Run basic OCR with ocr_service - Qualcomm Dragonwing Documentation

Pipeline flow for `ocr_service`

The following figure shows the pipeline flow among the relevant client/server and ROS nodes, with the basic messages and data transfer channels.

ROS nodes used in the `ocr_service` pipeline

The following table lists the ROS nodes used in the ocr_service pipeline and describes what each node does.

ROS node	Description
`OCR_CLIENT`	Sends the optical character recognition (OCR) request to `ocr_server` and gets the server result.
`OCR_SERVER`	Gets the OCR request from `ocr_server` , and forks the `ocr_rosnode` according to the request.
`OCR_ROSNODE`	Subscribes to the image topic according to the request.

ROS topics used in the `ocr_service` pipeline

The following table lists the ROS topics used in the ocr_service pipeline, with the message type and the publisher of each topic.

ROS topic	Type	Published by
`/image_topic_name`	`< sensor_msgs.msg.Image >`	Any ROS node
`/ocr_image_topic_name`	`< std_msgs/msg/String >`	`ocr-rosnode` node

Prerequisites

You have set up the device, installed ROS2 Jazzy and the Qualcomm Intelligent Robotics (QIR) SDK on the device according to Install the QIR SDK.

Run out-of-the-box `ocr_service`

Run ocr_service with the following commands:

Run ocr_service

source /opt/ros/jazzy/setup.bash
ros2 run ocr_service ocr_server
ros2 run ocr_service ocr_testnode --topic <image_topic> --picture <image_path>
ros2 run ocr_service ocr_client <image_topic>

Example

This example shows the commands you can run in the three terminals:

In terminal 1:

Start the OCR server

source /opt/ros/jazzy/setup.bash
ros2 run ocr_service ocr_server

In terminal 2:

Publish a test image

source /opt/ros/jazzy/setup.bash
scp <pic_path>/test.png ubuntu@IP:/home/ubuntu/image
ros2 run ocr_service ocr_testnode --topic test --picture /home/ubuntu/image/test.png

In terminal 3:

Run the OCR client

source /opt/ros/jazzy/setup.bash
ros2 run ocr_service ocr_client test

​Pipeline flow for ocr_service

​ROS nodes used in the ocr_service pipeline

​ROS topics used in the ocr_service pipeline

​Prerequisites

​Run out-of-the-box ocr_service

​Example