hierarchy sprites scene frame layer bones semant Organiza hierarchy

 https://www.researchgate.net/figure/Human-skeleton-and-the-corresponding-hierarchical-structure_fig3_328011229

https://www.researchgate.net/figure/Logical-structure-of-the-scene-courtesy-of-MPEG-Systems-Group_fig10_3307965 

https://docs.cocos.com/creator/manual/en/asset/sprite-frame.html

sprite  scene frame layer semantic