Point in Polygon

[aaronzedwick]

Proposed new feature or change:

Add a function to check if a point is inside a polygon. Currently a pole point in polygon is implemented, possibly modify it and make a similar function? That function makes a reference edge using the point and the equator, which wouldn't work with all points.

[philipc2]

We need to make sure that we implement the point-in-polygon algorithm for spherical geometry. There are dozens of implementations for standard planar geometry (shapely is the most obvious one), but these wouldn't be ideal.

[aaronzedwick]

We need to make sure that we implement the point-in-polygon algorithm for spherical geometry. There are dozens of implementations for standard planar geometry (shapely is the most obvious one), but these wouldn't be ideal.

That’s why I mentioned @hongyuchen1030 I believe it works on spherical geometry.

[hongyuchen1030]

We need to make sure that we implement the point-in-polygon algorithm for spherical geometry. There are dozens of implementations for standard planar geometry (shapely is the most obvious one), but these wouldn't be ideal.

That’s why I mentioned @hongyuchen1030 I believe it works on spherical geometry.

Unfortunately, they don't. And it is a complicated problem to solve on the spherical geometry. I remember we have already had such a discussion a long time ago. For the recent one, please see my comments here #898 (comment)

How to detect if a point is inside a face on the spherical surface. (I know the immediate answer is ray-casting, but we are on the spherical surface, so the ray will go back!)

for now, I can only come up with the pole_in_polygon that checks pole point only. With some modification, it might be used for a general case. Again this problem is more complicate on the sphere than on the planar surface

[aaronzedwick]

We need to make sure that we implement the point-in-polygon algorithm for spherical geometry. There are dozens of implementations for standard planar geometry (shapely is the most obvious one), but these wouldn't be ideal.

That’s why I mentioned @hongyuchen1030 I believe it works on spherical geometry.

Unfortunately, they don't. And it is a complicated problem to solve on the spherical geometry. I remember we have already had such a discussion a long time ago. For the recent one, please see my comments here #898 (comment)

How to detect if a point is inside a face on the spherical surface. (I know the immediate answer is ray-casting, but we are on the spherical surface, so the ray will go back!)

for now, I can only come up with the pole_in_polygon that checks pole point only. With some modification, it might be used for a general case. Again this problem is more complicate on the sphere than on the planar surface

They don’t? I thought your pole inside polygon worked on a sphere. Would it not work in the general case? Any ideas on how to make it general?

[hongyuchen1030]

We need to make sure that we implement the point-in-polygon algorithm for spherical geometry. There are dozens of implementations for standard planar geometry (shapely is the most obvious one), but these wouldn't be ideal.

That’s why I mentioned @hongyuchen1030 I believe it works on spherical geometry.

Unfortunately, they don't. And it is a complicated problem to solve on the spherical geometry. I remember we have already had such a discussion a long time ago. For the recent one, please see my comments here #898 (comment)

How to detect if a point is inside a face on the spherical surface. (I know the immediate answer is ray-casting, but we are on the spherical surface, so the ray will go back!)

for now, I can only come up with the pole_in_polygon that checks pole point only. With some modification, it might be used for a general case. Again this problem is more complicate on the sphere than on the planar surface

They don’t? I thought your pole inside polygon worked on a sphere. Would it not work in the general case? Any ideas on how to make it general?

Yes, the pole point inside worked on the sphere. Previously we only needed to query the pole point. I will create a new PR for the general case and put my algorithm there.