`pathcrossingps71`

`pathcrossingsps71` is part of Antarctic Mapping Tools for Matlab (Greene et al., 2017). Click here for a complete list of functions in AMT.

`pathcrossingsps71` returns crossing point(s) of two paths in or around Antarctica. Calculation is performed by converting input lat/lon arrays to polarstereo (-71) x,y coordinates, finding intersections, and then converting intersection point(s) back to georeferenced coordinates.

Before using this function, check to see whether `crossovers` might better suit your needs. They do similar things, but `crossovers` finds all self intersections of within a single dataset, wherease `pathcrossingsps71` finds the intersection point(s) of two distinct datasets.

## Contents

## Syntax

[lati,loni] = pathcrossingps71(lat1,lon1,lat2,lon2) [lati,loni] = pathcrossingps71(lat1,lon1,lat2,lon2,ClipOption)

## Description

`[lati,loni] = pathcrossingps71(lat1,lon1,lat2,lon2)` returns lat/lon pair(s) for intersection of paths given by lat1,lon1 and lat2,lon2.

`[lati,loni] = pathcrossingps71(lat1,lon1,lat2,lon2,ClipOption)` allows turning off of automatic data clipping for large data sets. Use the string `'noclip'` to turn off clipping. Clipping is on by default because calculating the intersection(s) of a million-point flight line with another multi-million point flight line would be very slow.

## Example: Intersection of snowmobile track with grounding line

Here we'll grab (very approximate) grounding line data from Mouginot et al and see where it intersects a snowmobile track given by four waypoints:

```
[glat,glon] = antbounds_data('gl');
tracklat = [-75.4491 -75.4657 -75.3771 -75.1145];
tracklon = [-94.4371 -95.4879 -97.8617 -101.0862];
```

For context, let's plot these data:

% Initialize a 350 km map centererd on PIG: mapzoomps('pine island glacier','mapwidth',350,'inset','northeast') % Plot a MOA image: modismoaps % Plot Mouginot's grounding line: antbounds('gl','color','green','linewidth',2) % Plot the track: plotps(tracklat,tracklon,'ro-','linewidth',2)

Now find the intersection and plot it as a big blue star:

[intersectlat,intersectlon] = pathcrossingps71(glat,glon,tracklat,tracklon); plotps(intersectlat,intersectlon,'bp','markersize',20,'markerfacecolor','blue')

## Citing AMT

If this function or any other part of Antarctic Mapping Tools is useful for you, please cite the paper that describes AMT.

Greene, C. A., Gwyther, D. E., & Blankenship, D. D. Antarctic Mapping Tools for Matlab. *Computers & Geosciences*. 104 (2017) pp.151-157. doi:10.1016/j.cageo.2016.08.003.

## Author Info

Chad A. Greene of the University of Texas at Austin's Intitute for Geophysics (UTIG). August 2014. This function includes the InterX by NS.