Join Adam Crespi for an in-depth discussion in this video Setting blending modes and adjusting opacity, part of Rendering Exteriors in Maya.
In NUKE, it's important to get everything, read or imported in. And get all the links or merges together and then think about the blending modes. As you get faster you may find you can merge instead of blending mode. But a lot of times, I prefer to get the tree kind of, set up first and then think through the different. Operations or blending modes for each set. I'll start out with my dusk imagery, getting the ambient occlusion and specularity pass to read correctly. I'll pull them up, zoom in, and enlarge my viewer just a little bit.
I'll click in the viewer, and press H to fill or fit that as well as possible in to that frame. If we press F, we'll be at, an even magnification. In this case, one third size. Pressing H, though, fits it. And we're dealing in a. 2.35 times which is something odd and I may get some aliasing artifacts. I care about the color not about the edges at the moment, and so I'm okay with just the fill. Now, double-click on merge three. It pops up to the top of the properties tab, and I'll set the operation to, multiply.
I'll press 1 to show this and, there's our ambient occlusion. Here's the difference. When we showed just the dusk beauty, everything is, well, fairly bright and, somewhat shadowed. But some things tend to float a little bit and the plants are very, very bright. What ambient inclusion does when we multiply it over then, is add grounding darkness everywhere. Here's how this works. Multiply is a math operation and multiplies, the overcolor times the undercolor and divides by the color space.
So the result is always darker. In multiply then. Multiplying by white is like multiplying by 1, there's no net change. So in an ambient occlusion, where most of the surfaces are, white the white disappears and we're left with just those grey tones, multiplying over and darkening the detail. We can see though that I lost the sky. When I show the beauty again by pressing 1 there's a faint physical sky behind, which I'm going to use for my background. What I'll do then, with that merge selected is grab the right side, mask arrow.
And I'm going to mask this by the ambient occlusions, alpha. My sky returns and, now I'm ready to get the spec pass looking right. I'll double click on Merge Four. Press 1 to show it, and over in the properties tab, set the operation for the spec pass to, screen. Screen is the inverse of multiply. In screen, screening by black, is like dividing by 1, there's no net change and anything lighter than black, screens over it. What it gives us then, is that subtle highlight laid over those images and, makes the black go away, giving me, a little bit of, well, extra pop on that concrete wall.
What I'll do with screen, is back off the mix just a little bit. Right now that screen is nice, but it's kind of muting down my, F.Smith sign's red glow. So I'll pull this back, so its just a little extra specularity. The mix amount here in NUKE, allows us to blend these back, going anywhere from 0 to a 100% opacity and really dialling in the, image where we want it to be. Now I'll set the blending modes and mix for my daylight scene as well. Here in my daylight flow, I'll organize a little bit.
I'm going to, select all these nodes and I'll press L for layout. Then I'll zoom in on that nice, concise flow. First I'll double click on merge 1. And I'll set the operation to, Multiply. I'll show it by pressing 1, and there's our ambient occlusion over the day. It needs to be masked as well, so I'll grab the mask node from the side of merge 1, and put it onto the ambient occlusion. There's my sky coming back in. And now I'll double-click on Merge 2, press 1 to show it, and set its operation to, Screen as well.
I'll back off the mix just a little bit, and now there's a little bit of my specular highlight across that building. Once I've got all the opacity and, different blending modes or operations set, I can start to think about, effects over the whole image, such as depth of field and glow, and also color correction on specific parts. Maybe pushing around the color of the brick just a little bit, or deepening everything overall for a little more contrast.
- Creating exterior materials
- Converting paint effects for mental ray
- Positioning the sun with the Daylight system
- Lighting using HDR imagery
- Lighting interior spaces
- Adjusting and optimizing the render settings
- Setting up additional rendering passes for compositing purposes
- Compositing and adding post effects in Nuke and After Effects