fiducial-detection.md

Example of Fiducial Detection

Raspicam

• We use a RaspberryPi v1 camera whose full documentation can be found at Raspicam Docs, this also includes hardware and software specs

• Additional information on how to install Raspicam hardware can be found at Raspicam Installation

AprilTags

• We use the pupil_apriltags package to detect fiducials in the Raspicam image so full documentation for the AprilTags can be found at Pupil AprilTags

• The package works by taking the camera parameters, fiducial size and family, and additional fiducial detection parameters and creating a detector class which contains a detect method that inputs a camera frame and outputs a list of detected fiducials

• In order to print new apriltags you have to follow the instructions at AprilTag Generation and Premade AprilTags

Parameters and Tuning

• The params.yaml file contains all of the fiducial vision parameters

• The camera parameters which are used in the params.yaml file were found online in the raspicam section

• The size of the fiducial in meters can be adjusted by printing out new fiducials of a larger size

Transformation Math

• The src/transforms.py and src/geometry.py contain the methods used for transforming the fiducial detection results into easier to work with translations and rotations

• Also, parameters in params.yaml are used to slightly adjust the detection results after transformation

Fiducial Tag Families