Pixel to latitude and longitude cordinates

I created through the m_map package a spatial distribution map of a certain variable, then through the command:

[x y] = m_contour (lon_sla, lat_sla, SSH, [1.15 1.15], 'color', 'y', 'Linewidth', 2);

With this command I obtain a contour line, whose pixel coordinates are stored in the vector x of size 2 * 12389.

How is it possible to convert these pixel coordinates into geographic coordinates lon and lat, in such a way as to preserve the position vector of the contour?

[KSSV]

Your (x,y) should already have the coordinates you want.

[Antonino Ferola]

y is a graphic object and in the vector x the coordinates are referred to the image borders, probably the first row represents the distance of a point from the top border of the image and the second row represents the distance from the left border of the image. I would like to convert this coordinates and store them in a vector where the first column is the long and the second is the lat.

Answer 1

[Udit06]

Hi Antonino,

I understand that you want to obtain the geographic coordinates from the pixel coordinates that you obtained using the "m_contour" command. You can follow the following steps to do the same:

1. Define the transformation function that takes the pixel row and column indices as inputs and returns geographic coordinates as output. The transformation function in this case could be of the form ax+b, where x is the pixel coordinate, a is the scaling factor which corresponds to the region size in degrees and b is a constant.
2. Apply this transformation function to each pixel coordinate.
3. Store the results in a new array.

The suggested tranformation is just an example, you can think of other tranformation functions also.

I hope this helps.