接收來自 ROS Topic 的影像並偵測畫面中的動作

這次來帶大家玩個基礎的應用 - 動作偵測,用自己筆電的相機再加上 OpenCV 的 API,就可以做到動作偵測並把在動的地方框起來。可以透過這篇

這次來帶大家玩個基礎的應用 - 動作偵測,用自己筆電的相機再加上 OpenCV 的 API,就可以做到動作偵測並把在動的地方框起來。可以透過這篇學習怎麼使用 ROS Topic 來接收影像並做後續的處理。

開 package 寫程式

首先來開一個 motion_detector package:

catkin_create_pkg motion_detector rospy sensor_msgs cv_bridge usb_cam/cd motion_detectorvim src/motion_detector.py

程式碼長這樣,裡面主要是用到 OpenCV 的 MOG2這個前背景分類的工具,切出來的前景就用一個框框來表示。

#!/usr/bin/env pythonimportrospyimportcv2importnumpyasnpfromcv_bridgeimportCvBridge, CvBridgeErrorfromsensor_msgs.msgimportImagekernel_elliptic_7 = cv2.getStructuringElement(cv2.MORPH_ELLIPSE, (7,7))kernel_elliptic_15 = cv2.getStructuringElement(cv2.MORPH_ELLIPSE, (15,15))area_threshold = 2000classMOG2:def__init__(self): self.fgbg = cv2.BackgroundSubtractorMOG2(history=150, varThreshold=500, bShadowDetection=True)defdetect(self,image): fgmask = self.fgbg.apply(image) cv2.morphologyEx(fgmask, cv2.MORPH_CLOSE, kernel_elliptic_7, dst=fgmask) cv2.morphologyEx(fgmask, cv2.MORPH_OPEN, kernel_elliptic_15, dst=fgmask) contours = cv2.findContours(fgmask.astype(np.uint8), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE) area_box = ((cv2.contourArea(contour), cv2.boundingRect(contour)) forcontourincontours[0]) area_box = [(area, box) for(area, box)inarea_boxifarea > area_threshold] area_box.sort(reverse=True) bounding_boxes = [((x, y), (x+w, y+h)) for_, (x, y, w, h)inarea_box[:5]]forp1, p2inbounding_boxes: cv2.rectangle(image, p1, p2, (0,255,0),2)returnimage#return fgmask #for param tuningclassMotion:def__init__(self): rospy.init_node("motion_detector_node") self.bridge = CvBridge() self.pub = rospy.Publisher('camera/visible/image', Image, queue_size=2) rospy.Subscriber("usb_cam/image_raw", Image, self.imageCallback) self.motion_detector = MOG2() rospy.spin()defimageCallback(self, image):ifself.motion_detector: cv_image = self.bridge.imgmsg_to_cv2(image, "bgr8") result_img = self.motion_detector.detect(cv_image) image = self.bridge.cv2_to_imgmsg(result_img, "bgr8")#image = self.bridge.cv2_to_imgmsg(result_img, "mono8") #for param tuning self.pub.publish(image)if__name__ =='__main__': detector = Motion()

執行程式

先把程式變成可執行的 node,接着來寫個 launch file 方便執行:

chmod +x src/motion_detector.pymkdir launchvim launch/motion_detection.launch
<launch><!-- Launch the motion detector node for image processing. --><nodepkg="motion_detector"name="MotionDetector"type="motion_detector.py"/><!-- Launch the driver node for our usb camera. --><nodename="usb_cam"pkg="usb_cam"type="usb_cam_node"output="screen"><paramname="video_device"value="/dev/video0"/><paramname="image_width"value="640"/><paramname="image_height"value="480"/><paramname="pixel_format"value="yuyv"/><paramname="camera_frame_id"value="usb_cam"/><paramname="io_method"value="mmap"/></node><nodename="rviz"pkg="rviz"type="rviz"required="true"args="-d $(find motion_detector)/rviz/motion.rviz"/></launch>

這邊想順便教大家一個技巧,你可以把 rviz 的檔案先寫好,這樣每次重新啓動 Rviz 就很方便,不用重新選想要看的資料類型。

vim rviz/motion.rviz

其實這個檔案可以直接從 Rviz 存出來,或是你也可以很 hardcore 地自己寫XD

Panels: - Class: rviz/Displays Help Height: 78 Name: Displays Property Tree Widget: Expanded: - /Global Options1 - /Status1 - /Image1 Splitter Ratio: 0.5 Tree Height: 387 - Class: rviz/Selection Name: Selection - Class: rviz/Tool Properties Expanded: - /2D Pose Estimate1 - /2D Nav Goal1 - /Publish Point1 Name: Tool Properties Splitter Ratio: 0.588679 - Class: rviz/Views Expanded: - /Current View1 Name: Views Splitter Ratio: 0.5 - Class: rviz/Time Experimental: false Name: Time SyncMode: 0 SyncSource: ImageVisualization Manager: Class: "" Displays: - Alpha: 0.5 Cell Size: 1 Class: rviz/Grid Color: 160; 160; 164 Enabled: true Line Style: Line Width: 0.03 Value: Lines Name: Grid Normal Cell Count: 0 Offset: X: 0 Y: 0 Z: 0 Plane: XY Plane Cell Count: 10 Reference Frame: <FixedFrame> Value: true - Class: rviz/Image Enabled: true Image Topic: /camera/visible/image Max Value: 1 Median window: 5 Min Value: 0 Name: Image Normalize Range: true Queue Size: 2 Transport Hint: raw Unreliable: false Value: true Enabled: true Global Options: Background Color: 48; 48; 48 Fixed Frame: map Frame Rate: 30 Name: root Tools: - Class: rviz/Interact Hide Inactive Objects: true - Class: rviz/MoveCamera - Class: rviz/Select - Class: rviz/FocusCamera - Class: rviz/Measure - Class: rviz/SetInitialPose Topic: /initialpose - Class: rviz/SetGoal Topic: /move_base_simple/goal - Class: rviz/PublishPoint Single click: true Topic: /clicked_point Value: true Views: Current: Class: rviz/Orbit Distance: 10 Enable Stereo Rendering: Stereo Eye Separation: 0.06 Stereo Focal Distance: 1 Swap Stereo Eyes: false Value: false Focal Point: X: 0 Y: 0 Z: 0 Name: Current View Near Clip Distance: 0.01 Pitch: 0.785398 Target Frame: <FixedFrame> Value: Orbit (rviz) Yaw: 0.785398 Saved: ~Window Geometry: Displays: collapsed: false Height: 668 Hide Left Dock: false Hide Right Dock: false Image: collapsed: false QMainWindow State: 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 Selection: collapsed: false Time: collapsed: false Tool Properties: collapsed: false Views: collapsed: false Width: 1200 X: 55 Y: 14

執行結果

roslaunch motion_detector motion_detection.launch

用上面的指令跑起來之後,就可以看到在動的東西被框框圈起來啦!

接收來自 ROS Topic 的影像並偵測畫面中的動作

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到底啦