To understand the different design document templates better, here is a list of places where you can download and look at templates and examples:
- https://docs.google.com/document/d/1pgMutdDasJb6eN6yK6M95JM8gQ16IKacxxhPXgeL9WY/edit
- https://docs.google.com/document/d/1-I08qX76DgSFyN1ByIGtPuqXh7bVKraHcNIA25tpAzE/edit
- http://robotics.ee.uwa.edu.au/courses/design/examples/example_design.pdf
- https://www.toptal.com/freelance/why-design-documents-matter
- http://portal.unimap.edu.my/portal/page/portal30/BE8D43D77F7A6D38E04400212800D8CE
- https://www.cs.drexel.edu/~dpn52/Therawii/design.pdf
UML is a topic that is discussed in many circles, and there are plenty of resources on it that go into much more depth than I have. The reason for this is that UML could have a book written about it in order to do it proper justice:
- https://www.utdallas.edu/~chung/Fujitsu/UML_2.0/Rumbaugh--UML_2.0_Reference_CD.pdf
- https://courses.cs.washington.edu/courses/cse403/11sp/lectures/lecture08-uml1.pdf
Unity also has some fantastic tutorials where you can learn ARKit with Unity:
These references should give you deeper insight into topics that I lightly touched on.