Radial Fade won’t work because it would turn the result into a series of dots. What you need is to use an alpha that is white in the center and fades to black at the top and bottom. When putting this tutorial together, I created one on the fly simply by using a 512x512 canvas and the Cylinder3D tool.
Here it is for you.
[[attach=21531]DirectionalFade.jpg[/attach]](javascript:zb_insimg(‘21531’,‘DirectionalFade.jpg’,1,0))
Remember that you can control the amount of fade on the fly using the Alpha Adjust curve.