Join Eric Keller for an in-depth discussion in this video Introducing the mia_material, part of Creating Textures and Shaders in Maya.
In this movie we are going to introduce the mia_material. This is the Mental Images Architectural Material. This is my favorite mental ray shader because it is essentially a Swiss Army knife. You can simulate seventy different types of surfaces using this material. So, I am going to start in this scene, and I just have a familiar teapot model on a checkerboard. The first thing I want to do is I set up some lighting. Now the mia_material, the idea behind it is that it's a physically accurate light.
In other words, no matter what you do with the settings, the settings are always going to accurately simulate the physical properties of real-world materials. So, a good way to start playing with this material is to set up some physically accurate lighting and that can be easily achieved using the Physical Sun and Sky network. So, let's set that up really quickly. I am going to go to Window > Rendering Editors > Render Settings. Under the Render Settings, I'm going to click on Indirect Lighting and at the very top under Environment, I am going to choose Physical Sun and Sky.
So, I'll just press the Create button this will create the Physical Sun and Sky network. You also notice that it turns on Final Gathering, which will take care of our indirect lighting. This is actually very easy lighting setup to use. In the outliner, I have a sunDirection node. I am going to zoom out a little bit and pull up the directional light that is created when you activate this lighting network. I am just going to rotate it a little bit so we get something more like a late afternoon or early evening type of lighting.
So, let's do our test render. Currently, the teapot has just a regular old Lambert applied. Let's do a test render so you can see what the lighting looks like. So, here is our lighting so far, and you can see that we have a nice bluish shadow that's reflecting some of the indirect lighting of the sky. What I am going to do is just rotate this a little bit more, and zoom in, and do another test rendering just to make sure we have a good decent angle to start with. So, that's looks pretty good.
You'll notice in the Attribute Editor for the sunDirection node, the way you control the lighting is on the mia_ physicalsky tab, and the reason I want to point this out is notice the mia_ prefix here. This is an indication that this lighting scenario works very well with the mia_ shaders, they are designed to work together. So, I am going to choose Window > Rendering Editors > Hypershade and in the Hypershade under mental ray > Materials, I'm going to choose the mia_material_x material.
The X stands for extended, which means this material has some extended capabilities. Most of that is in the backend, so you don't really need to worry about it too much. Generally speaking, I usually either use the mia_material_x shader or the x_passes shader if I know I am going to be using render passes later on. But I'll just start with this one. Just click on the mia_material_ x button to create the shader. I am going to remove the Hypershade out of the way, select my teapot, and right-click over the shader and choose Assign Material to Selection.
So, now with that applied let's do a quick test render to see what the default settings look like. So we essentially have a shiny white pot as a default setting. Let's store this image. So what I want to do is give you a brief tour. This is an overview of how the shader works. So, I am going to select the shader in the Hypershade and open up the Attribute Editor. Let's take a look at the attributes. There are a lot of them, but you don't need to use all of them. You only need to play with the ones that you want to use.
So, let's start by seeing how we can create something that looks a bit like a translucent plastic. Up here at the top we have the Diffuse Settings and the way that the settings are arranged in the Attribute Editor is the more commonly used settings are at the top of each section and then less commonly used settings are towards the bottom. So, for example, under Reflection we have basic reflection settings and then below that we have Advanced Reflection settings. So, we don't always need to use Advanced Reflection. Usually wanted to see what you can get away with using the basic controls and then if you need to add more advanced properties, you can start to use the lesser used settings.
The other thing that's nice about this is if you hover the mouse over these settings, you get a little hint as to how each setting works, so that can save you some trouble from digging through the manuals. Let's start by creating a blue color for the Diffuse channel. So I've clicked on the color swatch next to Diffuse and I'm going to create a blue somewhat desaturated color here just by dragging in the color chooser. Something like that should work well. So, the Weight is the overall strength of the Diffuse channel, so as I pull this down it becomes darker, because less light is being defused by the reflection as it bounces off the shader.
I want to set it to about something around 6.4 is fine, and the roughness also helps to add some of that diffuse reflective quality to the diffuse reflections. Under Reflection, we have Reflection Color, as well as Reflectivity. So it is the strength of the reflection and then this influences the color of the reflection. So, I am going to bring the color of the reflection say to like a similar purple here and I am going to leave the Reflectivity at about 0.8 is fine.
Then since this is going to be sort of a plastic, I want to make it kind of a dull or blurry reflection. To do that all I need to do is lower the Glossiness setting. So, a very high setting, I am going to get very clear reflections on the surface. At lower settings this is similar to using Reflection Blur on the Maya standard shaders, Blinn or Phong or those type of shaders, and then the Glossy Samples controls the quality of settings. So the higher this is the less grainy the reflections are, but the longer it takes to render. So, I am just going to set the samples to 12 for now.
These two settings, just very briefly, the Highlights Only means that their environment will not be reflected just the specular highlight. Metal Material will add a certain amount of the diffuse color into the specular highlights. When I turn this on you can see how we have now purplish highlights, and that's good for like painted metal colors and that kind of thing. So, so far we have our Diffuse settings set up and our Reflective settings, so let's do another test render, and there we go. Wwe get something that's kind of like a shiny plastic kind of color. You can see nice broad specular highlight, blurry reflections.
They are not too strong but they are physically accurate, so it look quite nice. The next thing I want to do to add a certain amount of translucency is come down to the Refraction settings, and this is similar to the Reflection settings. In order to make the material look transparent I have to set the Transparency value to something above 0. So, I'll set this up to about 0.7. The Glossiness setting, again, this is for creating blurred refractions, just like with the reflections.
If I lower the Glossiness value in the Refraction settings I am going to get blurry refractions, making the material look more translucent. So I am going to bring this down to about .3. Maybe I'll pump up the Transparency a bit. The Color setting affects the color of the transparency, so if I set this up to like purplish blue, this will make it look more like plastic. So again, I am going to do a test render and see what we come up with. It's starting to look somewhat transparent and somewhat translucent, but I think we can improve that a little bit by increasing the Transparency up to 1, and I am going to lower the Index Refraction.
Right now, 1.4 is approaching something like glass. I am going to set this to 1.1, maybe make Color a bit lighter for the Transparency, and I am going to set the Glossiness to about 0.5. This is essentially the workflow that I go through when I am using the mia_material. It's really a matter of just figuring out the type of shading that I want and then playing with the settings until I get something that's close. So you can see now we are on our way to getting something that looks like a translucent plastic. I can improve the quality of the Refractions by increasing the samples, because this is looking a little bit grainy.
In my mind, the blurriness of the Reflections does not exactly jive very well with the blurriness of the Refraction. So I will just go up here and lower the Glossiness of the Reflections a bit, so they are a bit duller. Then I am going to increase the Glossiness settings under Refraction to about 16, so it looks a little bit less grainy. So that's just using the basic Reflection and Refraction settings and then we have more advance settings under here, under Advanced Refraction. So let's see what kind of result we get just using this standard refraction controls.
I want to just do another test render. So as you can see, it's already looking pretty good with just a little bit of twirling some of the norms. As we get more into the material, we will see that it's really quite flexible and very advanced.
- 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