Mediapipe-姿态估计实例

Mediapipe简介

Mediapipe 是由 Google Research 开发的一款开源框架，旨在帮助开发者轻松地构建、测试和部署复杂的多模态、多任务的机器学习模型。它特别擅长于实时处理和分析音频、视频等多媒体数据。以下是 Mediapipe 的一些关键特点和组件：

关键特点

多平台支持：Mediapipe 支持在多个平台上运行，包括桌面、移动设备和网页。这使得开发者可以轻松地将模型部署到不同的平台上。
高效的实时处理：Mediapipe 具有高度优化的性能，能够在资源受限的设备上进行实时处理。这使其特别适合于移动设备和嵌入式系统。
模块化设计：Mediapipe 使用图表（graph）来组织和连接不同的处理模块。这种设计使得开发者可以灵活地组合和复用不同的处理组件。
丰富的预构建解决方案：Mediapipe 提供了许多预构建的解决方案，如人脸检测、手部追踪、姿态估计等，开发者可以直接使用这些解决方案来快速构建应用。

主要组件

图表（Graph）：Mediapipe 的核心是其图表结构，图表定义了数据流和处理模块的连接方式。每个图表由一系列节点（nodes）和边（edges）组成，节点表示具体的处理模块，边表示数据在节点之间的流动。
节点（Nodes）：节点是图表的基本单元，表示具体的处理操作。Mediapipe 提供了许多内置的节点，如数据输入输出节点、图像处理节点、机器学习推理节点等。
数据包（Packets）：数据包是图表中传输的数据单元，节点之间通过发送和接收数据包来通信。数据包可以包含各种类型的数据，如图像帧、音频信号、检测结果等。
计算机视觉解决方案：Mediapipe 提供了许多预构建的计算机视觉解决方案，这些解决方案已经高度优化，能够在实时应用中使用。常见的解决方案包括人脸检测、手部追踪、姿态估计、对象检测等。

常见使用场景

姿态估计（Pose Estimation）：Mediapipe 可以实时检测和追踪人体的关键点（如肩膀、肘部、膝盖等），并估计人体的姿态。这对于体育训练、动作捕捉、增强现实等应用非常有用。
手部追踪（Hand Tracking）：Mediapipe 能够检测和追踪手部的关键点，提供手势识别和手部动作分析的能力。这在手势控制、虚拟现实、手写输入等应用中有广泛的应用。
人脸检测（Face Detection）：Mediapipe 提供了高效的人脸检测和关键点追踪功能，可以用于面部识别、表情分析、虚拟化妆等场景。
对象检测（Object Detection）：Mediapipe 还提供了实时的对象检测解决方案，可以用于监控、无人驾驶、智能家居等领域。

示例代码

以下是一个使用 Mediapipe 进行姿态估计的简单示例：

import cv2
import mediapipe as mp# Initialize mediapipe pose class.
mp_pose = mp.solutions.pose
pose = mp_pose.Pose()# Initialize mediapipe drawing class, useful for annotation.
mp_drawing = mp.solutions.drawing_utils# Load the video file or start webcam capture.
cap = cv2.VideoCapture(0)  # Use 0 for webcam, or provide video file pathwhile cap.isOpened():ret, frame = cap.read()if not ret:break# Convert the BGR image to RGB.image_rgb = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)# Process the image and detect the pose.result = pose.process(image_rgb)# Draw the pose annotation on the image.if result.pose_landmarks:mp_drawing.draw_landmarks(frame, result.pose_landmarks, mp_pose.POSE_CONNECTIONS)# Display the frame with pose landmarks.cv2.imshow('Pose Estimation', frame)# Break the loop if 'q' is pressed.if cv2.waitKey(10) & 0xFF == ord('q'):break# Release the video capture object and close display window.
cap.release()
cv2.destroyAllWindows()

这段代码使用 Mediapipe 的姿态估计功能，读取视频流并实时绘制人体的关键点。你可以使用摄像头实时捕捉人体姿态，也可以处理预录制的视频文件。

实例1-读取视频流并进行骨骼点绘制：

import cv2
import mediapipe as mp# Initialize mediapipe pose class.
mp_pose = mp.solutions.pose
pose = mp_pose.Pose()# Initialize mediapipe drawing class, useful for annotation.
mp_drawing = mp.solutions.drawing_utils# Load the video file.
cap = cv2.VideoCapture('D:/basketball.mp4')# Check if the video is opened successfully.
if not cap.isOpened():print("Error: Could not open video.")exit()while cap.isOpened():ret, frame = cap.read()if not ret:print("Reached the end of the video.")break# Convert the BGR image to RGB.image_rgb = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)# Process the image and detect the pose.result = pose.process(image_rgb)# Draw the pose annotation on the image.if result.pose_landmarks:mp_drawing.draw_landmarks(frame, result.pose_landmarks, mp_pose.POSE_CONNECTIONS)# Display the frame with pose landmarks.cv2.imshow('Pose Estimation', frame)# Break the loop if 'q' is pressed.if cv2.waitKey(10) & 0xFF == ord('q'):break# Release the video capture object and close display window.
cap.release()
cv2.destroyAllWindows()

