I’ve not done this before but I think this is an interesting PhD topic for someone and of course there is a 3D city angle!
University College London and the Ordnance Survey are currently inviting applications for a 3-year PhD studentship in “Creating Dynamic3D City Models for Smarter Cities” which will examine the creation of multiple 3D models from a single data source (through generalisation/abstraction). The PhD will be supervised by Dr Claire Ellul (UCL) and by Jeremy Morley (Ordnance Survey). The closing date is the 28th July.
You can find more details here: https://www.findaphd.com/search/ProjectDetails.aspx?PJID=76840&LID=985
Anyone interested is welcome to contact Claire Ellul on firstname.lastname@example.org for an informal chat.