How to read the X,Y and Z coordinates from a TIFF image extracted into Matlab?

I have extracted a TIFF image into Matlab using the geotiff function [A, R] = geotiffread(filename). Now the image is stored for example in A. I want to extract the X,Y and Z coordinates from this image and plot it later using surf function. How do I achieve this?

Thanks for any inputs or pointers

Answer 1

[Chad Greene]

Here are the x and y coordinates of a geotiff:

I = geotiffinfo(filename); 
[x,y]=pixcenters(I);

2022 Update - The function pixcenters will be removed in a future release. Use the worldGrid functions instead.

[Sachin Nag]

Hi, Thanks for the answer. But I also have to plot the height function which is stored in Z. How do I extract the height information so that I can use it in surf like surf(x,y,z).

[Chad Greene]

What information is in each pixel of your geotiff? Is it height? If so,

z = geotiffread(filename); 
I = geotiffinfo(filename); 
[x,y]=pixcenters(I);

Otherwise, you'll have to get z from somewhere else, like a geoid or whatever height you're using.

[Sachin Nag]

Yes, exactly. In the geotiff image is the height information as well. After extracting the x,y and z do you know how to plot it like a 3D plot which shows a conical projection corresponding to the height present in the geotiffimage (for example height of a tree in the image). I used this function to plot.

surfc(x,y,z);
axis tight;

But all I'm getting is a blank plot like the one shown in the image I've uploaded. The point where the tree is present must be shown as a height and not a contour. Thanks for any Information

[Sachin Nag]

I was able to get the correct plot after changing the Matlab version! Thanks again for your help and time

[Chad Greene]

Excellent, glad I could help!

[dd]

Hi Chad,

Would you know how to replace the 'pixcenters' function to get the x and y coordinates of a georeferenced image?

I used to call this function in 'geoimread', but calling the 'worldGrid' that you advised here does not work.

Best, Dd

Answer 2

[sajeela khan]

hello sir can u plz send me the code that hp ow u find the x y and z axis of an image