I need to create a landscape for an environment (playable level) I'm making in UDK. I have used UDK for a good while now and have decent knowledge of its world building workings. Except... I have barely used the landscape editor. At least not at the scale/importance I'm going to need it now.
My first impression is that creating a landscape from scratch just using the brushes etc. will be cumbersome and uneffective, at least in terms of creating satisfying realism. I'm guessing the optimal route is to use something like World Machine or Mudbox to create a heightmap and then adjust it from the landscape editor (?).
So my question is; could you recommend a route of going about this? does it make little difference what I use to form the landscape pre-UDK? Should I go with World Machine? Advantages/Disadvantages?
I have only basic knowledge with 3ds max and zbrush, but I'm not time-restricted in any way so I don't mind taking a while to learn. I'll tutorial/read my way through it once I have a plan. Still, being noob-friendly is always a plus 
In terms of topography I'm aiming for something like this;
[Blocked Image: http://www.dylancolestudio.com/sketches/images/Dcole_Jungle.01.jpg]
NB: the landscape is mostly for visual and thematic purposes. the actual playspace is fairly small.