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.

Audits

Pass

ClawScanPass

Agentic behavior and permission review.

Static analysisPass

Pattern checks against bundled files.

VirusTotalPass

Multi-engine malware detections and file reputation.

Install

openclaw skills install apriltag-detector

Pywayne AprilTag Detector

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

Quick Start

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:

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:

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