@article{HildebrandtTimm2014,
  author    = {Dieter Hildebrandt and Robert Timm},
  title     = {An assisting, constrained 3D navigation technique for multiscale virtual 3D city models},
  journal   = {Geoinformatica : an international journal on advances of computer science for geographic information systems},
  volume    = {18},
  number    = {3},
  pages     = {537 -- 567},
  doi       = {10.1007/s10707-013-0189-8},
  year      = {2014},
}