how can I calculate a grid on top of a raster layer

[MiguelGomez]

Hi all,

I have a raster data of elevation terrain for the 50 provinces of Spain. I did a mosaic in order to get a single raster of elevation data for the whole country. Now I need to superimpose a grid of 90x90 meters that will allow me to calcutale a ruggedness terrain index.

Can anybody suggest which might be the best way to acomplish it?

thanks

[DanLee]

If you want a vector grid, have a look of the Create Fishnet tool:
http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//00170000002q000000