Pywayne Cv Apriltag Detector

AprilTag corner detection for camera calibration and pose estimation. Use when working with pywayne.cv.apriltag_detector module to detect AprilTag fiducial markers in images, with automatic library installation via gettool, drawing detection results with corners and IDs, and support for both file paths and numpy arrays.

Pywayne AprilTag Detector

This module detects AprilTag fiducial markers for camera calibration and pose estimation.

Quick Start

python

from pywayne.cv.apriltag_detector import ApriltagCornerDetector

# Create detector
detector = ApriltagCornerDetector()

# Detect from file path
detections = detector.detect('test.png', show_result=True)

# Detect from numpy array
import cv2
image = cv2.imread('test.png')
detections = detector.detect(image)

Detection Methods

detect()

Detect AprilTags in an image:

python

detections = detector.detect(
    image,           # File path, Path object, or numpy array
    show_result=False  # Show visualization window
)

Returns list of detection results with:

• id: Tag ID
• hamming_distance: Detection confidence
• center: Tag center coordinates (x, y)
• corners: 4 corner coordinates

detect_and_draw()

Detect AprilTags and draw results on original image:

python

result_image = detector.detect_and_draw(image)
cv2.imshow('Detection Result', result_image)
cv2.waitKey(0)

Visualization includes:

• Green polygon outlines
• Red corner circles
• Red ID labels at tag centers

Requirements

• cv2 (OpenCV) - Image processing
• numpy - Array operations
• gettool - Downloads apriltag_detection library automatically

Library Installation

The detector automatically checks for and installs the apriltag_detection library using gettool if not found.

Detection Result Format

Each detection contains:

Field	Description
id	Tag identifier
hamming_distance	Hamming distance (lower = more confident)
center	Tag center as (x, y) tuple
corners	4 corner coordinates as [(x1, y1), (x2, y2), (x3, y3), (x4, y4)]

Notes

• Supports both grayscale and BGR images
• Automatic grayscale conversion for detection
• Visualization sizes scale with image dimensions
• Uses AprilTag 36h11 tag family