connetions = [
        [15,12],[12, 16],[16, 18],[18, 20],[20, 22],
        [12,17],[17,19],[19,21],
        [21,23],[12,9],[9,6],
        [6,3],[3,0],[0,1],
        [1,4],[4,7],[7,10],[0,2],[2,5],[5,8],[8,11]
    ]
    connection_colors = [
        [255, 0, 0],    # 0
        [0, 255, 0],    # 1
        [0, 0, 255],    # 2
        [255, 255, 0],  # 3
        [255, 0, 255],  # 4
        [0, 255, 0],    # 5
        [0, 85, 255],   # 6
        [255, 175, 0],  # 7
        [0, 0, 255],    # 8
        [255, 85, 0],   # 9
        [0, 255, 85],   # 10
        [255, 0, 255],  # 11
        [255, 0, 0],    # 12
        [0, 175, 255],  # 13
        [255, 255, 0],  # 14
        [0, 0, 255],    # 15
        [0, 255, 0],    # 16
    ]

    # draw point
    for i in range(len(points)):
        x,y = points[i][0:2]
        x,y = int(x),int(y)
        if i==13 or i == 14:
            continue
        cv2.circle(canvas, (x, y), r, colors[i%17], thickness=-1)

    # draw line
    if draw_line:
        for i in range(len(connetions)):
            point1_idx,point2_idx = connetions[i][0:2]
            point1 = points[point1_idx]
            point2 = points[point2_idx]
            Y = [point2[0],point1[0]]
            X = [point2[1],point1[1]]
            mX = int(np.mean(X))
            mY = int(np.mean(Y))
            length = ((X[0] - X[1]) ** 2 + (Y[0] - Y[1]) ** 2) ** 0.5
            angle = math.degrees(math.atan2(X[0] - X[1], Y[0] - Y[1]))
            polygon = cv2.ellipse2Poly((mY, mX), (int(length / 2), stickwidth), int(angle), 0, 360, 1)
            cv2.fillConvexPoly(canvas, polygon, connection_colors[i%17])

    return canvas