How to show a .tif file with projected coordinate system in geographic system?

Hello guys, i'm finishing an essay which i need to plot some trajectories points(in lat lon) on a map to do some further analysis. I've now downloaded a .tif file in projected coordinate system. I used

[A,R] = readgeoraster(filename);
mapshow(A,R)

and get the same coordinate system like this example: https://ww2.mathworks.cn/help/map/ref/readgeoraster.html

But what i really need is lat lon corrdinate system. like the image in example 5 here: https://www.mathworks.com/help/map/creating-map-displays-with-data-in-projected-coordinate-reference-system.html

This example 5 requires a .jpg file with geographic data whose coordinates are already in latitude and longitude, which of course i don't have one. I only have the .tfw file along with the .tif file.

So i used the following funtions to extract the lat and lon from the .tif file:

filename = 'G:\SA\Data\dop20c_33412_5654.tif';
[A,R] = readgeoraster(filename);
info = geotiffinfo(filename);
[AY, AX, Z]= size (A);
height = info.Height; 
width = info.Width; 
[rows,cols] = meshgrid(1:height,1:width); 
[x,y] = pix2map(info.RefMatrix, rows, cols);
[lat,lon] = projinv(info, x,y);

And then i get two arrays named lat, lon (10000x10000) with the required latitude and longtitude infomation. But now how can i use these info to plot a new image with these lat and lon?

Or maybe there are other funtions that don't actually need these steps but directly plot the image the way i wanted?

Thank you so much for your help!

[darova]

Is this the picture you want to get?

Do you have color lines?

[Zihan Liu]

no the one with lat and lon is what i want. I don't have any color lines.

This is what i get after using mapshow(A,R):

Answer 1

[darova]

As i understood you correctly: you want to have grid line/dots on your image

Here is an example

A = zeros(100);                         % 2d zero matrix
[X1,X2] = meshgrid(10:20:90, 1:4:99);   % grid
ind1 = sub2ind(size(A),X1(:),X2(:));    % horizontal
ind2 = sub2ind(size(A),X2(:),X1(:));    % vertical
A(ind1) = 1;
A(ind2) = 1;
imshow(A)

[Zihan Liu]

No...This could be helpful, thank you but what i want is to show the image in latitude-longtitude coordinate system, as you can see from my post now it's 5.654x10^6 to 5.656x10^6 as y axis, 4.12x10^5 to 4.14x10^5 as x axis.

[darova]

Use Xtick and Xticklabel

xx = 0:20:100;
set(gca,'xtick',xx)
set(gca,'ytick',xx)
s1 = strsplit(sprintf('%dW\n',xx));
s2 = strsplit(sprintf('%dN\n',xx));
set(gca,'xticklabel',s1)
set(gca,'yticklabel',s2)

[Zihan Liu]

Thanks a lot for your ideas, but i'm sorry it's not directly linked to my problem. It's a relative more complicated case.... I think it requires some funtions from Mapping Toolbox.

Answer 2

[Geraldine Maria Palacios Torres]

Hi Liu

I am facing the same issue. I cannot display the image in its geographical coordinates

I wonder if you figured it out?