When it comes to compositing its important to remember everything or near enough to everyhting.
Chromatic Abberation (CA) is one of those everythings...
What is Chromatic Abberation:
Basically CA is colour of light waves being refracted different. You are probably not aware but light is treated differntly when it passes through objects but is does, you just need to look at a diamond or glass prism.
Notice in the diamond how faces are refracting different colours, while the glass prisms caustics reflect from red through to blue.
Youre probably thinking where this comes into compositing, this effect doesnt just affect 3D glass refractions. The lens itself is also refractive (go figure....) and the lower quality the lens the more CA is caused (this is why CA is more common in camcorder lenses than in DSLR's). When the light is focused through the lens and the colours refracts to a different area on the CCD. CA is also most noticable when there is contrast between light and dark, similar to light wrap. Light wrap and CA are a great combo.
This diagram kind of explains the effect of CA
How do i replicate it?
There are a few plug-ins and scripts out there, but like with most effects you dont always have access to them and you are kind of left short.
When doing this type of effect you simply need seperate the channels out then radial/direction blur the blue and red channels, and lastly re merge the channels... Quiet a really easy process.
What about 3D?
Youre probably thinking where this comes into compositing, this effect doesnt just affect 3D glass refractions. The lens itself is also refractive (go figure....) and the lower quality the lens the more CA is caused (this is why CA is more common in camcorder lenses than in DSLR's). When the light is focused through the lens and the colours refracts to a different area on the CCD. CA is also most noticable when there is contrast between light and dark, similar to light wrap. Light wrap and CA are a great combo.
This diagram kind of explains the effect of CA
How do i replicate it?
There are a few plug-ins and scripts out there, but like with most effects you dont always have access to them and you are kind of left short.
When doing this type of effect you simply need seperate the channels out then radial/direction blur the blue and red channels, and lastly re merge the channels... Quiet a really easy process.
What about 3D?
Yeah what about 3D!
Now with some renderers you can have the option to choose dispersion with refractions. This will slightly alter the IOR of the indavidual channells. If your renderer doesnt have dispersion option you'll have to go old school on it. You render your reflections with slightly different IOR's then in post merge the different rendering into the red/blue channels (also bluring my be needed to help blend).
Conclusion
Chromatic Abberration is by far the best way to add that little extra something to your renders/composits, But you need to use it lightly.
Now with some renderers you can have the option to choose dispersion with refractions. This will slightly alter the IOR of the indavidual channells. If your renderer doesnt have dispersion option you'll have to go old school on it. You render your reflections with slightly different IOR's then in post merge the different rendering into the red/blue channels (also bluring my be needed to help blend).
Conclusion
Chromatic Abberration is by far the best way to add that little extra something to your renders/composits, But you need to use it lightly.
No comments:
Post a Comment