AprilTags are visual markers designed for easy detection and identification by computer vision systems. These square tags feature a unique black and white pattern that allows cameras and software to quickly recognize them and determine their precise position and orientation in 3D space.
There are 38 different AprilTags, numbered 0 through 37. For a printable copy of these AprilTags, go here.
Each AprilTag has an identifiable ID number that allows the AI Vision Sensor to differentiate between them. This allows the AprilTags to be used for navigation around a field or identify points of interest.
Go here for more information on how to use data about detected AprilTags in your Blocks, Python, or C++ VEXcode projects.
Enable AprilTag Detection
To be able to detect AprilTags, its Detection Mode must first be enabled in the AI Vision Utility.
Select Configure in the AI Vision Sensor's device menu.
The AI Vision Utility will open. Select the toggle underneath AprilTags to turn on the AprilTag Detection Mode.
Select Close to exit the AI Vision Utility.
You will see the new AprilTag Detection Mode be set to on.
Select Done to save your changes to the AI Vision Sensor's configuration.
AprilTag Specific Data
The AI Vision Sensor collects and reports specific data related to April Tags.
ID refers to the unique Tag ID of each April Tag, which can be seen in the upper left corner of the Tag.
Angle refers to the rotational angle of the sensor in relation to the AprilTag. It is reported in degrees from 0-359.
Coding with AprilTags in VEXcode EXP
To see the AI Vision Sensor interact with AprilTags in real time, use the Detecting AprilTags (AI Vision) Example Project found within VEXcode EXP.
To learn how to use Example Projects in VEXCode EXP, go here.