/usr/lib/x86_64-linux-gnu/libvisp_tt.so is in libvisp-tt-dev 3.1.0-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libvisp_tt.so.3.1
/usr/lib/x86_64-linux-gnu/libvisp_tt.so.3.1