Some updates regarding the auto-retopology subject:
• @Albertofx has released the DynRemesh auto-retopology add-on for Blender. It’s not a custom auto-retopology algorithm, but an automation of several Blender techniques. More info can be found in this Blender Artists discussion.
• A new, improved version of the Instant Meshes auto-retopology algorithm called Quadriflow has been introduced.
Regards,
Metin