Determining whether a point on earth (given latitude and longitude) is on land or ocean
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I am looking for a quick way to determine whether a point on earth's surface (given latitude and longitude) falls on one of the continents or on an ocean.
Any help is greatly appreciated.
Thanks, Deep
1 个评论
Walter Roberson
2011-2-9
Where do you place the dividing line for estuaries ? Or for reclaimed land?
回答（6 个）
Amy Haskins
2015-4-1
编辑：Amy Haskins
2015-4-1
You could also try the inpolygon function.
% Load the coastline
coast = load('coast.mat');
ax = worldmap('world');
geoshow(coast)
% Grab a point from the map
[lat,lon] = inputm(1,ax);
% Determine if it's within the coast polygon
isInland = inpolygon(lat,lon,coast.lat,coast.long);
Brett Shoelson
2011-2-9
I think this will do it. It is a binary classifier: Ocean/Land.
coast = load('coast.mat');
[Z, R] = vec2mtx(coast.lat, coast.long, ...
1, [-90 90], [-90 270], 'filled');
figure; worldmap(Z, R)
geoshow(Z, R, 'DisplayType', 'texturemap')
colormap([0 1 0;0 0 0;0 1 0;0 0 1])
lat = 38.53;%N
lon = -57.07;%W
plotm(lat,lon,'ro')
val = ltln2val(Z, R, lat, lon);
isOcean = val == 2
%isLand = ~isOcean
Cheers,
Brett
1 个评论
Dan Chavas
2014-2-11
I've put this code into a MATLAB file: http://www.mathworks.com/matlabcentral/fileexchange/45268-landorocean-m
John
2011-2-9
0 个投票
Perhaps something like this could help:
Chad Greene
2015-1-28
0 个投票
landmask(lat,lon) returns 1 for land, 0 for ocean.
Joshua Carmichael
2023-10-4
0 个投票
The Matlatb function isinterior.m (new since 2022a) does this.
There is an even simpler solution, similar to Amy Haskins above, that does not even require the use of geo data.
I'm working with digital data. The satellite scans a patch of the Earth and sends back the lat and lon coordinates of each sample point in a 571 x 318 array.
I wanted to use the isinterior() function to tell if a point is inside or outside the shoreline, but it doesn't work with geopolyshape data. I realized that you don't need to use geo objects for this, just a simple axis object.
gx = axes;
load coastlines;
coast = polyshape(coastlon, coastlat)
plot(gx, coast);
Then as you cycle through each satellite lat/lon array, you call isinterior:
idxLand = isinterior(coast,lon,lat);
landlon = lon(idxLand);
landlat = lat(idxLand);
This will clip all the data outside the continents. It works like a charm, without resorting to geo data.
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2011-2-9
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