High-performance AprilTag marker detection and decoding.

kornia-apriltag is a pure Rust implementation of the AprilTag fiducial marker system. It provides robust and efficient algorithms for detecting and decoding tags from images, suitable for robotics, augmented reality, and camera calibration tasks.

• Multi-Family Support: Detects various tag families including Tag16H5, Tag25H9, Tag36H11, and Circle tags (TagCircle21H7, TagCircle49H12).
• High Performance: Optimized implementation with efficient image thresholding, segmentation, and quad fitting.
• Configurable Pipeline: Fine-tune detection parameters such as sharpening, edge refinement, and quad decimation.
• Pure Rust: No external C/C++ dependencies, ensuring easy compilation and cross-platform support.
• Strongly Typed: Integrates seamlessly with kornia-image for type-safe image processing.

Add the following to your Cargo.toml:

[dependencies]
kornia-apriltag = "0.1.0"

use kornia_apriltag::{AprilTagDecoder, DecodeTagsConfig, family::TagFamilyKind};
use kornia_image::{Image, ImageSize};
// use kornia_io::functional as F; // Assuming you have an image reader

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // 1. Configure the decoder for Tag36h11
    let config = DecodeTagsConfig::new(vec![TagFamilyKind::Tag36H11])?;

    // 2. Load an image (grayscale required)
    // let image = F::read_image_any_rgb8("tag.jpg")?;
    // let gray_image = kornia_imgproc::color::rgb_to_gray(&image)?;

    // Create dummy image for example
    let gray_image = Image::<u8, 1>::new(
        ImageSize { width: 100, height: 100 },
        vec![0u8; 10000],
    )?;

    // 3. Initialize decoder
    let mut decoder = AprilTagDecoder::new(config, gray_image.size())?;

    // 4. Decode
    let detections = decoder.decode(&gray_image)?;

    println!("Detected {} tags", detections.len());

    for detection in detections {
        println!("Found tag ID: {}", detection.id);
        println!("Center: {:?}", detection.center);
    }

    Ok(())
}

• decoder: Main decoding logic and AprilTagDecoder struct.
• errors: Error types for AprilTag detection.
• family: Tag family definitions.
• quad: Low-level quad detection algorithms.
• segmentation: Image segmentation and clustering.
• threshold: Thresholding utilities for AprilTag detection.
• union_find: Union-find data structure for connected components.
• utils: Utility functions and types.

Note: DecodeTagsConfig is a struct exported from the crate root (lib.rs), not a separate module.

You can find comprehensive examples in the examples folder of the repository:

• apriltag: Demonstration of detecting AprilTags in images using kornia-apriltag.

Contributions are welcome! This crate is part of the Kornia workspace. Please refer to the main repository for contribution guidelines.

This crate is licensed under the Apache-2.0 License.