semless mesh based on voxels in Octree for LOD

Question

Octree to hold voxels lod levels, single Octant has 16x16x16 voxels.

Need to get neighbor voxels for Octant on all 6 faces (neighbor must not have childs) to create correct mesh borders for seamless mesh.

Face can have several neighbors or part of neighbor.

For example:

1. Octant has scale 64, one neighbor has scale 32 -> one Octant side voxel computes from 4(2x2) neighbor voxels,

2. Another neighbor has scale 16 -> one Octant side voxel computes from 16(4x4) voxels.

3. Third neighbor has scale 1 -> One octant side voxel computes from 4096(64*64) voxels.

Octant can have too many neighbours, need to add some restriction.

When neighbor is updated - set "mesh borders out of date" flag

Current bad solution: don't get neighbors, so render all side voxels.

My ideas:

solution 1:
{
    p_neighbours[Face::FACE_COUNT] in Octant
    create Octant neighbours for all childs on creating
    create Octant neighbours when childs are removed
    update meshs_borders flag when neighbour changed

    Octant with childs has invalid Octant neighbours

    problems:
    Octant can have too many neighbours with different scales, or part of neighbour
    hard to code and maintain, too much cases to solve
    Octant still can have too many neighbours
}

solution 2:
{
    don't store neighbour pointers in childs
    instead get neighbour every time by coordinates

    same problems as in prev solution, and new: 
    can't update "mesh borders out of date" flag when creating or removing childs
}

Answer 1

I am found much better solution #3: Octant borders voxels is empty -> one of child's 8 voxels is empty. Neighbors connected only to octant with same scale. If neighbor is missing, border voxels taken from neighbor of parent.