效果如下：
在这里插入图片描述

实例2-读取视频流中姿态估计与3D绘制：

代码如下：

import cv2
import mediapipe as mp
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D
import numpy as np
from matplotlib.animation import FuncAnimation# Initialize mediapipe pose class.
mp_pose = mp.solutions.pose
pose = mp_pose.Pose()# Initialize mediapipe drawing class, useful for annotation.
mp_drawing = mp.solutions.drawing_utils# Load the video file.
cap = cv2.VideoCapture('D:/basketball.mp4')# Check if the video is opened successfully.
if not cap.isOpened():print("Error: Could not open video.")exit()fig = plt.figure(figsize=(10, 5))
ax2d = fig.add_subplot(121)
ax3d = fig.add_subplot(122, projection='3d')def update(frame_number):ret, frame = cap.read()if not ret:print("Reached the end of the video.")return# Convert the BGR image to RGB.image_rgb = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)# Process the image and detect the pose.result = pose.process(image_rgb)# Clear the previous plotsax2d.clear()ax3d.clear()# Draw the pose annotation on the image.if result.pose_landmarks:mp_drawing.draw_landmarks(frame, result.pose_landmarks, mp_pose.POSE_CONNECTIONS)# Extract the landmark points.landmarks = result.pose_landmarks.landmarkxs = [landmark.x for landmark in landmarks]ys = [landmark.y for landmark in landmarks]zs = [landmark.z for landmark in landmarks]# Plot 2D imageax2d.imshow(cv2.cvtColor(frame, cv2.COLOR_BGR2RGB))ax2d.set_title('Pose Estimation')ax2d.axis('off')# Plot 3D landmarksax3d.scatter(xs, ys, zs, c='blue', marker='o')ax3d.set_xlim([0, 1])ax3d.set_ylim([0, 1])ax3d.set_zlim([-1, 1])ax3d.set_xlabel('X')ax3d.set_ylabel('Y')ax3d.set_zlabel('Z')ax3d.set_title('3D Pose Landmarks')ani = FuncAnimation(fig, update, interval=10)plt.show()cap.release()
cv2.destroyAllWindows()

效果如下：
在这里插入图片描述
为了将三维骨骼点连接起来，可以使用 mpl_toolkits.mplot3d.art3d.Line3DCollection 来绘制骨骼连接。你需要定义这些连接的点对，并在三维图中使用它们来绘制线条。以下是更新后的代码：

import cv2
import mediapipe as mp
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D
from mpl_toolkits.mplot3d.art3d import Line3DCollection
import numpy as np
from matplotlib.animation import FuncAnimation# Initialize mediapipe pose class.
mp_pose = mp.solutions.pose
pose = mp_pose.Pose()# Initialize mediapipe drawing class, useful for annotation.
mp_drawing = mp.solutions.drawing_utils# Load the video file.
cap = cv2.VideoCapture('D:/basketball.mp4')# Check if the video is opened successfully.
if not cap.isOpened():print("Error: Could not open video.")exit()fig = plt.figure(figsize=(10, 5))
ax2d = fig.add_subplot(121)
ax3d = fig.add_subplot(122, projection='3d')def update(frame_number):ret, frame = cap.read()if not ret:print("Reached the end of the video.")return# Convert the BGR image to RGB.image_rgb = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)# Process the image and detect the pose.result = pose.process(image_rgb)# Clear the previous plotsax2d.clear()ax3d.clear()# Draw the pose annotation on the image.if result.pose_landmarks:mp_drawing.draw_landmarks(frame, result.pose_landmarks, mp_pose.POSE_CONNECTIONS)# Extract the landmark points.landmarks = result.pose_landmarks.landmarkxs = [landmark.x for landmark in landmarks]ys = [landmark.y for landmark in landmarks]zs = [landmark.z for landmark in landmarks]# Define the connections between landmarksconnections = [(0, 1), (1, 2), (2, 3), (3, 7), (0, 4), (4, 5), (5, 6), (6, 8),(9, 10), (11, 12), (11, 13), (13, 15), (15, 17), (15, 19), (15, 21),(17, 19), (12, 14), (14, 16), (16, 18), (16, 20), (16, 22), (18, 20),(11, 23), (12, 24), (23, 24), (23, 25), (24, 26), (25, 27), (26, 28),(27, 29), (28, 30), (29, 31), (30, 32)]# Create a list of 3D lineslines = [[(xs[start], ys[start], zs[start]), (xs[end], ys[end], zs[end])] for start, end in connections]# Plot 2D imageax2d.imshow(cv2.cvtColor(frame, cv2.COLOR_BGR2RGB))ax2d.set_title('Pose Estimation')ax2d.axis('off')# Plot 3D landmarks and connectionsax3d.scatter(xs, ys, zs, c='blue', marker='o')ax3d.add_collection3d(Line3DCollection(lines, colors='blue', linewidths=2))ax3d.set_xlim([0, 1])ax3d.set_ylim([0, 1])ax3d.set_zlim([-1, 1])ax3d.set_xlabel('X')ax3d.set_ylabel('Y')ax3d.set_zlabel('Z')ax3d.set_title('3D Pose Landmarks')ani = FuncAnimation(fig, update, interval=10)plt.show()cap.release()
cv2.destroyAllWindows()

