And if you are considering to use 2D polygons and extrude them, you can convert from Shapefile to GeoJson using GDAL easily.
Good point, Iman! If I get this working using ESRI software, I will want to replicate the process using opensource software, and GDAL is a great utility !
Could you please tell me how did you get the 3d models georeferenced, I have the 3d models in collada format but they are not georeferenced. If you know, could you please help me with this.