I have a 3D model of a city, divided into ~7000 adjacent tiles, taking up close to 100 GB in total, including fbx files and textures.
I want to convert this into a model with different levels of detail, so that an apropriate level of detail can be choosed dynamically at runtime wheen zooming in to or out from the city. The framework that is used to render the city is OpenSceneGraph, so the model should preferably be in osgb format.
How do I do this the easiest way? I don't have access to any commersial 3D software such as Maya or 3ds Max.