Adding Lat long Cordinates to a GeoTiff file

Question

I have a Satellite Image of a Terrain, and I have the Latitude and Longitude measures of the four cordinates of the file. How can I add the following data to the GeoTiff file, using Python or Matlab

Answer 1

You can open the file in update-mode and set the geotransform.

It does require your image to be a regular grid, and often the assumption is that it isn't rotated (which you can see if you know all four corner coordinates).

The geotransform also requires the x/y size in pixels, which you can calculate from the image and the corner coordinates if you don't already know these.

If this is more or less where you're starting from:

ulx = -180
uly = 90
lrx = 180
lry = -90

fn = "somefile.tif"

You can calculate and set the geotransform with:

from osgeo import gdal

ds = gdal.OpenEx(fn, gdal.OF_UPDATE)

# calculate the resolution
xres = (lrx - ulx) / ds.RasterXSize
yres = (lry - uly) / ds.RasterYSize

# define the geotransform
gt = (ulx, xres, 0, uly, 0, yres)

# set the geotransform in the metadata
ds.SetGeoTransform(gt)

# close file
ds = None

Since you're modifying an existing file, it would probably be best to first do it on a copy and make sure it's doing what you expect.

If the geotransform is missing, your file might also lack other metadata like the projection. If that's the case you can set it similarly with ds.SetProjection(srs_wkt).