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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, we're going to talk a little bit about the mental ray specific attributes that are found on standard Maya shaders, shaders such as the Blinn shader and the Lambert shader, and these could be useful for creating specific shading effects. So in this scene, I have a number of teapots with different shaders applied. These are all my standard shaders, but I've adjusted some of the settings in the mental ray attributes section of each shader's attribute Eeditor. Let's take a look at what I've done.
On the orange teapot here in the far left, I've added some blurry reflections. You can see them right here. So let's take a look at what I've done with the shader. I'm going to select the teapot and open up its Attribute Editor to the blurryReflectionBlinn tab. This is the shader that I've created for this particular teapot. And it's a standard Maya blinn shader. There's nothing too special going on. I've a kind of dark orange for the color. Most of the other settings are the default settings.
I've adjusted the specular highlight a little bit by decreasing the Eccentricity. For the most part it's the default settings. Now let's go down in the Attribute Editor to the mental ray section. So these attributes are only effective when you're rendering with mental ray. If you render with Maya software, these attributes won't do anything. In order to create the look of blurry reflections, I've gone down to the Mi Reflection Blur slider and I've set this to seven and I'm going to zoom in here and do another test render, so we can see what this looks like up close and it is something like this, and let's do a quick test render.
So, you can see that in the reflection of the scenes of the elements in the environment, how that they're slightly blurry, indicating that the surface might be a little bit rougher or slightly imperfect. You can also see how that the reflections here closer to this edge are sharper than those of the elements of the scene that are farther away from the surface. They get more blurry. So it's even easier to see here at the spout. Parts of the spout that are closed to this surface, the reflection is sharper than parts of the spout that are farther away from the surface. It's a nice-looking effect and it's very easy to achieve.
Just take a quick look at the settings, the Reflection Blur, this setting controls how blurry the reflections are going to be. The Reflection Rays, this can be used to increase the quality of the blurring. Lower settings are going to result in more grainy looking reflection blur. Increasing this setting will add to render times, so be careful a little bit. The Reflection Blur Limits sets the number of times the Reflection Blur itself is going to be seen in other reflective surfaces. So if I had a number of other reflective surfaces in the background here, this will set the number of times that the blurred reflection effect is seen in those surfaces, as it reflects this surface.
It's really just a way to optimize it. If there's no other reflective surfaces around, you can set this to one or two and it will be just fine. So that's Reflection Blur, fairly simple to set up and can add a very nice quality to your renders. I like to use it when I'm rendering something like a shiny floor, such as like a hardwood floor that might be reflecting like windows in a room. You want it kind of blurry, so it looks little bit more realistic. On this teapot here, I have any Lambert shader, just a standard Maya Lambert shader, and I want to point out that notice that the c odor of the shader is gray.
I've a fairly low Diffuse value. When I create a render, let's take a look at how it results to the surface. Now I'm rendering with Final Gathering on, so you're going to see that it takes two passes to do the render. First it calculate the final gathering rays and then to calculate the render itself. So what I've going here is there's a slight subsurface scattering quality applied to the shader in the Lambert shader settings. So this is where the greenish color is coming from. It's almost giving kind of the look of like clay or something like that.
So it's like a nice like clay pot kind of shader. So as the light hits the surface, the photons of light are bouncing around within the surface and then coming out again giving it the slightly translucent effect. To create this effect, I've gone down in the Lambert shader settings to the mental ray section and I've increased the Scatter Radius setting. I've set this to 2 and I've created a yellow color for the Scatter Color. So that's why this gray shader is rendering out in this sort of greenish yellow color, because that's the result of the scatter settings. So once again take a look at the render itself.
The other settings in this section will control the quality of the subsurface scattering effect. So the Scatter Accuracy will increase the quality, but also increase render times. You can set Scatter Falloff similar to setting a light falloff, so right now I have it to None, but if we set it to Linear and Quadratic or Exponential, that's going to change the falloff of the subsurface scattering effect. Let's do another quick render of this teapot right here.
And in this one I have a transparent surface but I've activated Refraction Blur, so this is going to create kind of the look of frosted glass and this again, this is a standard Maya shader, this is just a blinn shader and I've turned the reflections down a little bit, so that you can clearly see the effect in resulting render. So here's the end result. The refractions closest to the camera are little bit sharper than those that are farther away. So as light passes through the glass, the further it passes, the more blurry the refractions get.
So let's take a look at how I've created this effect. If I go to the blurry_refraction_blinn tab here, this is the shader applied to this surface and let's take a look at some of these attribute. I just have a green color for the surface itself and I've lowered the Diffuse a little bit, and in the Specular Shading I've lowered the Reflections just to make it a little bit more clear. Under the Raytrace Options, I've turned on Refractions and I set the Refractive Index to 1.1. So these have to be active in order to get this effect.
I've also increased the Surface Thickness, just to give it the look of more slightly thicker glass. But the most important settings to achieve this effect are found again in the mental ray section down here. So I scroll down, I've increased the Mi Refraction Blur setting to 3, and this is very similar to the way Reflection Blur works. So the higher this is, the blurrier the reflection. The Refraction Rays, this increases the quality of the blurring. If the blurring effect you see in your surface is very grainy, you can increase Refraction Rays, but again this will increase render time and like Reflection Blur, the Refraction Blur Limit sets the number of times the blurring effect can be seen in other surfaces in the environment.
And then finally the last mental ray specific setting I want to point out is the Irradiance setting. So I'm going to select this teapot here and open up the irradiance_blinn tab. This is the shader that's been applied to this surface. And in the mental ray section, you'll see that I've increased the Irradiance value to a light gray and then set the Irradiance Color to kind of a fuchsia. And this is why I have Final Gathering turned on, because this effect is only going to be seen when you have some kind of indirect lighting such as Final Gathering or Global Illumination, and what this setting does is it controls the color of the bounced light.
So as light hits like the floor and then bounces and then hits the surface, those photons of lights are going to be colored based on the Irradiance settings. So this is a way you can fine-tune an individual surface in a scene that uses indirect lighting such as final gathering. I have just set this to purple, just to make it nice and obvious, but you can use more subtle colors depending on the effect that you're trying to get. That's a brief overview of how you can use the settings found in the mental ray section of standard Maya shaders to create specific effects.
So this surface has some Reflection Blur set to it. On this surface I've increased the Scatter Radius to create kind of a subsurface scattering effect. On this surface I have blurry refractions to make the look of frosted glass, and on this surface I've increased the Radius value and added a slight color to the Irradiance Color. Now of course, mental ray has a wide variety of shaders that can also create these effects and in some cases can do much more sophisticated versions. But the reason that I might choose to use a standard Maya shader with the mental ray attributes adjusted is that it's very simple to achieve the effect very quickly and it tends to render fairly quickly as well.
So if I just need a very simple, blurry reflection over a simple look of frosted glass, I would choose to use Maya standard shader with the mental ray attributes adjusted, as opposed to using the mental ray shaders which have more controls that may be a little bit more complicated.