Create README.md from Wiki content #342
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ahcorde
requested changes
Feb 7, 2025
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| `polled_camera` defines the ROS interface that client nodes use to request images from a polling camera driver node (e.g. [prosilica_camera](https://index.ros.org/p/prosilica_camera/)). The protocol is: | ||
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| * The camera driver advertises a service call `<camera>/request_image` of type [polled_camera/GetPolledImage](http://www.ros.org/doc/api/polled_camera/html/srv/GetPolledImage.html). |
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link is for ROS 1, maybe use this one https://github.com/ros-perception/image_common/blob/rolling/polled_camera/srv/GetPolledImage.srv ?
| * The camera driver advertises a service call `<camera>/request_image` of type [polled_camera/GetPolledImage](http://www.ros.org/doc/api/polled_camera/html/srv/GetPolledImage.html). | ||
| * The client calls the service, specifying an output namespace. | ||
| * On receiving a request, the driver captures an image and returns its time stamp in the service response. | ||
| * The driver publishes (latching) the [sensor_msgs/Image](http://www.ros.org/doc/api/sensor_msgs/html/msg/Image.html) and [sensor_msgs/CameraInfo](http://www.ros.org/doc/api/sensor_msgs/html/msg/CameraInfo.html) to `<response_namespace>/image_raw` and `<response_namespace>/camera_info`. |
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Same here https://github.com/ros2/common_interfaces/blob/rolling/sensor_msgs/msg/Image.msg and https://github.com/ros2/common_interfaces/blob/rolling/sensor_msgs/msg/CameraInfo.msg
You might use this other one https://docs.ros2.org/foxy/api/sensor_msgs/msg/Image.html ? but rolling is not working.
| There are several reasons for publishing images to topics instead of returning them from the service call: | ||
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| * **Consistency:** Client-side processing is always performed in an image callback, regardless of what type of camera is used. | ||
| * **Visibility:** Topics can be monitored in [image_view](https://index.ros.org/p/image_view/) or [rviz](https://index.ros.org/p/rviz/). |
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| * **Consistency:** Client-side processing is always performed in an image callback, regardless of what type of camera is used. | ||
| * **Visibility:** Topics can be monitored in [image_view](https://index.ros.org/p/image_view/) or [rviz](https://index.ros.org/p/rviz/). | ||
| * **Reproducibility:** Topics can be [bagged](https://index.ros.org/p/rosbag/) and played back later. |
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| * **Consistency:** Client-side processing is always performed in an image callback, regardless of what type of camera is used. | ||
| * **Visibility:** Topics can be monitored in [image_view](https://index.ros.org/p/image_view/) or [rviz](https://index.ros.org/p/rviz/). | ||
| * **Reproducibility:** Topics can be [bagged](https://index.ros.org/p/rosbag/) and played back later. | ||
| * **Compression:** Can take advantage of [image_transport](https://index.ros.org/p/image_transport/) to compress images, if desired. |
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| ```bash | ||
| # Poll "my_camera" at 5 Hz, publishing in namespace my_polled_output/. | ||
| $ poller 5 camera:=my_camera output:=my_polled_output |
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is this correct ?
ros2 run polled_camera poller 5 camera:=my_camera output:=my_polled_output
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| Published Topics | ||
| * <output>/image_raw (sensor_msgs/Image) | ||
| Image topic, actually published by the camera driver. output should be remapped by the user. | ||
| * <output>/camera_info (sensor_msgs/CameraInfo) | ||
| Info topic, actually published by the camera driver. output should be remapped by the user. | ||
| Services Called | ||
| * <camera>/request_image (polled_camera/GetPolledImage) | ||
| The camera driver's polled image service. camera should be remapped by the user to the camera namespace. |
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Suggested change
| Published Topics | |
| * <output>/image_raw (sensor_msgs/Image) | |
| Image topic, actually published by the camera driver. output should be remapped by the user. | |
| * <output>/camera_info (sensor_msgs/CameraInfo) | |
| Info topic, actually published by the camera driver. output should be remapped by the user. | |
| Services Called | |
| * <camera>/request_image (polled_camera/GetPolledImage) | |
| The camera driver's polled image service. camera should be remapped by the user to the camera namespace. | |
| Published Topics | |
| * `<output>/image_raw` ([sensor_msgs/Image](https://github.com/ros2/common_interfaces/blob/rolling/sensor_msgs/msg/Image.msg)) | |
| Image topic, actually published by the camera driver. output should be remapped by the user. | |
| * `<output>/camera_info` ([sensor_msgs/CameraInfo](https://github.com/ros2/common_interfaces/blob/rolling/sensor_msgs/msg/CameraInfo.msg)) | |
| Info topic, actually published by the camera driver. output should be remapped by the user. | |
| Services Called | |
| * `<camera>/request_image` ([polled_camera/GetPolledImage](https://github.com/ros-perception/image_common/blob/rolling/polled_camera/srv/GetPolledImage.srv)) | |
| The camera driver's polled image service. camera should be remapped by the user to the camera namespace. |
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Pulling from: https://wiki.ros.org/polled_camera#preview