Sim Wide Radar Help!

I'm making basicly a radar they is a small version of a sim with prims respresenting people in the sim.

The problem I'm having is, making the rezzed prims stay on a small enough scale.

I've tried postion / 100

But that stopped the items rezzing with no error.

It's also going to rezz too low, how can I stop that? cause a / will make ground level lower

Any ideas?

You can't rez prims underground. It could be the problem you have.
Add a constant value to the Z-value of the rez coordinates.
See:
http://wiki.secondlife.com/wiki/LlGround
for the ground level.