/usr/lib/x86_64-linux-gnu/libosgViewer.so is in libopenscenegraph-dev 3.2.1-6.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libosgViewer.so.100
/usr/lib/x86_64-linux-gnu/libosgViewer.so.100