Determining whether a point on earth (given latitude and longitude) is on land or ocean

Question

Soumyadeep Chatterjee 2011-2-9

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回答： Joshua Carmichael 2023-10-4

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

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Walter Roberson 2011-2-9

Where do you place the dividing line for estuaries ? Or for reclaimed land?

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Answer 1

Amy Haskins 2015-4-1

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编辑：Amy Haskins 2015-4-1

在 MATLAB Online 中打开

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);

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Answer 2

Brett Shoelson 2011-2-9

2
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在 MATLAB Online 中打开

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