Comments (7)
Polygon::new
can result in an invalid polygon. š This is back to the validity thing again.
Personally I think that the simplification algorithm should return the geometry type, rather than an Option. Allow the caller to call the future .is_valid()
function on it.
- PostGIS's
ST_Simplify
can return invalid polygons. - In PostGIS there are some ways to make some invalid geometries valid again (e.g.
ST_MakeValid
or theST_Buffer(geom, 0)
trick). rust-geo might have that later, in which case an invalid polygon from simplification could be "fixed" later. If we returned an Option, then you would never have the chance to return an invalid polygon. - Some software can work with invalid polygons. I think mapnik is able to draw some invalid polygons.
from geo.
I've been looking at R-tree implementations in Rust again since this came up, and I'm making good progress with Spade's R* implementation, now that I've managed to implement the PointN
trait for Point. I've been working on implementing the technique from here (See WIP here).
If / when that lands, I'm still in favour of returning an Option
or Result
from anything that can produce invalid geometries. Returning one of these doesn't preclude you from trying to fix the geometry yourself, it just gives you the choice between using an unwrap
and taking your chances, or implementing your own fix. We should probably still benchmark a validity check, but unless it's hugely expensive, I think we should be erring on the side of flexible safety.
from geo.
Currently, I'm in favor of returning Option
/Result
types for methods/constructors that can return invalid geometries. At least for validation, right now, I'm envisioning something along the lines of:
impl<T: Float> LineString<T> {
fn from_vec(v: Vec<T>) -> Result<LineString> { .. }
/// << insert big disclaimer here >>
fn from_vec_unchecked(v: Vec<T>) -> LineString { .. }
}
from geo.
Here's a simple case (epsilon = 1.0) simplifying a Polygon exterior ring that results in a ring with only two points:
Before:
LineString([Coord { x: 42.59023437500002, y: 15.303417968749995 }, Coord { x: 42.558691406250006, y: 15.281201171874995 }, Coord { x: 42.54902343750001, y: 15.320068359375 }, Coord { x: 42.56972656250002, y: 15.407324218749991 }, Coord { x: 42.60234375000002, y: 15.432519531249994 }, Coord { x: 42.62451171875, y: 15.36796875 }, Coord { x: 42.610449218750006, y: 15.332275390625 }, Coord { x: 42.59023437500002, y: 15.303417968749995 }])
After:
LineString([Coord { x: 42.59023437500002, y: 15.303417968749995 }, Coord { x: 42.59023437500002, y: 15.303417968749995 }])
from geo.
In the case of polygon rings, could we just break once the LineString
ring is 3 coordinates?
from geo.
I think so (that's what we do in visvalingam_preserve
ā actually it's 4 coordinates there, but no matter) but is there a perf hit for checking the length on every loop?
from geo.
Here's my fix attempt: #943
from geo.
Related Issues (20)
- Helper for converting between Mercator and Euclidean coordinates HOT 1
- getting one of the closest point for `Closest::Indeterminate` HOT 2
- Consider applying for support from OSGEO or OGC?
- Algorithm to partition a polygon (convex decomposition) using the Hertel-Mehlhorn algorithm HOT 1
- Documentation for monotone-decomposition
- Panic on clip operation HOT 2
- Iām confused about the clip API. Could the operations be more clearly documented? HOT 6
- Add a buffer feature like turfjs HOT 1
- panic on polygon union HOT 1
- Replace HaversineIntermediate with HaversineLineInterpolatePoint and HaversineDensify HOT 2
- Segementize LineString into arbitrary lengths. HOT 4
- performance for multipolygon contains much worse than for geos HOT 16
- Note availability of rstar spatial index early in docs HOT 1
- Merge geo-types and geo crate HOT 5
- BooleanOps panic in `Snake::into_ring`
- Boolean difference causes panic: `segment not found` HOT 6
- Enhance SpadeTriangulation API
- Semantics for AffineTransform composition is reversed HOT 5
- `bounding_rect` comsume a lot of cpu?? HOT 23
- Boolean ops should be available between differing geometry types
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from geo.