I need to place an exterior cave entrance so I ran around the 'preferred' area in the game looking for a location - I found a few. Loaded up the CK and found it increasingly difficult to place a cave entrance with having to move large mountainous sections or without having the entrance going down [the black part] clipping into the ground.

How do you deal with it? Find a better location or completely remake the area with new rocks and mountains? Do you edit the ground as well so you have the depth to place the entrance?

Skyrim's different to Oblivion in that most of the landscape cosmetics are done through statics as opposed to using the landscape tool. So you basically have two options.

• You clear a small area (<1 cell in size) and re-build the area around the new entrance you made. However remember to move and initially disable objects as oppose to deleting them if you can.
  
• You place the entrance into the area, and clear as little as possible. Modify the landscape a tad to make it blend it, rotate things, add rocks and such to cover up any abnormalities. This is my preferred option.

Due to LOD issues, and CTD's on 'deleting' objects, I would find a usable place.
Then:
1. Use landscape editor to dip ground so its not clipping into your cave. Don't manipulate ground too much in viewable areas. Otherwise you will need to redo the LOD which is not fun.
2. Do not delete any rocks. If you must get rid of them, make them 'disabled' in their properties.
3. Place new rocks, but not too many or you will need to redo your LOD.

Anything you do, without new LOD will 'pop' in when the player nears. So when you pick a place, remember that...

Okay. So ultimately I'm going to have to tweak the ground to accommodate the entrance. I'll try to reuse rocks to help obscure things rather than disabling them and make sure not to add too many new items due to LOD - would copying items and using those require a LOD redo? Will disabling a large mountain be the same as if I pushed it below the ground or is disabling better?

LOD was generated as the world looked pre-release when Bethesda were making the game. Anything that was there at the time is in the LOD we have. Think of it as a picture, it's static and doesn't change. So if you add a new huge rock, it won't be visible in LOD, because it wasn't there when the LOD was generated, regardless of it it's brand new or duplicated. Same applies to if you delete or move an existing object, it will stay in its old position in LOD and won't move or disappear until you get within loading distance. Landscape is a little different, LOD for landscape is actually a little bit below ground of the real landscape. If you dip the landscape down too far, the player will actually see the LOD for that landscape, which is obviously bad. However the same applies to that if you make a massive gorge or mountain, it won't be visible and will just pop-up when you get close.

Generating LOD is a pain in the [censored], and modders tend to stay away from it, so therefore it's better to just change as little as possible.

I do the dip the landscape in thing lol, it doesn't take much for those cave entrances. If the player is playing a TES game and can't get over a *tiny bit* of popping stuff to get to the dungeon they want, this is either the first mod they've ever downloaded or it's hopeless to try to appeal to them anyways since they'll be expecting 5x complete remakes of skyrim, kill bill, and the soprano's in your dungeon all at the same time. Even if you deliver they'll come back with comments about how you didn't tune it perfectly to their play style and how the godfather occasionally speaking italian ruined their immersion.

lol didn't mean to rant but that's a funny one. Cover the overlaps with mudcrabs maybe?

Oh that's fine.

What we're talking about is when people decide to flatten mountain ranges and create massive gorges, that not only create huge pop-ins but also reveal the LOD mesh at the bottom of the gorges. Not ideal.

Some great advice. Thanks ere'body!