You need to set the commander view height in the info_mapinfo entity, which you should have in your map.
Put that entity anywhere in your map, then goto properties and change the "View Height (for commanders)" value from 0 to a better height (z value).
Use your x\z and y\z views to get an idea of where you want the view height to be. It may take a little trial and error, but you'll get there, eventually.
*EDIT: By the way, do NOT do what Naigel suggested. This is because "bad things" could happen and it's a very poor way of approaching the situation. The setting for commander view height is in info_mapinfo for a reason.