Question: Why does it take me sooo long to render just an alpha pass of a scene in Vue?
I have a scene that I am compositing together with Lightwave and I need alpha channels for it. Problem is the renders take really long, so what I did was hide the objects from render that are from lightwave (2million polys). And so when the Vue colour renders are complete, I run a pass with really low settings, basically only apply materials check in User settings for rendering, But I unhide the imported model from lightwave, put it in a layer with other objects that Lightwave will need composite and render out a "multipass" render of the alpha channel of the layer. But I have found I cannot render just the alpha pass in Vue, so it still take a considerable amount of time to render out a alpha pass for compositing.
Does anyone out there know a way I can speed things up? is there a hidden alpha only render mode somewhere that I have missed?
Thanks a heap