Skip to content

fix(hough): make intersection_points() more general and stable #742

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
bioinformatist wants to merge 1 commit into
base: main
Choose a base branch
from
Open

fix(hough): make intersection_points() more general and stable #742

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
39 changes: 23 additions & 16 deletions src/hough.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -137,57 +137,64 @@ pub fn intersection_points(
let w = image_width as f32;
let h = image_height as f32;

// Vertical line
if m == 0 {
let theta = (m as f32).to_radians();
let (sin, cos) = theta.sin_cos();

// Vertical line, use sin for generality (there's no garantee that angle is between 0 and 180)
if sin.abs() < f32::EPSILON {
return if r >= 0.0 && r <= w {
Some(((r, 0.0), (r, h)))
} else {
None
};
}

// Horizontal line
if m == 90 {
// Horizontal line, ditto
if cos.abs() < f32::EPSILON {
return if r >= 0.0 && r <= h {
Some(((0.0, r), (w, r)))
} else {
None
};
}

let theta = (m as f32).to_radians();
let (sin, cos) = theta.sin_cos();

let right_y = cos.mul_add(-w, r) / sin;
let left_y = r / sin;
let bottom_x = sin.mul_add(-h, r) / cos;
let top_x = r / cos;

let eps = 1e-6;

let mut start = None;

if right_y >= 0.0 && right_y <= h {
let right_intersect = (w, right_y);
if right_y >= -eps && right_y <= h + eps {
// It's necessary: we allow eps during the check, but clamp for the actual result
let clamped_y = right_y.clamp(0.0, h);
let right_intersect = (w, clamped_y);
start = Some(right_intersect);
}

if left_y >= 0.0 && left_y <= h {
let left_intersect = (0.0, left_y);
if left_y >= -eps && left_y <= h + eps {
let clamped_y = left_y.clamp(0.0, h);
let left_intersect = (0.0, clamped_y);
if let Some(s) = start {
return Some((s, left_intersect));
}
start = Some(left_intersect);
}

if bottom_x >= 0.0 && bottom_x <= w {
let bottom_intersect = (bottom_x, h);
if bottom_x >= -eps && bottom_x <= w + eps {
let clamped_x = bottom_x.clamp(0.0, w);
let bottom_intersect = (clamped_x, h);
if let Some(s) = start {
return Some((s, bottom_intersect));
}
start = Some(bottom_intersect);
}

if top_x >= 0.0 && top_x <= w {
let top_intersect = (top_x, 0.0);
if top_x >= -eps && top_x <= w + eps {
let clamped_x = top_x.clamp(0.0, w);
let top_intersect = (clamped_x, 0.0);
if let Some(s) = start {
return Some((s, top_intersect));
}
Expand All @@ -209,7 +216,7 @@ mod tests {
(None, None) => {}
(Some(ps), Some(qs)) => {
let points_eq = |p: (f32, f32), q: (f32, f32)| {
(p.0 - q.0).abs() < 1.0e-6 && (p.1 - q.1).abs() < 1.0e-6
(p.0 - q.0).abs() < 1.0e-5 && (p.1 - q.1).abs() < 1.0e-5
};

match (points_eq(ps.0, qs.0), points_eq(ps.1, qs.1)) {
Expand Down
Loading