Field Calibrator

Calibrate relative positions of Apriltags on the field

Guide

Clone repository

$ git clone --recurse-submodules https://github.com/TheHolyCows/cowlibration-field

Build

$ cmake --preset=default
$ cmake --build build

Install Python dependencies

$ pip install -r requirements.txt

Usage

1. Prepare a calibrated camera model
   • See https://github.com/TheHolyCows/cowlibration-camera for calibrating your camera
2. Record a video of the field's AprilTags
3. Run field calibrator

$ ./build/FieldCalibrator                            \
    --input-dir [input video directory path]         \
    --camera-model [input camera model path]         \
    --ideal-map [input ideal field map path]         \
    --output-file [output calibrated field map path] \
    --fps [detection fps]                            \
    --tag-size [tag size in meters]

Visualize

$ python scripts/visualize.py [ideal field map path] [observed field map path]

Example

This repo contains a sample camera model and sample field videos. The below commands run the field calibration tool on the sample data and visualizes the generated field map.

$ ./build/FieldCalibrator                                            \
    --input-dir data/input_champs_blue/                              \
    --camera-model data/camera_models/iphone_12_with_correction.json \
    --ideal-map data/field_maps/2024-crescendo.json                  \
    --output-file data/field_maps/2024-champs-blue.json              \
    --fps 15                                                         \
    --tag-size 0.1651                                                \
    --pin-tag 7

$ python scripts/visualize.py data/field_maps/2024-crescendo.json data/field_maps/2024-champs-blue.json