# Find 2D intersection in lat lon between curve (rivers) and satellite traces (2D polygon) on a map

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Hello, this is an expanded question to the original 1D problem in https://es.mathworks.com/matlabcentral/answers/1740820-find-curve-intersection-points-in-lat-lon-between-rivers-and-satellite-traces-on-a-map

I have a set of (lon,lat) points defining the course of a river. Then I also have a set of (lon, lat) points defining the traces of satellite measurements on-ground. The trace is not 1D, there is a 'left' point and a 'right' point, denoting what woud be in reality a continuous 2D band. In fact both the river and the trace are continuous. I want to find the intersections between the river (a curve) and also the 2D trace. I managed in 1D with the answer of the link above, but not evident in 2D at all. Thank you

PS: I include now included exemplary mat data, with the [lon lat] values of the river, and the [lon lat] values of the satellite trace, defined by the left and right points that define the band/belt extremes. On of the problems I see as well is that close to the poles the bands mix because of the projection effect...

### Answers (1)

Bjorn Gustavsson
on 17 Jun 2022

If you have a single-pass of the satellite you could check what "river-points" are inside the ground-track with the inpolygon function. Check the help and documentation for illustrating examples. My approach would be to split up the satellite-track into single-pass-segments and search for points inside the ground-track pass-by-pass and collect what I need from each.

HTH

##### 4 Comments

Bjorn Gustavsson
on 17 Jun 2022

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