Well, you can always edit the "0.0025" constant in the shader to something else, like 0.0015. It'll be sharper, but you get some slightly jagged edges at some places.
I do not believe that there is actually someone here that used Imagine 2.0 on Amiga.. Glad to know that I am not here alone...
Btw, I do not know how many people actually appreciate what the current 3d accelerators do right now.. I mean I remember to wait about an hour for a simple scene to render using this rendering program which can be easily done in real time now...
I did play around with Imagine on my Amiga once upon a time, but I can't remember which version that was... My father got VideoScape3D and Modeller3D instead (by good old Allen Hastings IIRC) which was quite a bit faster; but didn't do real ray-tracing.