Change the geospatial data in a geotiff file.

Hello,

my goal is to change the geospatial data of a geotiff file.

In other words, I want to relocate the image to another coodrinates.

More precisely, we have a test-track and I want to bring a piece of a real world road on it.

So when I import the image to the Roadrunner, it shows up where I need it.

How I did it:

1. I read both the image and data separately

data = geotiffinfo(filename);
image = imread(filename);

2. I defined a matrix that I needed to apply to the image

matrix = [0.990950218730870	0.136163909329197	0
           -0.136163909329197	0.990950218730870	0
           741682.197901774	    -43966.3723596139	1];

3. I created a tform object

tform = affine2d(matrix);

4. I created an object that connects the spatial data and pixels.

xWorldLimits = [data.BoundingBox(1, 1) data.BoundingBox(2, 1)];
yWorldLimits = [data.BoundingBox(1, 2) data.BoundingBox(2, 2)];
ref_data = imref2d(size(image), xWorldLimits, yWorldLimits);

5.I applied the matrix to the image and geo-spatial data

[upd_image, upd_data] = imwarp(image, ref_data, tform);

6. Reference object is needed to create a new tiff image.

Rmap = maprefcells(upd_data.XWorldLimits, upd_data.YWorldLimits, size(upd_image), ...
    'ColumnsStartFrom','north', 'RowsStartFrom','west');

7. Finally create a file.

new_filename = ['ra_transformed' '.tif'];
geotiffwrite(new_filename, upd_image, Rmap, 'CoordRefSysCode', 25832);

In the end, it didn't work.

The image is rotated in another direction and moved not precisely.

It's close but not perfectly.

The matrix is correct, I've checked it twice.

Is there anything that I've missed?

Or maybe the overall approach of dividing, changing and gluing it back is wrong?

Answer 1

[Rushan Abdrakhimov]

I have solved the issue.

The problem was in different coordinate orientation in UTM and Matlab.

Just took another sign for angle (for rotation).