In today's quick tip, I'm going to show you how to modify the reflectance of your
Cinema 4D decal maps. By default, Cinema 4D only applies a Specular to materials.
Specular is sort of a fake reflection of the lights that are in your scene.
But it doesn't take into account the HDRI maps or illuminant objects that you might
be using to light and add reflections in your scene. So you can see here that the
"Sunscreen" text, especially, doesn't look like it's part of the tube
because it's not exhibiting the same reflections that the tube itself does.
So in order to fix this, what we need to do is match the reflections on the decal
map to the ones that we're using on the tube. For that we need to use a true
Reflectance layer. So I'm going to remove the Specular, and we want to add one of
these first four layer types. I like to stick with Beckman if I'm working with
plastics and GGX for metals. So we'll add a Beckman layer, and you'll see that
everything gets fully reflective. What we need to do is dial the reflection back in
order to see some of the color again. So we can do that globally using the slider
on the layer itself. So if I drop this down to something like 22%,
you can see that now we're getting a lot more of the color. But what we actually
want to do is adjust the reflectivity based on the angle to the camera.
Most things get more reflective as you're looking at them from the side than they
are when you look at them straight on. The way we control that effect in Cinema 4D is
the Fresnel. So when we go down here to the layer Fresnel, we can go ahead and
activate a Dielectric Fresnel. Dielectric is what you'll use for plastics and things
like that, while conductors are things that you'll use for metals.
So I'm going to activate a Dielectric Fresnel. Now you can see that we're
getting the color and we're also getting the reflections from that HDRI map onto
the label itself. Now I actually want to match the Index of Refraction to what I
used on the tube itself, which is a little bit exaggerated for plastic,
but I used a value of 1.76. As we increase the Index of Refraction,
the reflection itself will spread further into the center of the object.
Now we can go in and dial the full strength of this reflection layer up a
little bit more, and I'm going to go with something like 50%. The next thing I want
to do is actually make these elements that are yellow into a gold leaf on my label,
and for that I want to create a new Reflectance layer. I'm going to use a GGX
for this because I'm creating something that's more metallic.
Now what I want to do is limit this reflection to just the parts of the label
that are currently yellow, and for that what I'm going to do is go into the layer
mask. What we can do is load the same image that we're using elsewhere into the
layer mask texture slot. We'll jump into the bitmap properties,
and here we can access the Layer Set dialog. If you didn't watch my previous
quick tip, the Layer Set dialog allows you to access the individual layers of a
layered file format, like Photoshop, and choose which layers are being evaluated
for each texture. So for this I want to work with the Alpha channel of specific
layers, and I'm going to choose the yellow bar and the sun. So now
we're getting this reflectivity on just those two elements. I went with just the
actual reflection that's being cast, and for that I'm going to go down to the
Fresnel again. When we're working with metal, Cinema 4D has a special Fresnel
option called "Conductor," and this allows us to really easily simulate the effects
of different metals. The easiest thing to do is simply click on the Preset dropdown
and choose the metal that you're looking for. In this case, I'm going to use Gold.
So now you can see that we've got a gold leaf in those areas of this label that
were previously yellow. You can use Reflectance layers with layer masks this
way in order to dial in the specific reflection of different parts of your
material. If you want to go a step further, you can disable your color
channel and add the color through a Diffuse layer in the Reflectance channel.
We'll use something like the Lambertian Diffuse channel, and make sure to drag it
all the way to the bottom. Now in here what we want to do is go to the layer
color, and once again load our decal map. Again, I'm going to jump into the Layer
Sets dialog and choose all of the layers so that I can eliminate any effect of
pre-multiplication that might be adding a white fringe around my label.
Now, the benefit of adding a Diffuse layer within the Reflectance channel itself is
that now even the parts of the image that aren't reflective are going to take into
account the lighting of any other scene elements, like HDRI maps or illuminate
objects. So that's a quick overview of how you can adjust the reflectivity of your
decal maps in order to get the look you're going for, and have them look fully
integrated into the lighting and reflections of the scene. If you enjoyed
this quick tip, please like, share, and visit cineversity.com for more great
Cinema 4D tutorials and resources.