extracting lat/lon from tif file using matlab

Question

Seyedeh Fardis 2023-10-24

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2038056-extracting-lat-lon-from-tif-file-using-matlab

评论： Cris LaPierre 2023-10-25

I have a tif file with a map of locations that has data. I want the lat/lon of that locations using matlab.

I ploted that in matlab using this code

[tifImage, R] = geotiffread('NA_CONUS_border.tif');

>> tifImageDouble = double(tifImage);

>> figure;

mapshow(tifImageDouble, R);

title('Georeferenced TIFF Image');

locations with data has [R,G,B]=[1 1 1].

I want to Convert pixel coordinates to geographic coordinates [lat lon].

does anyone have any idea how to do that?

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Dyuman Joshi 2023-10-24

@Seyedeh Fardis Please attach the tif file (as asked earlier as well).

And mention which version of MATLAB you are using.

Seyedeh Fardis 2023-10-24

NA_CONUS_border.tif.zip

I'm using R2020a .

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Answer 1

Cris LaPierre 2023-10-24

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2038056-extracting-lat-lon-from-tif-file-using-matlab#answer_1339831

编辑：Cris LaPierre 2023-10-24

在 MATLAB Online 中打开

NA_CONUS_border.tif.zip

See this answer, which was updated in 2022.

https://www.mathworks.com/matlabcentral/answers/8865-geotiffread-getting-latlon-info

I will mention that I did have to set the 'OutputType' to get it to work.

unzip("NA_CONUS_border.tif")

% Read image file using readgeoraster

fname = "NA_CONUS_border.tif";

[A,R] = readgeoraster(fname,"OutputType","double");

mapshow(A,R)

% Create grid of X,Y values

[x,y] = worldGrid(R);

% Convert grid of X,Y values to latitude/longitude

[lat,lon] = projinv(R.ProjectedCRS,x,y);

% Extract lat/lon locations of white line

NA_lat = lat(A==1);

NA_lon = lon(A==1);

% Plot extracted latitude/longitude on geographic axes

figure

geoscatter(NA_lat,NA_lon,'.')

geobasemap satellite

title("geographic axes")

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Seyedeh Fardis 2023-10-25

Thank you for that! does tif file contain data as well? I have a dataset and I want to see which data is for which node. I'm not sure if that data is available is tif file as well. if yes, how I can load then in matlab in ordeer of lat/lon?

Cris LaPierre 2023-10-25

You could check what information is available using geotiffinfo

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Answer 2

DGM 2023-10-24

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2038056-extracting-lat-lon-from-tif-file-using-matlab#answer_1339836

在 MATLAB Online 中打开

I never really use mapping stuff, so take this with a grain of salt.

fname = 'NA_CONUS_border.tif';
[tifImage, R] = geotiffread(fname);
S = geotiffinfo(fname);
tifImage = double(tifImage); % contains unique values [0 1 2] (a label array??)
mapshow(tifImage, R);
title('Georeferenced TIFF Image');
% get pixels that are exactly 1
% this ignores the fact that pixels >1 will also be white.
% adjust the test accordingly
[row col] = find(tifImage == 1);
% convert to lat/lon
[x y] = pix2map(S.RefMatrix,row,col);
[lat lon] = projinv(S,x,y);

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Seyedeh Fardis 2023-10-25

Thank you for that! does tif file contain data as well? I have a dataset and I want to see which data is for which node. I'm not sure if that data is available is tif file as well. if yes, how I can load then in matlab in ordeer of lat/lon?

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