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Detection of AprilTags and QR codes
Description: This tutorial shows how to use the TagDetect module of the rc_visard to detect AprilTags and QR codes.Keywords: rc_visard, tagdetect, rosservice, Web GUI
Tutorial Level: BEGINNER
Contents
Goal
The goal of this tutorial is to show how to trigger the detection of AprilTags and QR Codes through rosservice calls and the Web GUI of the rc_visard.
Before we start
In order to go through this tutorial, the following prerequisites should be met:
Prerequisites
The rc_visard is running the latest firmware and the rc_visard’s license includes the TagDetect module to be used (AprilTag or QR Code). This can be verified on the Web GUI’s System page.
The Web GUI can be accessed using rcdiscover.
Installation
Install the TagDetect client:
$ sudo apt-get install ros-melodic-rc-tagdetect-client
Setting up the scene
To verify the maximum distance from which a tag can be detected, go to the Tag reading section of the rc_visard's manual.
Detection by the Web GUI
For trying out the tag detection from the Web GUI, simply go to the correspondent TagDetect module on the Modules page. There you can find the interface where you can optionally add the tag family and run the detection by clicking on "Detect" in the Try Out section.
Detection by rosservice call
In order to use rosservices for tag detection, the tag detection client has to be running and then a call to the corresponding rosservice has to be made. This can be done by using the following commands:
The parameter needed is either the device's id or its IP address. For illustration purposes, both are being displayed.
The device id can be either the rc_visard's serial number or its user defined name.
For QR-Code detection:
$ rosrun rc_tagdetect_client rc_qr_node _device:=<device id>
$ rosservice call /rc_qr_code_detect/detect "tags: []"
For April-Tag detection:
$ rosrun rc_tagdetect_client rc_april_node _device:=<device id>
$ rosservice call /rc_april_tag_detect/detect "tags: []"
