Translating (reposition) TIFF raster layer in QGIS

Question

I'm starting to use QGIS for my thesis (environmental physics) and have to admit I'm pretty ignorant about it - I've always used Mathematica or Matlab.

My problem is: I have a raster layer, in .tif format, which is misplaced (I need to move it south and west by 100m). I need to translate (reposition) it, and I have absolutely no idea on how I can do that.

I've tried Affine transform but it doesn't work (doesn't let me select an input layer); I've also read this How to translate (reposition) a raster in Python? but I have to admit I haven't understood much of it, I tried several times but am no good with python.

Answer 1

ah! I managed to do it, following what's been said in the linked discussion.... (How to translate (reposition) a raster in Python?) apparently it just took me a while to figure how to use the python console! ;) thanks anyways! :)

I used GDAL/Python, from the QGIS Python console! :)

what I wrote was:

from osgeo import gdal
gdal.AllRegister()
rast_src = gdal.Open('filename.tif', 1 )
gt = rast_src.GetGeoTransform()
gtl = list(gt)
gtl[0] -= 200
gtl[3] -= 100
rast_src.SetGeoTransform(tuple(gtl))
rast_src = None

EDIT: switched "gdall.AllRegister()" to "gdal.AllRegister()".

Answer 2

The Rasmover plugin should do what you want.

You have to allow for experimental plugins to get it in the plugin list.

The result is a virtual raster file, which you can edit with a text editor to adjust the parameters if needed.

Answer 3

In the special case where the raster already has a UTM projection, and you want to move it longitudinally to another UTM zone, I found that gdal_translate can do it. For example, the input raster is in any UTM zone Z, and you want to move it to UTM zone 26 (i.e., the Atlantic Ocean at most latitudes):

gdal_translate -a_srs '+proj=utm +zone=26 +datum=WGS84' input.tif output.tif

The origin and corner coordinates in model space units as reported by gdalinfo remain the same. But the corner coordinates in latitude/longitude change, and the raster really did move to another part of the world.

Answer 4

Here is an example on how you do that with rasterio Reference: An issue I opened and dissuaded a while ago.

• Example 1: read, reposition/shift, and write in a new tif file

import rastrio
# specify the needed x and y for the reposition/shift
x = -7.247 
y = 35.08
with rasterio.open('./orbview_data/orbview_3.tif', 'r') as data:
    img = data.read()`
        
    with rasterio.open('./orbview_data/orbview_3_shift', 'w',
                       driver='GTiff',
                       height=data.shape[0], width=data.shape[1],
                       count=data.count,
                       dtype='uint16',
                       crs=data.crs,
                       transform=Affine.translation(-7.247, 35.08) * data.transform) as dst:
        dst.write(img)

• Example 2: read, reposition/shift, and update in the same tif file

import rasterio
with rasterio.open("./orbview_data/orbview_3.tif", mode="r+") as dataset:
    dataset.transform = Affine.translation(-7.247, 35.08) * dataset.transform

Answer 5

In QGIS

If you want to do this in QGIS, the "Freehand raster georeferencer" might work. You can add it via "Plugins -> Manage and Install Plugins...". It allows you to move rasters around, using the mouse. It did work for me for some GeoTiffs, but failed to open others.

From command line

The other option is to use GDAL functions from the command line. You need to have GDAL with OSGEO installed on your computer for this to work. You can move a GeoTiff by setting (overwriting) new upper left and lower right coordinates of your geotiff using gdal_edit.py -a_ullr. I recommend you make a backup of your GeoTiff before you start, as the command diretly modifies the file.
If you do not know the current coordinates of the corners of your geotiff, run gdalinfo your_map.tiff and look for the "Upper Left" and "Lower Right" cordinates (first pair of numbers, which are in metres, if you geotiff's LENGTHUNIT is metre). Keep a note of those numbers, and add however much you want to move your raster towards east (subtract 100 to shift 100m westward) to the first number of both corners and do the same for shifting north with the second number of both corners. Then call gdal_edit.py -a_ullr new_ulx new_uly new_lrx new_lry your_map.tiff.
Import the GeoTiff into QGIS again and you should see it in its new place.