light probe (for global illumination) placement techniques?
Looking for answer for similar question, I found that work: http://www.cse.chalmers.se/~uffe/xjobb/bowald_final_master_thesis_v2.pdf

It is based on automatic grid placement which depends on scene voxelization. Inspired by this I developed similar technique:


First scene is voxelized with small voxel size (binary voxelization for memory saving)
Result is downsampled to desired grid size (size of each cube with eight probes on each corner)
Based on result - data structures are prepared
Empty areas are optionally computed - cubes size can be bigger to save memory of volumes and probes buffers but it must be always multiplication of smallest cube size to fit in the grid
Lighting for each probe is precomputed


Data structures are:


Volume map buffer - mapping world position to volume index
Volumes buffer - each is array of eight probe indices
Probes buffer - SH data of each probe


This way performance is constant, fast and independent of quality (size of cube) unlike in tetrahedra grid searching algorithm.

However I don't know if there is more recent advancement in that field. You might check http://jcgt.org if there are any new research papers.