LOD settings

[Me|eE]

When you create a terrain in UT3 it will LOD at ceatain distances, and while this is a good thing in some instances it has been found that disabling LOD settings in the Terrain will actually make them run faster then to have it enabled. UE3 requires more to calculate the LOD process than it does to render the terrain full quality the entire time. To disable it set both LOD settings to the same number.

I read this tut and just curious if any1 can tell me where the LOD settings are please.
Thank You.

[DGUnreal]

The Terrain LOD is the Tesselation system.

Setting the Terrain.Terrain.MaxTesselationLevel property to any value greater than 1 enables the LOD system. The default is 4. You would use 2, 4, or 8 as common values.
Note that using the LOD requires that your terrain's NumPatchesX,Y be a multiple of the Tesselation value. So you can't use a 255x255 NumPatches with a MaxTesselationLevel of 4.

When you change the MaxTesselationLevel you should also change the MaxComponentSize appropriately, or the terrain may in fact not render faster.

I will have to confirm this, but I believe the proper settings are:

Min,MaxTesselationLevel of 1,1 -> MaxComponentSize of 16
Min,MaxTesselationLevel of 1,2 -> MaxComponentSize of 8
Min,MaxTesselationLevel of 1,4 -> MaxComponentSize of 4
Min,MaxTesselationLevel of 1,8 -> MaxComponentSize of 2

Also, because MaxComponentSize is being changed, if bIsOverridingLightResolution is being used on the terrain, this will also have to be adjusted for the proper lightmap size (StaticLightingResolution).

The tutorial you read is incorrect, it is not faster to disable LOD, ie. to use Min,MaxTesselationLevel values of 1,1.
The tutorial simply must not cover the proper method of implementing the LOD and is in error. An upcoming patch will address this issue and make it more fool-proof and prevent mappers from using the LOD system incorrectly.

[Zoo]

Presuming that your numbers are correct its strange that the default is.

Min,MaxTesselationLevel of 1,4 -> MaxComponentSize of 16

What is the best setting for TesselationDistanceScale ? A lot of the stock maps use 1-2, but WAR-Torlan is 1000 !!!

[DGUnreal]

I just checked the numbers and they should be correct for optimal use in the majority of design cases.
You can also use the TerrainPatches show flag to see the MCS related cube adjustment.

The default MaxComponentSize of 16 isn't necessarily "incorrect", it just may not be optimal for every terrain heightmap design. I would assume the upcoming patch will use the optimal defaults when changing the values. Additional values besides those I cited in my post can be tried to see what performs the best in-game on each specific map. You may see a variance depending on the actual terrain heightmap design itself.

For example, on a large test terrain map here I get:
- MTL4 MCS2 = 27288 tri's 18fps
- MTL4 MCS4 = 41352 tri's 30fps
- MTL4 MCS8 = 75960 tri's 32fps
- MTL4 MCS16 = 148416 tri's 26fps

So my best setting for MTL 4 would be MCS 4 or 8 since they are both very close in fps performance. However, after adding more StaticMeshes and effects to the map the higher triangle count of MCS 8 may offset the overall performance, so 4 would probably be the best choice on the final release map.

Again, if you are using bIsOverridingLightResolution also on the terrain, make sure to adjust the StaticLightingResolution accordingly with the changed MaxComponentSize, or you may create way too many terrain lightmaps and use up a significant amount of memory and have a resulting massive map file size.


The best setting for TesselationDistanceScale should be determined by the actual terrain heightmap design plus what you want to visually see.
Since the Tesselation LOD actually combines terrain patches together starting at the Distance threshold, essentially reducing overall visual detail from that distance outwards from the camera, you usually don't want to push the LOD too close to the camera if the terrain contains a lot of relevant detail. Otherwise you may as well just use a lower resolution terrain.
Personally, if the terrain has any amount of detail in it, the TesselationDistanceScale should be left at the default of 1, and set no higher than 2. The highest I would ever use would be 3. Note that higher values move the starting distance where the tesselation occurs closer to the camera.

I cannot speak for Epic's choice on Torlan, as I was not involved with that, nor have I asked them specifically on that and their design decision.

[Zoo]

I cannot speak for Epic's choice on Torlan, as I was not involved with that, nor have I asked them specifically on that and their design decision.

Torlan Leviathan and Torlan Necris have a setting of 1.5.

The setting of 1000 in the first Torlan might be an error as this map causes strange things to happen for some people like hanging and freezing.

Don't know if this setting could do this?

[DGUnreal]

Setting it to 1000 shouldn't affect whether the map freezes on some systems.
Essentially it will lower the entire terrain to the lowest LOD detail.