Occlusion Planes vs Roombound+portal, how are they different, which should i use?

[Legacy1231]

From my understanding, both of those do the same thing, de-render stuff for optimization. With Occlusion Planes, it is more flexible as you just need to place it in between wall and ceiling, for roombound, you will have to connect it together using portal.

That being said, i suspecting that there are pros and cons for each of them, which i dont know, even the wiki didnt give much information, so i would really appreciated if any veteran modder could shed some light for me

[Nico coiN]

The roombound+portal system is the "default" optimization mechanism for interiors. It's really effective & reliable but has to be built at the same time as you are building the environment, just to make sure that your roombounds and portals 100% fit/match your designed "visual" architecture. You have to deal with constraints: you have to build some kind of "tortuous" environment in order to break long sight views which would result in visual rendering oddities. It can be a headache to setup in very sophisticated multi floor dungeons (Kolbjorn barrow for example) and the vanilla game has many flaws of this kind, while most are fixed by USSEP. As roombounds size seem to have some kind of limitation, its use is limited to interiors with "not too wide" rooms.

Occlusion planes may look easier to handle (true) but are mostly used in exteriors, where you have very long ranges of view and where a LOD rendering system deals with optimization past a specific distance from your character. They are, for example, heavily used in Open Cities and various exterior optimization mods such as the eFPS series. It can cause visual oddities when several mods modify the same area.

These are just a few specificities I experienced myself and may help your future design choices, but you may ask the question to Sheson (DynDOLOD mod) and other large worldspaces authors (Jonx0r/Wyrmstooth for example).