[英]How to split a JTS polygon
I have a big polygon and I want to find intersecting features with the polygon but since polygon is too big, I am getting timeout exception.我有一个大多边形,我想找到与多边形相交的特征,但由于多边形太大,我遇到超时异常。
I was trying to look into JTS methods but couldn't get how to use it.我试图研究 JTS 方法,但不知道如何使用它。
final List<Coordinate> coordinates = List.of(new Coordinate(0, 0), new Coordinate(-1, 1),
new Coordinate(1, 3), new Coordinate(2, 3), new Coordinate(3, 1), new Coordinate(0, 0));
final GeometryFactory factory = new GeometryFactory();
final Polygon polygon = factory.createPolygon(coordinates.toArray(new Coordinate[0]));
final Geometry envelope = polygon.getEnvelope();
Can someone give me pointers on how to split the polygon object?有人可以指导我如何拆分多边形 object 吗?
There are many (an infinite number) ways to split a polygon, but this is how I would do it, by calculating the mid lines of the envelope and intersecting the new envelopes against the polygon.有许多(无数种)方法可以分割多边形,但我会这样做,通过计算包络线的中线并将新包络线与多边形相交。
public List<Geometry> split(Polygon p) {
List<Geometry> ret = new ArrayList<>();
final Envelope envelope = p.getEnvelopeInternal();
double minX = envelope.getMinX();
double maxX = envelope.getMaxX();
double midX = minX + (maxX - minX) / 2.0;
double minY = envelope.getMinY();
double maxY = envelope.getMaxY();
double midY = minY + (maxY - minY) / 2.0;
Envelope llEnv = new Envelope(minX, midX, minY, midY);
Envelope lrEnv = new Envelope(midX, maxX, minY, midY);
Envelope ulEnv = new Envelope(minX, midX, midY, maxY);
Envelope urEnv = new Envelope(midX, maxX, midY, maxY);
Geometry ll = JTS.toGeometry(llEnv).intersection(p);
Geometry lr = JTS.toGeometry(lrEnv).intersection(p);
Geometry ul = JTS.toGeometry(ulEnv).intersection(p);
Geometry ur = JTS.toGeometry(urEnv).intersection(p);
ret.add(ll);
ret.add(lr);
ret.add(ul);
ret.add(ur);
return ret;
}
This gives this for your polygon:这为您的多边形提供了这个:
And if you call it again on that output:如果您在 output 上再次调用它:
In a production setting you'd want some error checking to make sure you can handle the point that's generated.在生产设置中,您需要进行一些错误检查以确保您可以处理生成的点。
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