High production costs for the construction of 3D
models from available data such as technical drawings, maps, images, 3D
scans.
Heavy loads in data storage, since massive amounts
of memory are needed in order to store complex structures together with
textures at non trivial resolution.
Sophisticated visualisation, since interactive
rendering of complex 3D models accounting for illumination and other
aspects necessary in order to reach spectacular photo-realism is only
possible on large workstations equipped with costly graphics-oriented
hardware.