I have 235 raster tile 20km x 20km. I need to create a grid to overlay across them...ie the grid itself will be 20km x 20km, with the lines of the grid on the boundaries of the tiles.
I am assuming the vector grid tool is the key as per this question...How to emulate a specific vector grid in QGIS?
However they have created the base map as vector..mine are rasters.
i have search for the tutorial but cannot find it.