Run basic OCR with ocr_service - Qualcomm Dragonwing Documentation

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.

Pipeline flow for `ocr_service`

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

Figure : ocr_service pipeline

ROS nodes used in the `ocr_service` pipeline

ROS node	Description
`OCR_CLIENT`	Sends the 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

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.

Prerequisites

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

Run out-of-the-box `ocr_service`

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Set up QIR SDK and ROS2 environment on the device

Start three terminals, and run the following commands in each terminal.Value range of ROS_DOMAIN_ID: [0, 232]

ssh root@[ip-addr]

SSH Session

source /usr/share/qirp-setup.sh
export ROS_DOMAIN_ID=xx

Launch ocr_server

In terminal 1, launch ocr_server.

SSH Session

ros2 run ocr_service ocr_server

Push an image and run ocr_testnode

In terminal 2, push an image to the device and run the ocr_testnode.

wget https://raw.githubusercontent.com/qualcomm-qrb-ros/ocr_service/stable/1.0.0/scripts/digital_720p.png -O digital_720p.png
scp digital_720p.png root@[ip-addr]:/opt

SSH Session

ros2 run ocr_service ocr_testnode --topic imagetest --picture /opt/digital_720p.png

Run ocr_client

In terminal 3, run the ocr_client.

SSH Session

ros2 run ocr_service ocr_client imagetest

You will see the following log:

Build and run `ocr_service`

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Build ocr_msg and ocr_service on the host

cd <qirp_decompressed_workspace>
source setup.sh
cd qirp-samples/platform/ocr_service
colcon build --merge-install --cmake-args ${CMAKE_ARGS}

Push ocr_msg and ocr_service to the device

cd <qirp_decompressed_workspace>
cd qirp-samples/platform/ocr_service/install
tar -zcvf ocr_service.tar.gz lib/ share/
scp ocr_service.tar.gz root@[ip-addr]:/opt
ssh root@[ip-addr]

SSH Session

tar --no-overwrite-dir --no-same-owner -zxf /opt/ocr_service.tar.gz -C /usr/ros/jazzy/

wget https://raw.githubusercontent.com/qualcomm-qrb-ros/ocr_service/stable/1.0.0/scripts/digital_720p.png -O digital_720p.png
scp digital_720p.png root@[ip-addr]:/opt

Run ocr_service

Run ocr_service on the device with the steps in Run out-of-the-box ocr_service.

​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

​Build and run ocr_service

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`

Build and run `ocr_service`