Creating vector grid using QGIS?

Question

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.

Answer 1

This is quite simple you can use gdaltindex to build this grid.
In QGIS go to Raster -> Misc. -> Tile index. Give the path to the raster-files, set the name and directory for the resulting shape. I prefer absolute paths for catalogue purposes.
Then hit ok. :)