Quote: "Did you use T.ED?"
I used T.ED for the particular model demonstrated. I spent a bunch of time making terrain models from heightmaps but the process didn't produce an end result which is predictable enough.
The only way to produce a large terrain model with complete control and precision is to build it up from a plane.
Quote: "the poly count is about 8000 polygons.But i will try to make it lower so it can render faster and put some better textures on it si it can still look good."
Your current model does look a little high poly for FPSC X9 at the moment but that may change with planned performance improvements to the engine / mods etc.
Quote: "About the enemy collision...any idea how can that be solved?If not i'll figure something out"
After solving the player collision detection issues with large terrains in FPSC and eradicating lag spots, I couldn't find a way to prevent enemies falling through the terrain.
It has been suggested to use invisible floor segments underneath the terrain surface which would only work well for flat sections of terrain.
Enemy collisions are only predictable with segments which is why Rolfy made a segment based solution which works but limits you to the size and complexity of the terrain.
Quote: "i was thinking to make some low poly trees for the areas where the player will go and use bilboard ones in the back.Will tat kill the framerate too much?"
Stick with billboards. They look fine up close providing the texture is good / hi resolution. I'm afraid this will just be trial and error once you've got your terrain in FPSC.
You'll also have fun placing entities as the FPSC map editor doesn't seem to have been designed with a single model the size of the editor in mind. Therefore make sure you export the mesh with the point of origin in the centre, not the corner. It's perfectly possible though.
I'm going to try higher poly count terrains in FPSC X10 to see how they perform and if it makes a difference for enemy collision.
Keep going with this, only a handful of us have put any real effort into making terrains in FPSC possible but I still believe its a goal worth investment of your time.