Welcome to Raspberry Pi 5 repository
10.Edge detection algorithm
10.Edge detection algorithm
10.1. Use
Source code launch file path：/opt/ros/noetic/share/opencv_apps/launch
Step 1: Start the camera
roslaunch dofbot_visual opencv_apps.launch img_flip:=false
img_flip parameter: whether the image needs to be flipped horizontally, the default is false.
[usb_cam-test.launch] file opens the [web_video_server] node by default, and you can directly use the [IP:8080] web page to view images in real time.
Step 2: Start the corner detection function of Opencv_apps
xxxxxxxxxxroslaunch opencv_apps edge_detection.launch # Edge detection algorithmEach functional case will have a parameter [debug_view], Boolean type, whether to use Opencv to display images, which is displayed by default.
If no display is required, set it to [False], for example
xxxxxxxxxxroslaunch opencv_apps contour_moments.launch debug_view:=FalseHowever, after starting in this way, some cases cannot be displayed in other ways, because in the source code, some [debug_view] is set to [False], which will turn off image processing.
10.2 Display method
rqt_image_view
Enter the following command to select the corresponding topic
xxxxxxxxxxrqt_image_view
opencv
The system displays it by default, no need to do anything.
Web viewing
(Same as under LAN) Enter IP+port in the browser, for example:
xxxxxxxxxx192.168.2.116:8080
For specific IP, use your current virtual machine IP.
10.3 Effect display
There will be a topic for subscribing images and publishing images.
| Parameter | Type | Default | Analyze |
|---|---|---|---|
| ~use_camera_info | bool | true | Subscribe to the topic [camera_info] to get the default coordinate system ID, otherwise use the image information directly. |
| ~debug_view | bool | false | Whether to create a window to display the node image |
| ~edge_type | int | 0 | Specify the edge detection method: 0: Sobel operator, 1: Laplacian operator, 2: Canny edge detection |
| ~canny_threshold1 | int | 100 | Specify the second canny threshold |
| ~canny_threshold2 | int | 200 | Specify the first canny threshold |
| ~apertureSize | int | 3 | Aperture size of the Sobel operator. |
| ~apply_blur_pre | bool | True | Whether to apply blur() to the input image |
| ~postBlurSize | double | 3.2 | Input image aperture size |
| ~apply_blur_post | bool | False | Whether to apply GaussianBlur() to the input image |
| ~L2gradient | bool | False | Canny's parameters |
| ~queue_size | int | 3 | Queue size |
Effect picture:
Node picture:
