collision issues

my name is mauro, me and some friend are working on a 3D RPG as a graduation project. We were using panda3D so far, but we’re having some problems with the collision.
The game is a 3rd Person one, so we need to have our main character to walk over the scenario and collide with it. We tried to make a collision sphere around him and “turn on” the geometry collision, but it seens tha the character is also a geometry, so the sphere collides with him, and the chaos began to show its face.
How can I make my character to collide with all other models/enviroment ?

By the way, does anybody have any idea how many polygons have on the Panda Model (the one we use on the tutorial)?

Thanks a lot