"Texturing:
The Noise Map"
This tutorial will teach You how to use the Noise map to create a nice Rock texture. First however, let's go over the basics of the Noise map:
Create a Sphere with a radius of 100 units in the front viewport. Move it 100 units to the right, and create a Torus Knot (Extended Primitives, Base Curve radius=45, Cross Section radius=20). Because of the many curves and angles in the Torus Knot, we are better able to see the effects of the texture later on. Adjust the Perspective viewport so that You can see both objects.
Open the Material Editor, and apply any material to both objects. Click on the Diffuse map channel of the material, and choose a Noise map. The Noise map is a procedural texture, which means that no bitmap is used (which exist of pixels); instead a mathematical algorithm (do You know Fractals? The Mandelbrot? It's something like that) is used to create the texture.
One important thing to keep in mind when using a Noise map: Play around with it! Any parameter You might change can have a large impact on the end result. Usually You will find Yourself trying several combinations before You get the desired result. Now, though, on to the individual parameters:
The Coordinates Rollout - I won't go into detail on this here, it suffices to mention that the Noise map has the advantage of not requiring UVW coordinates. It can be mapped onto XYZ coordinates instead. Mapping types such as spherical, planar or cylindrical are not required. And as a result, You won't have any distortion problems, that may appear with UVW-mapping (especially with spherical objects).
One should be careful when using this mapping type on animated objects though - the animated objects will 'swim' through the Noise texture - which will appear to be static ¹. For our example, we'll let the Coordinates Source be at "Object XYZ"The Noise Parameters Rollout:
This is where the most important settings for the Noise effect are located, such as the Noise Type."Regular" is a simple varying pattern between black and white (I hardly use it). A little more complicated is the "Fractal" type. The difference from the "Regular" noise, is that You get more levels with the Fractal noise type. This means that the transitions between the blacks and whites isn't a smooth gray anymore, and instead is built up out of more detailed areas. The more levels You use, the more detail the transitions will have. Try it: render Your example objects once with the regular, and once with the fractal noise types. Change the number of levels for some more test renders. You will see that the fractal noise type looks just like the regular noise type if the number of levels is just 1. But the higher the number of levels, the more "chaotic" the texture will be. The Turbulence noise type is a bit of an oddball. It is more puffy, more cloud-like, than the Fractal noise type. Check out the differences... (Image 1 shows the three different noise types from left to right: regular, fractal, turbulence).Noise Size is self-explanatory.
The Noise Threshold values are very interesting: using the high and low values, one can change the balance (one could say contrast) between the two noise colors (which default to black and white). The "high" value defaults to 1, and the "low" value defaults to 0. This means that You get smooth transitions, with little contrast. Choose a Fractal noise type set to 3 levels, and slowly lower the "high" value down from 1 to 0. You can already see in the Material Editor preview, that the white color gains in area over the black color. The other way around it works the same. The balance is changed...
If, however, You change both values equally towards each other (high=0.9, low=0.1 / high=0.8, low=0.2), then the balance is not changed. Both colors retain an equal amount of space covered, but the contrast between them is increased - gray transitions get smaller. If both are set as close together as possible (high=0.501, low=0.499), the highest contrast has been reached - a chaotic white/black pattern without levels of gray. An example use for such a thing: imagine the frame for a door, from which a little paint has come loose. You've got two materials (Paint, and open areas at which rust has been formed) which You blend together based on such a high-contrast nose map. In this case You would set one of the two colors (the paint) to a much lower value (high=0.05, low=0.49), as it should be dominant on the object. Only small bits have chipped off (the low value). The number of levels determine the amount of chaos between the boundaries. For the "chipped-paint-example" a low amount of levels would be used, as paint chips off in a fairly regular fashion. You don't need a high amount of small details.The high/low values work a little differently with the turbulence map type. Revert all values back to their originals (high=1, low=0, levels=3) and choose the turbulence noise type. It's useless to go over the above again now, simply try changing the values Yourself (to be totally honest, I can't really think of the words to describe the effect). The turbulence noise effect is well suited for tears/cracks or cloud structures.
