This might happen because the UV is tiled. LODGen re-UVs it to put it on the atlas. That process also tries to optimize vertices/triangles in the end. It's coarse (low precision) and can create such clefts.
See the logs/LODGen_SSE_[worldspace]_log.txt if there are lines about the used texture in the end that look like
landscape\trees\sometrunktexture.dds: 1616 -> 2404 | 788, 0
If that is the case, then possible solutions are:
1) Leave UV and source texture as is, but add a rule to TexGen to create a 2x1 mini atlas trunk texture like treepineforestbarkcomplod.dds (the TexGen rule is defined with 2 lines in DynDOLOD_SSE_TexGen_noalpha_skyrimesm.txt). See DynDOLOD_Mod_Authors.html for more or ask me.
2) Make sure the source model has UV that is strictly between 0 and 1 so no re-UV is required. (Maybe also use TexGen mini atlas texture or create LOD texture manually)
3) Add "NoReUV" to the Name of the BS|NiTriShape in the NIF so the entire shape is left alone. If the UV of the texture is outside of 0 and 1, the texture will be used directly. It maybe be not as good for FPS, but in the grand scheme of things most likely not a big deal because trees in the area using the same shader/texture will still be combined.
Also check https://forum.step-p...ns/#entry229152
If all fails, send me the asset. Maybe I can refine the process.
Edited by sheson, 20 July 2019 - 01:54 AM.