Demo https://output.jsbin.com/votuvi and http://learnwebvr.xyz/upload/PGMarch2017/assets/Pampers/ or even http://learnwebvr.xyz/upload/testing/
Exercise : clone that demo hide that little personage in a forest of tree, make it as realistic as possible.
Extra exercise : what's missing to make that scene much more realistic beside a nice smell of pine trees and glacial temperatures?
Done? Go back to learn more.