Defining collision object accurately in sdf

I'm creating a simple model in Skethcup built of 2 cylinders and a rectangle. Is there a simple way to define the 3 links of the collision objects to tightly couple with the model? I followed this tutorial: [build_model](http://gazebosim.org/tutorials?tut=build_model), but it is too simplistic in the example. More accurately, I've built the model in sketchup and do not know how to extract the cylinders position to be defined as the collision objects since the DAE file contains vertices to defined the geometry.