Nothing Special   »   [go: up one dir, main page]
Skip to content
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

Jump to bottom

concave_hull returns nonsense results for simple polygons #1124

Open
wlinna opened this issue Dec 9, 2023 · 2 comments
Open

concave_hull returns nonsense results for simple polygons #1124

wlinna opened this issue Dec 9, 2023 · 2 comments
Labels
bug geo

Comments

@wlinna
Copy link
wlinna commented Dec 9, 2023

I'm testing concave_hull with a simple polygon, and concave_hull returns very weird results. Here are the screenshots

Original polygon
OriginalPolygon

Concave hull
FailedConcaveHull

Here's the test code

       let exterior = LineString(vec![
            Coord { x: 5.1734996, y: 1.4128553 },
            Coord { x: 5.1734996, y: 1.5378553 },
            Coord { x: -4.9266067, y: 1.5378562 },
            Coord { x: -4.9266057, y: -8.45025 },
            Coord { x: -4.8016057, y: -8.45025 },
            Coord { x: -4.8016057, y: 1.4128553 },
            Coord { x: 5.1734996, y: 1.4128553 },
        ]);
    
        let polygon = Polygon::new(exterior.clone(), vec![]);
        let hull = polygon.concave_hull(0.5); // Whether the concavity is 0.5 or 4.0 doesn't seem to matter

I'm using geo 0.27.0 with Rustc 1.72
@wlinna
Copy link
Author
wlinna commented Apr 27, 2024

I tried this again with both geo 0.27 and geo 0.28 , and it looks like nothing changed with concave hull itself. Both versions result in following coordinates

-4.9266057 -8.45025
-4.8016057 -8.45025
5.1734996 1.4128553
5.1734996 1.5378553
-4.9266067 1.5378562
-4.9266057 -8.45025

However, I'm not sure anymore how I produced the original 3D model of the concave hull. When I generate it now, it looks like this

imagen

I checked the printed coordinates visually one by one, and they correspond with the generated triangle mesh.

So at least the algorithm produces a convex hull. But I can't make it produce the original shape.

@kirillolenev-dm
Copy link
kirillolenev-dm commented Nov 2, 2024 •
edited
Loading

Any updates about that? I have a similar experience when concave_hull provides something not close to expected result, concavity param doesn't change much.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Assignees
No one assigned
Labels
bug geo
Projects
None yet
Milestone
No milestone
Development

No branches or pull requests
3 participants
@frewsxcv @wlinna @kirillolenev-dm