Dear Matlab community, I am given the number of pixels as 768 by 768 for a TIFF image and I am required to convert it to x and y geographical coordinates

Question

Rukundo Wellen 2022-12-26

回答： Nadia Shaik 2023-3-10

I have treid all the referenced past examples but none works with my case.

Voss 2022-12-26

Please upload (using the button with the paperclip icon on it) your image and the code you have tried so far.

Rukundo Wellen 2022-12-27

I = imread('xp.tiff');

info = imfinfo('xp.tiff');

height = info.Height; % image height in pixels

width = info.Width; % image width in pixels

[H,W] = meshgrid(1:height,1:width);

R = georefcells([-90 90],[0 360],2,2,'ColumnsStartFrom','north')

[x,y] = pix2map(info.R, H, W); % the pixel coordiantes are transfeered to the intirinsic coordiantes

[lat,lon] = projinv(info,x,y); %to transfer intirinsic to geographical coordiantes.

Answer 1

Nadia Shaik 2023-3-10

Hi Rukundo,

I understand that you wish to convert the pixel coordinates to geographic coordinates. Below are a few changes you can consider:

when you use "meshgrid", the first input should be the width (i.e., the number of columns) and the second input should be the height (i.e., the number of rows):

[W, H] = meshgrid(1:width, 1:height);

You can use the "geotiffread" function instead of "imread" to read in the "TIFF" file. This will give you both the image data (I) and the R structure, which contains the georeferencing information.

[I, R] = geotiffread('xp.tiff');

Hope this helps!