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In this movie we're going to talk about how to add a bump texture to the mia_ material. I have a copper pot in this scene and an mia_ material has been applied to it, and I'm using the Chrome preset. The only thing I've done to it is I've adjusted the Reflectivity and brought it down to about 0.662 and I have lowered the Glossiness value a little bit, just toned down the reflections a little bit so that the pot itself is more visible. To add a bump texture I just need to scroll down to the bottom here, expand the Bump section, and I want to add my bump texture to the Standard Bump slot, not the Overall Bump slot.
The Overall Bump slot is reserved for the round corners node. I'll click on the checker icon to the right of Standard Bump. That'll pull up the Create Render Node. I'm going to choose a 3D texture so that the bmp is applied evenly without regard to the UV coordinates and I'll use Volume Noise. When I add a bump texture to a shader generally the Attribute Editor will switch to the bump 3D node or if it's a 2D texture it'll be the bump 2D node and this essentially controls the strength of the bump.
So the bump value is connected to the texture itself. So bump value is connected to Volume Noise, but the bump depth adjusts the strength of the overall bump. So I'm going to lower this down to say let's do it 0.1 to start with, and then I'm going to switch to the VolumeNoise tab and make some adjustments here just to change the pattern of the noise. Now the way a bump texture works is a grayscale of texture and the light values of the texture make the surface appear like it's bumping out; the dark values in the texture make it look as though the surface is bumping in.
It doesn't actually change the geometry of the surface in any way. It just creates the appearance of bumpiness in the render. So what I can do is I'll lower the Amplitude a little bit so you can see I am getting a little bit more gray in there, and that'll add a little bit variation, and I can change the Frequency by increasing this, bring it to higher frequency and lower the Density and you can experiment with the different noise types in the Volume Noise texture. It's one of the reasons why I like this particular texture. But I'm going to put it to Perlin Noise and see how that looks.
Let's do another render. So you can see now how the surface appears bumpy. It's a little bit strong so a couple of things I can do to adjust that is I can bring the Threshold up. You see how the texture is getting lighter when I bring that up and bring the Amplitude down so this is kind of like adjusting brightness and contrast. Let's do a little render region here and see how that looks. That's looking a little bit better. I'm going to graph the network, so I'm selecting the mia_material in the upper portion of the hyper-shade, right- clicking and choosing Graph Network, and now you can see how the network is connected.
So you can see how the bump3D node is connected to the Standard Bump channel using the Out Normal attribute. If you're using a 2D bump then this would be bump2D node as opposed to a 3D node and then the outAlpha of the texture is connected to the bump node here, so it's a single connection. Another thing that's kind of interesting to do is choose the same texture to control the reflectivity of the surface. So this'll add variation to the Specular Highlights. So what I can do is I'll just scroll up in the Attribute Editor, let me minimize Render View, and I'm going to scroll down to Reflection, and right-click VolumeNoise over Reflectivity.
Now I have the same texture connected to Bump and Reflectivity. So let's do a render. You can see how this is starting to break up the surface as well as the reflectivity and creating some interesting effects. Now I'm using procedural nodes for the bump value but you can also use file textures, so you can actually paint your own textures. When you create a bump texture if you're painting it in Photoshop, you just basically want to paint light and dark values and just remember that the lighter values are going to make the surface look like it's bumping out and darker values are going to make the surface look like it's bumping in.
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