Join Aaron F. Ross for an in-depth discussion in this video Customizing a chrome material, part of Creating Product Shots in Maya.
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We don't have a chrome material on the watch yet. However, the environment is actually illuminating the scene because we've added a bitmap to the additional color attribute. Let's just take a look at what that does if we have final gather enabled. Go into the render settings. And go into Quality, and just set this down a little bit, so that it will render more quickly. I'll set the quality to 0.25. And then under indirect lighting, we previously turned on final gathering, and set accuracy to 100, point density to 0.5, point interpolation to 100.
And secondary diffuse bounces to one. Close that dialog, highlight the view, and then click Render. After about 30 seconds of rendering, this is the result that we get. And this blue tint is coming from the environment. The final gather is actually allowing light from that self illuminated sphere to illuminate the seam. And it's adding to the area lights that we've created explicitly. Alright let's store that so we can compare that to other versions. Also notice that we don't see the environment here in the background.
And we don't see it in the alpha channel either. As you can see here. And the reason of course is because previously we set the render stats to that object so that primary visibility is turned off, which means that the camera can't see it. Alright, cool. Minimize that, and create our chrome material, we'll want to select the watch body objects. So right-click on the watch body layer and choose Select Objects. And then create a new material, right-click on one of those objects, assign new material. Once again its a mental ray material, mia material x passes.
And rename it, and I'll call it chrome mia. We'll start from the chrome preset but we'll have to make a lot of adjustments to it. Go to the presets button, hold that down and choose Chrome > Replace. And while we're at it we can assign the chrome material to the watchband. Right-click the watch band layer, choose Select Objects, right-click on the watch band and choose Assign Existing Material > chrome_mia. Now that's assigned. We can go to the chrome_mia material and let's copy the tab off so that we can deselect the objects and still see the attributes for that material.
Now I've got a copy of the attribute editor and we can deselect our objects and not lose what we're working on. Okay, so we've got a lot of attributes to work on here. First of all we want to increase the diffuse color up to white. And that's going to actually add a lot to the look of this, but then once that's turned up to white, we're going to reduce the weight of the diffuse amount. Down to lets say 0.3. What this is doing is it's going to give us a little bit of shading on that surface so that we'll have some modeling or some gradient between light and dark.
If it didn't have any diffused component at all then it wouldn't look terribly realistic. We need to have some diffuse amount. We want a white color here with a low diffuse amount. And that gives us just what we want. The roughness here we'll set to zero. Because it's going to be a highly polished surface. We come now to reflections. And this is almost where we want it to be. We do want white reflections, and we do want the reflectivity up all the way to a value of one. But additionally, we want the glossiness turned up all the way to its maximum of one.
If we had a glossiness of 0.5, we would get a sort of brushed metal or satin metal look. And what we're going for here is something that's very highly polished. There are a couple of options down here I'll just mention in passing. Highlights Only would disable reflections. We would only get specular highlights from the lights. And we wouldn't see the environment in the surface, so we don't want that on. You'll also see Metal Material, and you might think that should be enabled but I recommend against it. Because what it does it combines the diffuse and reflection colors in a way that's not immediately intuitive.
It makes it more difficult for you to control them because they interact. Therefore I just recommend leaving it off. Allright, so let's go into the Advanced Reflections section just to take a look at that, as well. And you will see, importantly, the Max Trace Depth. This is how many times a ray can bounce the reflections. And it's currently set to three which is a good number and that's where we want it to be left. These other options are good options, as well. You'll see no highlights for visible area lights. So, if we had enabled visibility in our area lights, and this switch was off, then we would see the area lights in the reflections.
But, as I discussed previously in the lighting chapter, it doesn't really work very well. It doesn't really do what you want it to. So for that effect, we've created these white cards, remember this. So, we're not using visibility in the area lights anyway. So, it doesn't matter whether this switch is on or off. But it is on by default, which means that if you want to use that feature, you'll need to turn this switch off here. Alright, moving down. Scrolling down a little bit, you'll see refractions. We don't have any refractions here in this case.
There's no transparency. So it actually doesn't matter what we set here, except, the settings in refraction affect the BRDF settings. So, BRDF is the reflectance curve. It stands for bidirectional reflectance distribution function. Reflective objects tend to be shinier, and brighter, on the edges and less so in the center. And if the switch the says Use Frenell Reflection were on, then the setting for the reflectivity based upon face angle would be derived from this index of refraction here.
We want to have custom control over the reflectivity. So we don't want you use frenell reflection. So we'll turn that back off again. And these values that we see here, are actually pretty good values now. 0.8 or so, for the zero degree reflection means that the faces that are pointed directly towards the camera, at zero degrees to the camera, are going to be dimmed down by about 20% of maximum brightness. However on the edges of the object, where the surface normal is at right angles to the line of sight of the camera, or 90 degree reflection, we want full brightness on those reflections.
On the edges. Then we come to the BRDF curve, and that's just the simply the transition or gradient between these two values. And if we give this a lower value it's going to cause the 90 degree reflection to spread out a little bit more and brighten it up a little bit. So I'm going to reduce that just a bit to a value of three. And then finally there's another very important option. It's an attribute that's hidden in here under Advanced. Open that up and you'll see Specular Balance.
And this controls the brightness of specular highlights that are coming from the lights. So the reflection brightness is controlled through the BRDF settings, and the specular brightness is controlled here. I'll leave this at its default value of one right now, and let's see what it looks like. And if we need to we can come back in here and adjust this up or down. Good, so we can close this. Close the attribute editor. Highlight that view port by clicking in it and do another test render. Here's the result of that test rendering. And as you can, see it's looking a bit grungy here, we're getting a lot of grain.
That's just because we've got pretty low quality settings for our area lights. Remember the high sample value. We can increase that to make that specular highlight look better. And also, just the sampling rate in the mental ray render settings is set to a draft quality setting of 0.25. So, that's why that's looking so grainy. But the chrome material is actually looking pretty much the way that we want it to. And let's compare that to the diffuse material that we had by default. So here it is with that diffuse material, and then with the chrome reflective material.
And if you look closely you'll notice that the brightness of the ground plane has changed. And the reason for this is that we've reduced the diffuse amount. In this version, we've got a very high diffuse amount, and we're getting a lot of bounce light here from the final gathering. And once we've reduced that by knocking it down to a value of about 0.3, we're getting a lot less diffuse reflection here. So once again, high diffuse amount gives us a lot of bounce. A low diffuse amount is reducing the amount of bounce.
Want to learn how to create the same effect with 3ds Max? Check out Creating Product Shots in 3ds Max.
- Understanding the scene layout, hierarchy, and display layers
- Working with mia_material_x
- Creating and optimizing mental ray area lights
- Generating reflections with self-illuminated white cards
- Providing indirect illumination with Final Gathering
- Image-based lighting with high dynamic range files
- Rendering to a 32-bit file format
- Saving material and lighting components to render passes
- Adding ambient occlusion
- Layering and color correction in After Effects