Roto + Keying NUKE - 25/04/2014
Nuke Notes – Roto and Keying (25/04/2014)
- When working with things on a green screen, you'll use the gamma channels and RGB to see how the colour is unevenly distributed. E.g. brunette hair still has some green in the hair, need to carefully key out.
- Things like fine fur cut up the green into more washed out, and poorly distributed colour.
- ck the grain, shows up most prominently in the blue channel.
- Try and distribute the background green evenly with minimal distortion, and even lighting.
- Watch out for reflections.
- Be aware of the edges. Make sure the green doesn't cross over, or that the object doesn't cross over and tracking point.
- Think about what your background is going to look like. Will it be light or dark? Noise will show up less in dark conditions.
- Primatte is a very powerful keyer, allowing you to choose certain colours to key out, using CMND + Shift to select a specific area. You can also select operations in the properties, so you can clean the BG noise, Clean FG noise,...to fine tune the detail.
- Key light (for fine detail)
- Premult will cut out the white/black, and make it an alpha.
- You mask off the main areas that don't have an edge contact with the greenscreen/background.
- Use screen gain and Screen Balance to adjust the edge blend.
- Use hueCORRECT to pick out on the finer green tints between hairs and such. Usually the stuff along the edges. We can use 'green suppress' as a pre-set to alter the green.
- Grade both pieces of footage to match. Consider strength of whites and blacks. Blacks may be stronger in one clip, so adjust them to match, by either lowering or raising on a particular clip.
- Raise and lower the gamma to see this clearly. The blackest blacks will stay darker for the longest. You can also compare saturation in this way.