More on Channels

When I start a shot, one of the first things I do is shuffle the source reads RGB channels into a src_plate layer. By doing this I have created a new layer in my compositing stream that i can now get to at anytime. I can also do this with pre-renders of denoised source plates or maybe just the red channel for tracking. These can be shuffle copied into the compositing stream as well. Now when I need the source plate down the compositing stream I can use a shuffle node to bring that layer front and center.

There is a flip side to all these layers and channels. If you work with folks that do not use this method of compositing then this might cause a problem. Above all else when working with others in compositing is to have everyone on the same page. Above all else if you are working within a group keep your scripts readable and organized as you can.

Take some time and understand what your doing. There is nothing worse than not knowing why a image or matte isn't showing in the viewer.

Here is an example script to look at. And also a link to Nukepedia.com explaining more in-depth layers and channels. In this script there is SRCPLATE and SRCPLATE_CC. Both layers containing RGBA channels. There is also a roto node that is plugged into a copy. I am coping the roto nodes matte into the stream for future use.

        set cut_paste_input [stack 0]
version 6.2 v2
push $cut_paste_input
Roto {
 output alpha
 curves {AnimTree: "" {
 Version: 1.2
 Flag: 0
 RootNode: 1
 Node: {
  NodeName: "Root" {
   Flag: 512
   NodeType: 1
   Transform: 0 0 S 0 0 S 0 0 S 0 0 S 0 1 S 0 1 S 0 0 S 0 1024 S 0 778 
   NumOfAttributes: 10
   "vis" S 0 1 "opc" S 0 1 "mbo" S 0 1 "mb" S 0 1 "mbs" S 0 0.5 "fo" S 0 1 "fx" S 0 0 "fy" S 0 0 "ff" S 0 1 "ft" S 0 0 
  }
  NumOfChildren: 0
 }
}
}
 toolbox {createBezier {
  { createBezier ssx 1 ssy 1 sf 1 sb 1 tt 4 }
  { createBSpline ssx 1 ssy 1 sf 1 sb 1 }
  { createEllipse ssx 1 ssy 1 sf 1 sb 1 }
  { createRectangle ssx 1 ssy 1 sf 1 sb 1 }
  { brush ssx 1 ssy 1 sf 1 sb 1 }
  { eraser src 2 ssx 1 ssy 1 sf 1 sb 1 }
  { clone src 1 ssx 1 ssy 1 sf 1 sb 1 }
  { reveal src 3 ssx 1 ssy 1 sf 1 sb 1 }
  { dodge src 1 ssx 1 ssy 1 sf 1 sb 1 }
  { burn src 1 ssx 1 ssy 1 sf 1 sb 1 }
  { blur src 1 ssx 1 ssy 1 sf 1 sb 1 }
  { sharpen src 1 ssx 1 ssy 1 sf 1 sb 1 }
  { smear src 1 ssx 1 ssy 1 sf 1 sb 1 }
} }
 toolbar_brush_hardness 0.200000003
 toolbar_lifetime_type all
 toolbar_source_transform_scale {1 1}
 toolbar_source_transform_center {1024 778}
 view {}
 motionblur_on true
 name Roto1
 selected true
 xpos 3614
 ypos -43
}
CheckerBoard2 {
 inputs 0
 name CheckerBoard1
 selected true
 xpos 3608
 ypos -205
}
ColorBars {
 inputs 0
 name ColorBars1
 selected true
 xpos 3775
 ypos -381
}
add_layer {SRC_PLATE SRC_PLATE.red SRC_PLATE.green SRC_PLATE.blue SRC_PLATE.alpha}
Shuffle {
 alpha black
 out SRC_PLATE
 name Shuffle1
 label "\[value out]"
 selected true
 xpos 3775
 ypos -298
}
add_layer {SRC_PLATE_CC SRC_PLATE_CC.red SRC_PLATE_CC.green SRC_PLATE_CC.blue SRC_PLATE_CC.alpha}
ShuffleCopy {
 inputs 2
 red red
 green green
 blue blue
 out SRC_PLATE_CC
 name ShuffleCopy1
 label "\[value out]"
 selected true
 xpos 3775
 ypos -184
}
add_layer {roto roto.matte}
Copy {
 inputs 2
 from0 rgba.alpha
 to0 roto.matte
 name Copy1
 selected true
 xpos 3775
 ypos -43
}

Enjoy,

michaelb