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- Understanding shading concepts
- Simulating the Fresnel effect for realistic reflections
- Rendering transparent and translucent surfaces
- Comparing mental ray and Maya standard shaders
- Introducing the mia_material
- Developing shader networks
- Using subsurface scattering shaders
- Mapping polygon UV coordinates
- Incorporating texture nodes into networks
- Improving skin detail with ambient occlusion
- Painting bump maps
- Creating normal and displacement maps
- Troubleshooting maps
Skill Level Intermediate
In this movie, I'm going to show you how you can use some of the utility nodes to affect the shader networks that you apply to your surfaces. So I have a teapot here. I'm going to select this teapot, and just create a blinn material by clicking on the Blinn Material in the Rendering shelf, just applies the Blinn material to the teapot. Now I'll open up the Hypershade by going to Windows > Rendering Editors > Hypershade. I'm going to right-click and choose Graph Materials on Selected. Here is my blinn texture. The Utilities nodes are down here under the Maya section.
There is a whole bunch of them. We can use them for a variety of effects. I'm going to do just something fairly simple. What I want to do is I'm going to use a Sampler Info node to change the way that colors are applied to the surface of this object. So I'll go back up to Maya 2D Texture nodes and I want to just create a ramp texture. So I'll zoom out in the Hypershade, you can see the ramp and the samplerInfo node and the blinn shader. So I'm going to middle mouse button+ drag the ramp shader on top of the blinn node and choose Color.
That connects the color of the ramp to the color of the blinn material. We can see how this looks in our teapot. Now the problem is, the ramp is being applied based on the UV coordinates of the teapot. So if I select the teapot and choose UV Texture Editor, this is what I got. The red areas are mapped down here and they're being spread across the flattened UV coordinates, which means that I have very visible seams in the different parts of the teapot. So what I can do is I can override the way the ramp is placed on the blinn texture using the samplerInfo node.
So I'm going to middle mouse button+ drag the samplerInfo node on top of the ramp and choose Other. This opens up the Connection Editor. I'm gong to connect the facingRatio here at the bottom of the samplerInfo node attributes in the connection area editor to the v coordinates of the ramp. So I want to expand UV Coordinates and choose v Coordinates. You can see now there is a connection being made. If I hover over it, you can see samplerInfo1.facingRatio is connected to ramp1.vCoordinates.
So I'll close the Connection Editor. We'll do a render and see how this works. So you can see the blue areas are the areas that face the camera and the red areas are the parts that face away. So this is creating this kind of effect. You can use this kind of technique for a number of things. For instance, if you wanted to create something like an x-ray shade or something like you can see in a scanning electron microscope, what you can do is I'll disconnect the ramp from the color channel just by selecting this connection and pressing Delete. I'll middle mouse button+drag the ramp over the blinn texture, and choose incandescence.
So this is sort of the brightness value, or the glowing value of the shader. I'm going to pull the Diffuse channel all the way down to 0. So we'll only see the incandescence colors when I do a render. The other thing I'm going to do is I'm going to pull the Reflectivity all the way down to 0. So when I do a render, we get this kind of look. Now I can adjust the ramp. We know that the red color at the bottom of the ramp is matched to the edges that face away from the camera. So I want to turn that to very light blue.
I'm going to delete the green color by clicking on the box here, the middle of the ramp to get rid of the green color. I'll select the blue color at the top, and set the color all the way to black, and maybe pull this down a little bit. Now when I do a render, we get this kind of sort of x-ray shading look to it. If I wanted to, I could set the Transparency fairly high. So it's going to look at kind of like a little x-ray here. Kind of an interesting effect, sort of the classic x-ray look that you can apply to your objects.
That's done with some basic utility nodes. What I want to show you is how you can also use a similar technique to create a fresnel type reflection in the blinn texture. So I'm going to disconnect the ramp from the incandescence channel. Then I'm going to increase the Diffuse settings, so that we can see the diffuse color. I'm going to set the Transparency back to 0. I'm going to bring the Specular Color up to white, and lower the Eccentricity to have a tighter highlight there. Now what I'm going to do is I'll go to the Utilities section in Hypershade and I'm going to click on Remap Value.
So this node is similar to the ramp. It has a graph that you can use to change the way values are mapped over the surface of the object, and also a color ramp, which is similar to the Ramp node. It's a horizontal as opposed to vertical node. Now, what I want to do is I'm going to connect the samplerInfo node to the remapValue node. So I'll just Middle Mouse Button+drag samplerInfo over the remapValue in the Hypershade and I'm going to choose Other. Again, I'm going to choose facingRatio. This time I'm going to select inputValue. Once I've done that, I'm going to middle mouse button+Drag remapValue on top of the blinn texture.
I'll choose Other again to pull up the Connection Editor. I'm going to choose outValue here on the left. So this is the remapValue node right here. This is the outValue attribute of the remapValue node. On the right, I'm going to select Reflectivity, which is down here towards the bottom. Let's do a render. It's not terribly obvious what's going on right now, but let's take a look at how we can adjust the ramp to make more of that fresnel type reflection.
So I'll minimize this and I'm going to go here and just start to edit the ramp. This side of the graph corresponds to the parts of the surface that face away from the camera, and this part of the graph corresponds to the parts of the surface that are facing the camera. So I'm going to make this kind of a stream here and do another render. Now you can see how we're getting a fresnel type reflection. The edge is here that are facing away the camera are more reflective than the parts that are facing the camera. I can pull down the Diffuse value to make that more obvious and increase Specular Rolloff and that'll make the reflections more intense, then create another render. There we go.
Slightly more realistic reflections applied to the surface of the teapot. That's the idea behind utility nodes. They're meant to help you expand the capabilities of your shader networks.