2015-08-02 Notes of multi-level instancing "Massive Model Visualization using Real-time Ray Tracing" SIGGRAPH 2007 https://graphics.cg.uni-saarland.de/fileadmin/cguds/papers/2007/MMV/MMV_Dietrich_SIGGRAPH2007.pdf "Terrain Guided Multi-Level Instancing of Highly Complex Plant Populations" https://graphics.cg.uni-saarland.de/fileadmin/cguds/papers/2006/dietrich_06_MLI/Dietrich_et_al._-_Terrain_Guided_Multi-Level_Instancing_of_Highly_Complex_Plant_Populations.pdf Embree API https://embree.github.io/api.html