在这个代码中，我们定义了 connections 列表，它包含了骨骼点之间的连接对。然后我们创建了一个 lines 列表，用于存储这些连接的三维线段，并使用 ax3d.add_collection3d(Line3DCollection(lines, colors='blue', linewidths=2)) 方法将这些线段添加到三维图中。

运行这个脚本后，三维图中不仅会显示骨骼点，还会将这些点连起来，形成完整的骨骼结构。
效果如下：
在这里插入图片描述
上面的代码看似三维图的骨骼是倒立的，你可以调整三维图的坐标显示，以使得骨骼结构显示为正常的人体姿态。可以通过设置三维图的坐标轴范围和方向来调整显示效果。以下是修改后的代码，调整了坐标轴的范围和方向，以使骨骼结构正常显示：

import cv2
import mediapipe as mp
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D
from mpl_toolkits.mplot3d.art3d import Line3DCollection
import numpy as np
from matplotlib.animation import FuncAnimation# Initialize mediapipe pose class.
mp_pose = mp.solutions.pose
pose = mp_pose.Pose()# Initialize mediapipe drawing class, useful for annotation.
mp_drawing = mp.solutions.drawing_utils# Load the video file.
cap = cv2.VideoCapture('D:/basketball.mp4')# Check if the video is opened successfully.
if not cap.isOpened():print("Error: Could not open video.")exit()fig = plt.figure(figsize=(10, 5))
ax2d = fig.add_subplot(121)
ax3d = fig.add_subplot(122, projection='3d')def update(frame_number):ret, frame = cap.read()if not ret:print("Reached the end of the video.")return# Convert the BGR image to RGB.image_rgb = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)# Process the image and detect the pose.result = pose.process(image_rgb)# Clear the previous plotsax2d.clear()ax3d.clear()# Draw the pose annotation on the image.if result.pose_landmarks:mp_drawing.draw_landmarks(frame, result.pose_landmarks, mp_pose.POSE_CONNECTIONS)# Extract the landmark points.landmarks = result.pose_landmarks.landmarkxs = [landmark.x for landmark in landmarks]ys = [landmark.y for landmark in landmarks]zs = [-landmark.z for landmark in landmarks]  # Negate the z-axis for better visualization# Define the connections between landmarksconnections = [(0, 1), (1, 2), (2, 3), (3, 7), (0, 4), (4, 5), (5, 6), (6, 8),(9, 10), (11, 12), (11, 13), (13, 15), (15, 17), (15, 19), (15, 21),(17, 19), (12, 14), (14, 16), (16, 18), (16, 20), (16, 22), (18, 20),(11, 23), (12, 24), (23, 24), (23, 25), (24, 26), (25, 27), (26, 28),(27, 29), (28, 30), (29, 31), (30, 32)]# Create a list of 3D lineslines = [[(xs[start], ys[start], zs[start]), (xs[end], ys[end], zs[end])] for start, end in connections]# Plot 2D imageax2d.imshow(cv2.cvtColor(frame, cv2.COLOR_BGR2RGB))ax2d.set_title('Pose Estimation')ax2d.axis('off')# Plot 3D landmarks and connectionsax3d.scatter(xs, ys, zs, c='blue', marker='o')ax3d.add_collection3d(Line3DCollection(lines, colors='blue', linewidths=2))ax3d.set_xlim([0, 1])ax3d.set_ylim([1, 0])  # Flip the y-axis for better visualizationax3d.set_zlim([1, -1])ax3d.set_xlabel('X')ax3d.set_ylabel('Y')ax3d.set_zlabel('Z')ax3d.set_title('3D Pose Landmarks')ani = FuncAnimation(fig, update, interval=10)plt.show()cap.release()
cv2.destroyAllWindows()