Many times when planning for flying in hilly terrain, it can be difficult to find the optimal route for safe flight.
Especially important in view of the low cloud base.
The idea with ClearTerrain is to visualize the desired altitude via a colored polygon exported to an app that presents the polygon in 3D. Google Earth is a very good example, but you can choose other apps that fullfill 3D viewing.
ClearTerrain also makes it possible to test fly a given route.
You simply create a route using the built-in route editor and export route to Google Earth or similar. The result is a realistic flight in the area in which you wish to investigate.
Export GPX data to navigation system such as SkyDemon.