I have several jpeg2000 tiles non georeferenced and covering a certain area. I know in qgis you can mosaic image using the merge tool but I have done it only using georeferenced images, which is quite straightforward. I would like to know if there is a method with qgis to mosaic raster images non goreferenced. So basically just stitching tiles above, below, left and right.
This workaround should work:
Create fake world files (.wld or .j2w). Use pixel size 1, -1 and put the origin of your master image into 1,1. Check the size of your images is pixels (width, height) with gdalinfo and calculate origins for the other tiles to match. Remember these:
- origin is at the center of the top-left pixel
- Y (northing) is decreasing from top to down
- putting origin into 0,0 would feel natural but in some cases it can make GDAL to do odd things and using 1,1 instead is more safe
The complete world file for tile1 would be
1.0 0 0 -1.0 1.0 1.0
Another option is to create a .vrt file from all the images with gdalbuildvrt utility and edit the resulting .vrt file http://www.gdal.org/gdal_vrttut.html which is a XML text file. element has roughly the same information as a world file.