导读
本期将介绍并演示基于MediaPipe的手势骨架与特征点提取步骤以及以此为基础实现手势识别的方法。
关于MediaPipe以前有相关文章介绍,可以参看下面链接:
它能做些什么?它支持的语言和平台有哪些?请看下面两张图:
我们主要介绍手势骨架与关键点提取,其他内容大家有兴趣自行学习了解。github地址:https://github.com/google/mediapipe
手势骨架提取与关键点标注:
手势识别0~6:
具体可参考下面链接:
https://google.github.io/mediapipe/solutions/hands
(1) 安装mediapipe,执行pip install mediapipe
(2) 下载手势检测与骨架提取模型,地址:
https://github.com/google/mediapipe/tree/master/mediapipe/modules/hand_landmark
(3) 代码测试(摄像头实时测试):
import cv2import mediapipe as mpfrom os import listdirmp_drawing = mp.solutions.drawing_utilsmp_hands = mp.solutions.hands
hands = mp_hands.Hands( min_detection_confidence=0.5, min_tracking_confidence=0.5)cap = cv2.VideoCapture(0)while cap.isOpened(): success, image = cap.read() if not success: print("Ignoring empty camera frame.") continue
image = cv2.cvtColor(cv2.flip(image, 1), cv2.COLOR_BGR2RGB) image.flags.writeable = False results = hands.process(image)
image.flags.writeable = True image = cv2.cvtColor(image, cv2.COLOR_RGB2BGR) if results.multi_hand_landmarks: for hand_landmarks in results.multi_hand_landmarks: mp_drawing.draw_landmarks( image, hand_landmarks, mp_hands.HAND_CONNECTIONS) cv2.imshow('result', image) if cv2.waitKey(5) & 0xFF == 27: breakcv2.destroyAllWindows()hands.close()cap.release()
输出与结果:
图片检测(可支持多个手掌):
import cv2import mediapipe as mpfrom os import listdirmp_drawing = mp.solutions.drawing_utilsmp_hands = mp.solutions.hands
# For static images:hands = mp_hands.Hands( static_image_mode=True, max_num_hands=5, min_detection_confidence=0.2)img_path = './multi_hands/'save_path = './'index = 0file_list = listdir(img_path) for filename in file_list: index += 1 file_path = img_path + filename # Read an image, flip it around y-axis for correct handedness output (see # above). image = cv2.flip(cv2.imread(file_path), 1) # Convert the BGR image to RGB before processing. results = hands.process(cv2.cvtColor(image, cv2.COLOR_BGR2RGB))
# Print handedness and draw hand landmarks on the image. print('Handedness:', results.multi_handedness) if not results.multi_hand_landmarks: continue image_hight, image_width, _ = image.shape annotated_image = image.copy() for hand_landmarks in results.multi_hand_landmarks: print('hand_landmarks:', hand_landmarks) print( f'Index finger tip coordinates: (', f'{hand_landmarks.landmark[mp_hands.HandLandmark.INDEX_FINGER_TIP].x * image_width}, ' f'{hand_landmarks.landmark[mp_hands.HandLandmark.INDEX_FINGER_TIP].y * image_hight})' ) mp_drawing.draw_landmarks( annotated_image, hand_landmarks, mp_hands.HAND_CONNECTIONS) cv2.imwrite( save_path + str(index) + '.png', cv2.flip(annotated_image, 1))hands.close()
# For webcam input:hands = mp_hands.Hands( min_detection_confidence=0.5, min_tracking_confidence=0.5)cap = cv2.VideoCapture(0)while cap.isOpened(): success, image = cap.read() if not success: print("Ignoring empty camera frame.") # If loading a video, use 'break' instead of 'continue'. continue
# Flip the image horizontally for a later selfie-view display, and convert # the BGR image to RGB. image = cv2.cvtColor(cv2.flip(image, 1), cv2.COLOR_BGR2RGB) # To improve performance, optionally mark the image as not writeable to # pass by reference. image.flags.writeable = False results = hands.process(image)
# Draw the hand annotations on the image. image.flags.writeable = True image = cv2.cvtColor(image, cv2.COLOR_RGB2BGR) if results.multi_hand_landmarks: for hand_landmarks in results.multi_hand_landmarks: mp_drawing.draw_landmarks( image, hand_landmarks, mp_hands.HAND_CONNECTIONS) cv2.imshow('result', image) if cv2.waitKey(5) & 0xFF == 27: breakcv2.destroyAllWindows()hands.close()cap.release()
总结:MediaPipe手势检测与骨架提取模型识别相较传统方法更稳定,而且提供手指关节的3D坐标点,对于手势识别与进一步手势动作相关开发有很大帮助。
其他说明:
(1) 手部关节点标号与排序定义如下图:
(2) 手部关节点坐标(x,y,z)输出为小于1的小数,需要归一化后显示到图像上,这部分可以查看上部分源码后转到定义查看,这里给出demo代码,另外Z坐标靠近屏幕增大,远离屏幕减小:
def Normalize_landmarks(image, hand_landmarks): new_landmarks = [] for i in range(0,len(hand_landmarks.landmark)): float_x = hand_landmarks.landmark[i].x float_y = hand_landmarks.landmark[i].y # Z坐标靠近屏幕增大,远离屏幕减小 float_z = hand_landmarks.landmark[i].z print(float_z) width = image.shape[1] height = image.shape[0] pt = mp_drawing._normalized_to_pixel_coordinates(float_x,float_y,width,height) new_landmarks.append(pt) return new_landmarks
(3) 基于此你可以做个简单额手势识别或者手势靠近远离屏幕的小程序,当然不仅要考虑关节点的坐标,可能还需要计算角度已经以前的状态等等,比如下面这样:
其他demo与相关代码均在知识星球主题中发布,需要的朋友可以加入获取。另外后续有时间更新C++版本也将直接发布在知识星球中。
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