Достать текстуры - фотографируйте свои здания. Документация есть в поставке. см. Using_3D_Analyst.pdf и справку http://webhelp.esri.com/arcgisdesktop/9.1/index.cfm?ID=2305&TopicName=About%203D%20symbology&rand=4&pid=2304
Создавать свои трехмерные символы лучше всего во внешних программах:
You can import OpenFlight (.flt), 3ds max* (.3ds), or VRML
models as 3D symbols. Use this feature if you have existing 3D
models that you’d like to use in 3D Analyst. You can import these
models when symbolizing a feature, or you can import them into
an existing or newly created style.
OpenFlight models can be created using MultiGen–Paradigm
ModelBuilder 3D*. You can use ModelBuilder 3D to quickly
generate 3D models of real-world buildings, objects, and
vegetation for incorporation into an interactive display of 3D GIS.
To create .3ds models, you can work in Discreet 3ds max, or use
@Last Software SketchUp* as a tool for creating 3D models,
then export them to .3ds format.