I see what's going on -
The camera you exported the chan file from in Terragen is set to Use horizontal fov in the Perspective tab. If you render out two separate .chan files from Terragen, one with the camera set to Horizontal fov and another set to Vertical fov and open the files in a text editor you'll see all the values are exactly the same. The last value in each row is the fov and it's 42.1034 - which is the vertical fov of the camera. The .chan export from Terragen is a bit screwy in this respect. (It also doesn't export any animated changes in fov - I flagged this with Matt.)
So, if you re-render the Terragen scene with Use vertical fov selected and check it against the Maya render, they will match. Your original micro export geo will be clipped at the sides, as you exported that with the horizontal fov checked - if you re-export with verttical settings, it will fill the frame.
When you open up a new scene in Terragen and check the import tab, you'll see the default is Import vertical FOV, which is how I set the script so you don't have to change any values when importing from Maya to Terragen.
If you check out the edited Terragen scene file, I imported the camera you had set up in Maya back into Terragen via a .chan file, which imports correctly. If you look at the horizontal and vertical fovs for that that camera they're the same (42.10) so all is good.
I personally wouldn't bake directly from the render camera anyway, the geo gets clipped beyond the camera frustum, so you might be missing shadows from something off camera on your CG elements in Maya. Also, from your camera you can only see terrain about 30km away, but the micro exporter was clipping to infinity, so you could actually see the curvature of the planet in the obj file, making a very large file.
I'd set up another camera, make it orthographic and point it straight down over the part of the terrain you want to use.
That's my preferred way of working with the script, I made it so I could make a terrain in Terragen, do an ortho projection and bring it into Maya, then set up the camera with Mayas more extensive toolset for animating cameras, then bring it back into Terragen.
Also if you check your original terrain .obj in Maya - region select a single vertex you'll find 2, 4 or even 8 dupicate vertices. That's why the micro exported terrains are so huge. Maya doesn't really like merging vertices on complex geo like this at all, and forget about trying to clip bits of the mesh off if you want to - takes forever.
I found a free prog called Meshlab which is very good and fast at cleaning up these meshes:
http://meshlab.sourceforge.net/ -
Open it up and drag your mesh into the window and select Filters/Cleaning and Repairing/Remove Duplicated Vertex - check the difference in the vertex count at the bottom of the display. Do the same for faces.
Now you you have a cleaner mesh at about quarter of the size...
Hope this helps.
Edit: Just reading the posts by Jo and Kadri - there is a mismatch in units when importing .obj via the micro exporter into Maya. That's why I wrote the script to automate all that, with the script you can import files from Terragen .obj, World Machine and Geo Control and they will all line up. You can even choose a master scale to work at and any camera animation you create will import back into Terragen in the right place.
