|
|
To determine whether a GPS coordinate is within an electronic fence, which is a convex polygon formed by multiple GPS coordinates, we can use the Ray Casting algorithm. The main idea is to draw a line segment from the coordinate to a point outside the polygon, and count how many edges it intersects. If the number of intersections is even, the coordinate is outside the polygon, otherwise it's inside.
This algorithm can accurately judge whether the coordinate is within the convex polygon. However, since the Earth is not a flat plane, if the GPS data in the vertices of the polygon crosses the change line (the boundary between 360 degrees and -360 degrees), it may cause problems, and may need to add or subtract in some corner data.
So, the implementation process is to traverse each edge of the polygon in turn, and determine whether the connection point of the coordinate and the edge is on the left or right of the edge vector. If it's on the right, it's considered to be intersected, otherwise it's not. When the last edge is judged, if the result is intersect, it means that the coordinate is outside the polygon, otherwise it's inside.
In conclusion, through the above algorithm, we can determine whether a GPS coordinate is within a given convex polygon (electronic fence). |
|
发表于 2024-3-20 16:01:02
收藏
楼主