Struct Detector

pub struct Detector {
    pub(crate) bufs: DetectorBufs,
    pub(crate) valid_tags: &'static [usize],
    pub(crate) points_len: AtomicUsize,
    pub(crate) lines: Vec<(usize, usize, usize, usize)>,
    pub(crate) width: usize,
    pub(crate) height: usize,
}

An AprilTag detector

This is the main entrypoint.

Fields

bufs: DetectorBufs

Raw buffers used by the detector

valid_tags: &'static [usize]

points_len: AtomicUsize

lines: Vec<(usize, usize, usize, usize)>

Checked edges (x1, y1, x2, y2)

width: usize

Width of input frames

height: usize

Height of input frames

Implementations

impl Detector

pub fn new(width: usize, height: usize, valid_tags: &'static [usize]) -> Self

Initialize a new detector for the specified dimensions

valid_tags is required for optimization and error resistance.

pub fn calc_otsu(&mut self, input: &[u8])

Calculate otsu value

Otsu’s method is an adaptive thresholding algorithm. In English: it turns a grayscale image into binary (foreground/background, black/white).

We should investigate combining the variations for unbalanced images and triclass thresholding.

pub fn process_frame(&mut self, input: &[u8])

Process an RGB frame

FAST needs a 3x3 circle around each pixel, so we only process pixels within a 3x3 pixel padding.

pub fn detect_corners(&mut self)

Run corner detection

pub unsafe fn thresh(&self, input: &[u8])

Threshold an input RGB buffer

TODO: This needs to use Self::calc_otsu.

Safety

input is treated as an RGB buffer, even if it isn’t. The caller should check that input is an RGB buffer.

pub(crate) unsafe fn process_pixel(&self, x: usize, y: usize)

Process a pixel

This should have as little overhead as possible, as it must be run hundreds of thousands of times for each frame.

Safety

(x, y) is assumed to be a valid pixel coord. The caller must make sure of this.

pub(crate) unsafe fn check_edge( &mut self, x1: usize, y1: usize, x2: usize, y2: usize, )

Check a single edge (imaginary line between two corners)

See Self::check_edges.

Safety

(x1, y1) and (x2, y2) are assumed to be a valid pixel coords. The caller must make sure of this.

pub fn check_edges(&mut self)

Perform edge checking on all detected corners

pub fn draw(&self)

Trait Implementations

impl Clone for Detector

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Drop for Detector

fn drop(&mut self)

Executes the destructor for this type.