View Full Version : IBK tips?
January 4th, 2007, 10:53 AM
Does anyone have any handy tips when it comes to pulling a key using nuke's IBK? The documentation that comes with nuke is very vague on this topic.
When I pull my key I usually look at the alpha while pushing around the lights and darks in the IBKSFill node, then hop over to the IBKGizmo node and do the same thing. It seems to be getting the job done, but I was wondering if there was a better way of doing this.
If you know of any online tutorials using the IBK, I'd love to know.
January 7th, 2007, 03:43 PM
If the backing is a bluescreen then the first thing I do is bring down the darks->b while viewing the ibkgizmo's alpha output (with default ibkgizmo settings). Once I see an intensity change in the garbage area of the matte then I know that i have gone too far and just back off a bit. Next I start to bring down the lights->b and repeat the same process. What this does is remove the dark and light blue squares you see with a default ibksfill and gizmo setup while keeping the original bluescreen colours. Occasionally you will see red or green squares which can be eliminated with the other darks and lights channels. When dealing with a greenscreen then adjust darks->green and lights->green in the same manner. The sfill node is tuned for blue/green screens and assumes that (r+g)<b (for bluescreens) in the screen area. If the default output is black (usually when trying to pull a key on a sky plate) then simply lift the lights->blue until the characteristic blue squares reappear.
Next, the separation controls deal with the hardness of the matte. If you have a saturated red foreground element which has a dark edge bring down separation->r. Same idea for green. Fixing the edge of one area will undoubtedly make other areas more transparent- use ibksplit with soft bezier mattes to have various ibkgizmos with different separations.
January 9th, 2007, 04:52 PM
hey, thanks for the tip... It's working like a charm!