watershed_segmentation

Segments the image with the watershed algorithm (cv::watershed()) from the seed points, given by the mouse or the ~/add_seed_points topic.

opencv_apps	1.11 and later (ROS 1), 3.0.0 and later (ROS 2)
ROS	noetic, ROS One, jazzy, kilted, lyrical and later
OpenCV	any version of the distributions
Group	Segmentation, the nodes of which publish the mask or label image, ~/image of the color filters and background_subtraction, ~/label of dnn_semantic_segmentation, and ~/contours (ContourArrayStamped) of the regions of segment_objects and watershed_segmentation

Usage

# ROS 2
ros2 launch opencv_apps watershed_segmentation.launch.xml image:=/camera/image_raw debug_view:=false
# ROS 1
roslaunch opencv_apps watershed_segmentation.launch image:=/camera/image_raw debug_view:=false

Try it with the demo video

Download the input video of the demo above, publish it as image with image_publisher, and run the node on it, in the terminals:

wget https://ros-perception.github.io/opencv_apps/media/clips/ballpit.mp4
# terminal 1: publish the video as image in a loop
ros2 run image_publisher image_publisher_node ballpit.mp4 --ros-args -p publish_rate:=10.0 -r image_raw:=image
# terminal 2: run the node with the parameters of the demo
ros2 launch opencv_apps watershed_segmentation.launch.xml image:=image use_camera_info:=false
# terminal 3: run, keep it running
ros2 topic pub -r 1.5 /watershed_segmentation/add_seed_points opencv_apps/msg/Point2DArray "{points: [{x: 100.0, y: 100.0}, {x: 200.0, y: 100.0}, {x: 300.0, y: 100.0}, {x: 400.0, y: 100.0}, {x: 500.0, y: 100.0}, {x: 100.0, y: 200.0}, {x: 200.0, y: 200.0}, {x: 300.0, y: 200.0}, {x: 400.0, y: 200.0}, {x: 500.0, y: 200.0}, {x: 100.0, y: 300.0}, {x: 200.0, y: 300.0}, {x: 300.0, y: 300.0}, {x: 400.0, y: 300.0}, {x: 500.0, y: 300.0}]}"
# terminal 4: view the result
ros2 run rqt_image_view rqt_image_view /watershed_segmentation/image

See Credits of the demo videos for the license of the video.

Subscribed topics

Topic	Type
image	sensor_msgs/msg/Image
~/add_seed_points	opencv_apps/msg/Point2DArray

Published topics

Topic	Type
~/contours	opencv_apps/msg/ContourArrayStamped
~/image	sensor_msgs/msg/Image

Parameters

See also the common parameters.

Name	Type	Default (range)	Changed at run time	Description
queue_size	int	3	no, restart the node	Specigy queue_size of input image subscribers

Source

src/nodelet/watershed_segmentation_nodelet.cpp, launch/watershed_segmentation.launch.xml