Run basic OCR with ocr_service

The ocr_service sample application enables a service that provides the Optical Character Recognition (OCR) function. It captures the image topic from the ROS system and publishes the result with the ocr_topic.

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Pipeline flow for ocr_service

This figure shows the basic messages and data transfer channels, with the relevant client/server and ROS node.

Figure : The ocr_service pipeline

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ROS nodes used in the ocr_service pipeline

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ROS topics used in the ocr_service pipeline

ROS topic	Message type	Published/Subscribed by	Description
/image_topic_name	<sensor_msgs.msg.Image>	Subscribe to images from other nodes	The image to be processed.
/ocr_image_topic_name	<std_msgs.msg.String>	Published by ocr-rosnode	Publishes the OCR result.

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Prerequisites

You have Set up the device according to Set up the environment for running sample applications.

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Run out-of-the-box ocr_service

1. Start three terminals, and run the following commands in each terminal to set up QIR SDK and ROS2 environment on the device. Value range of ROS_DOMAIN_ID: [0, 232]
   ssh root@[ip-addr]
   (ssh) source /usr/share/qirp-setup.sh
   (ssh) export ROS_DOMAIN_ID=xx
   
2. In terminal 1, launch ocr_server.
   (ssh) ros2 run ocr_service ocr_server
   
3. In terminal 2, push an image to the device and run the ocr_testnode.
   scp  qirp-samples/platform/ocr_service/scripts/digital_720p.png root@[ip-addr]:/opt
   (ssh) ros2 run ocr_service ocr_testnode --topic imagetest --picture /opt/digital_720p.png
   
4. In terminal 3, run the ocr_client.
   (ssh) ros2 run ocr_service ocr_client imagetest
   
   You will see the following log:

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Build and run ocr_service

1. Build ocr_msg and ocr_service provided by the QIR SDK on the host.
   cd <qirp_decompressed_workspace>
   source setup.sh
   cd qirp-samples/platform/ocr_service
   colcon build --merge-install --cmake-args ${CMAKE_ARGS}
   
2. Push ocr_msg and ocr_service to the device.
   cd qirp-samples/platform/ocr_service/install
   tar -zcvf ocr_service.tar.gz lib/ share/
   ssh root@[ip-addr]
   scp ocr_service.tar.gz root@[ip-addr]:/opt
   ssh ssh root@[ip-addr]
   (ssh) tar --no-overwrite-dir --no-same-owner -zxf /opt/ocr_service.tar.gz -C /usr/ros/jazzy/
   scp qirp-samples/platform/ocr_service/scripts/digital_720p.png root@[ip-addr]:/opt
   
3. Run ocr_service on the device with the steps in Run out-of-the-box ocr_service.