Hi Patrick,
I have found the culprit and probably need to pass it on to Matt to see if this is worth looking at to fix.
To prevent the lines from showing up you need to access a hidden node inside the renderer.
It seemed that the adaptive subdivision algorithm causes the lines, but don't ask why exactly (see link below).
To access the hidden node do the following:
Go to your shader network and click on the "+ symbol" at the right of the rendernode.
You're now inside the internal network of the rendernode, click once on the gray background to make sure you "activate/focus" it.
Copy the code at the bottom of this message and paste it in the internal network of the rendernode. A new grey shader should show up called "render_subdiv_settings 01".
Double-click on it to see the new advanced settings. Everything is default, except that I disabled "fully adaptive".
Here's Matt on these new advanced settings:
http://forums.planetside.co.uk/index.php?topic=9321.msg128311#msg128311Happy TG'ing dude
Cheers,
Martin
<terragen_clip>
<render_subdiv_settings
name = "Render subdiv settings 01"
gui_use_node_pos = "1"
gui_node_pos = "900 -80 0"
gui_group = ""
fully_adaptive = "0"
force_all_edges = "0"
jitter_shading_points = "1"
ray_detail_multiplier = "0.25"
stabilise_ray_detail_in_motion = "0"
ray_detail_stabilisation = "3"
>
</render_subdiv_settings>
</terragen_clip>