7

Some councils have 3D models of the buildings which they're considering sharing. What would be a good format to encourage them to use, if possible? I had thought 3DS would be the standard, but according to Wikipedia, the shortcomings are pretty limiting.

  • All meshes must be made of triangles.
  • All texture filenames are limited to the 8.3 DOS format.
  • The number of vertices and polygons per mesh is limited to 65536.
  • Accurate vertex normals cannot be stored in the .3ds file. Instead "smoothing groups" are used so that the receiving program can recreate a (hopefully good) representation of the vertex normals. This is still a hold-over legacy for many animation programs today which started in the 1980s (3DS MAX, Lightwave and trueSpace still use smoothing groups, and Maya did up to v2.51).
  • Object, light and camera names are limited to 10 characters. Material names are limited to 16 characters.
  • Directional light sources are not supported.
  • check out visicities; its a platform, not a format, but maybe what they are using is best – albert Apr 16 '15 at 15:28
  • 1
    AFAIK, vizicities is 2.5D, not 3D - it just uses building outlines and heights to project upwards. No support for texturing or anything like that. – Steve Bennett Apr 17 '15 at 0:07
  • ah, my bad. i've never used it – albert Apr 17 '15 at 0:50
  • 1
    I'm Robin, the guy behind ViziCities. While it's true that one of the example outputs is a 3D extrusion of 2D shapes (so 2.5D, ish), this only applies to buildings that are is this format (eg. OpenStreetMap). The platform is fully 3D and already supports complex 3D buildings with textures via formats like collada and OBJ. – Robin Hawkes Apr 17 '15 at 8:58
5

In answer to the original question, you should look at CityGML – this is a standardised format that's being heavily used by cities, particularly in Europe. It handles model definition, textures, various feature types (buildings, bridges, street furniture, all sorts) and has been built to keep the data about buildings and other objects intact (eg. which part is the roof and which is the wall). In fact it has various levels of detail that can be used depending on your need, so you could even go as far as modelling the full interior of a building down to the fixtures and fittings.

Here's an example CityGML building at LOD2 (not the worst, not the best):

enter image description here

That building is actually within a new open building library that I'm creating with the guys at Mapzen that uses ViziCities (I'm the creator of ViziCities). We hope to release it publicly very soon.

Failing that – collada or OBJ or fairly well used by cities for sharing buildings.

  • Thanks very much - that's really interesting. Definitely investigating. The semantic richness cuts both ways. Great to have data that knows what a wall is vs a roof etc, but not necessarily easy to generate that data... – Steve Bennett May 2 '15 at 12:52

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.