Blackmagic Forum

I've got a cloudy sky that the client would like blue, before we investigate sky replacement I told them I'd take a crack at it...My plan was to blow it out to lose the detail of the clouds and then do a few gradiants to make it look blue but not fake...My issue is that when on blow out the sky and start working the next node, when I pull things back the detail comes back in the clouds...I thought the nodes were a "waterfall" meaning if every next node is basing everything off the node before it? So if I nuke it in node 2 node 3 should just be looking at a bald sky...Appears that's not the case here and I'm curious if there's a setting when I can tell it do that...

I actually rendered it with the bald sky and then cc on the rendered file and feathered in some blue...but if anyone knows of a way to tell the node to only grade from the previous node it would be appreciated.

Its called concatenation, so you almost never lose information.

There are many ways to replace sky, if you want to try it this way then use curves to blow out the sky.

Curves don't concatenate, so if you clip something in curves, it's gone forever (edit: I believe it's curves that don't concatenate)

Stuart Smith wrote:Its called concatenation, so you almost never lose information.

There are many ways to replace sky, if you want to try it this way then use curves to blow out the sky.

Curves don't concatenate, so if you clip something in curves, it's gone forever (edit: I believe it's curves that don't concatenate)

Great information to have! Thank you!

You could try a node with a layer mixer, where you blow out the bottom layer, pull a luminosity key on the top layer and colorize it, then adjust the opacity of the top layer to mix.

I did something similar yesterday, but I wasn't trying to change a cloudy day into a cloudless day. I just wanted a touch of color in the sky. Sometimes subtlety goes a long way.

I agree with the idea to do this subtly. I don't think starting with a clipped sky is a good approach.

Look carefully at skies in real life and you'll see that they're never one shade of blue: there's almost always a "feathering" as it gets to the horizon. Making this look real in color takes a lot of experience and experimentation. (Even tougher if it's sunrise/sunset.) Tracking masks can work, careful qualifications can work, soft keys can work, but a lot boils down to putting the color where you want it and not where it doesn't need to be, and with zero artifacts.

Sky replacement is a whole separate VFX issue, and that can work provided it can be accomplished within the time and budget available. But in a lot of cases, I'll pop the skies and make them more "photogenic" without making them clip and yet also give them a little saturation and style.

There's so many ways to perform a sky replacement and fine-tune it in the end that I wouldn't have hesitated...