Topo
Topo is a terrain analysis package designed to support water management
decisions and to generate instruction sets for machine control in field
leveling and flossing operations. It has synergies with
AGIS in that the basic file formats are interchangeable.
People who use Topo at a high level to adress water management issues are PCT in Australia.
The commercial model is a subscription. Subscription terms may be reviewed here. AGIS Topo Subscription
Here is a link to a sketch of Topo concepts.
Download Topo for Windows XP
Download Topo for Windows 7