Need help with selecting certain attributes for raster.

[LaurenRoss1]

Hope someone can help me here!

I am fairly new to Arc GIS so please bare with me.

I have a Landmap 5m DTM and a polygon layer of Dartmoor National Park. The 5m DTM contains data from the South West of
England. I basically want to remove the unwanted data so that it is within or the extent of the Dartmoor National Park polygon.
I know with vector data you can select with attributes but I have no idea how to do this with raster data

Thanks in advance!

[JakeSkinner]

You can use the Clip tool within ArcToolbox > Data Management > Raster.  Choose the polygon as the output extent and check the option 'Use Input Features for Clipping Geometry'.

[LaurenRoss1]

Thank you very much, it worked a treat!