I have a model that is made of a flat plane that has been sculpted in the middle. I need to fade the edges of the plane gradually into transparency. How do I accomplish this? I am totally new to this! Thank you for help!
Response to Cegaton:
Thank you, this works just as described on a new plane. It is really just what i need, but it does not work on my model, which was modeled in Blender 2.7, if that makes any difference. On my model, the adjustment only affects the top half of the mesh, and the bottom part is either translucent or opaque, with sharp edges. I am baffled. I will add that the model was made from a plane but many nips and tucks and extra rows of vertices have been added since the beginning. I wonder if there is something about an older model that does not work with the new compositing options ('separate xyz' was not available in 2.7).
PROBLEM SOLVED: The transparency begins at model's origin. I moved the origin point from the center to the bottom of the model and now the transparency adjustment is operating exactly as demonstrated in Cegaton's answer.