Hi guys, sorry for the noob question..
but I already change the option in setup for postion 3d, but it doesn't have 3d buildings...

3D buildings only appear when you approach major cities... LA, DC, NYC etc.

http://www.fourtitude.com/news/publish/Features/article_4301.shtml

Also, 3d buildings only show up for the most part when your scale is set to 100 yd or less. Above that they don't show up.