Using the Phase value, You can animate the Noise effect (Press the animate button, go to a different frame, and increase the Phase value).
Lastly, the two color fields: It doesn't always have to be back and white. You can also mix other colors together, or mix sub-maps using the noise texture. Whether it's a noise map in a nose map, a bitmap in a noise map, a mask map with a bitmap in a noise map... doesn't matter. The Material Editor allows for endless nestings (with the rock texture, that we will create, we will nestle a little as well :-))
Here we go:
You might think that I have MAX opened whilst writing this tutorial, and am testing that which I am writing down here first. But, for this rock texture... I have no idea at the moment what sizes and values I will need to use in the noise texture. These will become apparent during the course of creating the texture. So it may happen that we will have to change values later on, which we set in the beginning.
Drag Your noise texture from he diffuse channel to the bump channel, and choose "swap". Give the diffuse color a neutral gray color (128,128,128). Set the following values for Your noise map: Fractal, Size=1, high=0.6, low=0.3, levels=2. This will be our base noise effect. Give this map the name "Base Noise", so we better tell maps apart later on. Now click on the Type button, currently reading "Noise". The Material/Map browser appears. Choose a new Noise map, and from the appearing "Replace Map" dialog, choose "Keep old map as sub-map" - our first nesting! In the bump map channel of Your material, You now have the Noise map You just picked, and in its Color #1 map channel You have Your old Noise map. Your Noise is now a blending of white with a white/black blend. Name this new Noise map "Crack". Your Material Tree should now look like that in Image 2 ².
Use the following settings for Your "Rip"-Noise map: Type=turbulence, Size=25, high=0.25, low=0, levels=2. To distort the noise a little, change the x-tiling parameter in the "Coordinates" rollout to 3. In the "Output", check the "Invert" option. Make a test render from Your perspective view. The whole looks more like a dried out plaster effect than rock. It is too smooth.
We add a new map: the Cellular map.
It is also a procedural map, just like the noise map. Well suited for cracks, but also for warts and other skin protrusions. We will repeat a previous procedure; Make sure You are at the "Rip" noise map level in the material, and click on the "Type" button reading "Noise". The material/map browser appears again, and this time You choose Cellular > keep old map as sub-map > ok > voila! Our second nesting (there must be people who can't get enough of these).
Your two-level nested Noise map is now in the white cell color of the Cellular map. Using drag&drop, move it from the white cell color to the black cell color, choosing "swap" when prompted with the "Copy (Instance) Map" dialog. In the "Cell Characteristics" area, choose "Chips", check the "Fractal" option, de-activate the "adaptive" option and change the "Size" to 80. Lastly, give this new map "Chunks" Your material tree should now look like that in Image 3 ².
Make a test render.
Hmmmm.... looks more like dried out plaster, wrapped in crumbled up aluminum foil... Invert the Cellular map by choosing the "Invert" option in the "Output" rollout, and render again.
Image 4 shows what my material looks like now...
The cracks are too big. To make them smaller, we decrease the "Spread" value in out "Chunks" map to 0.25. This makes our cracks smaller, as a new test-render would confirm.
Still, the whole looks a little cold. Rock isn't just a dull gray. We need to color it...
To do this, I have copied the bump map into the diffuse map channel, and have de-activated all the "invert" options in my maps (so that the colors I will give it now won't be inverted, and yellow becomes blue). I have also swapped the sub-maps ("Rips" and "Base Noise") in the color channels. Then I assigned colors matching the structure of the bump map. Stone on the outside has yellowish colors, the thick cracks from the cellular map have dark, green colors (moss, growing in the cracks). Should this prove to be a bit dazzling, check out the example file!
Add a little shininess to the material, and we're done. Hopefully You're now enthusiastic about procedural maps and will play with them some more. As You see, they offer great possibilities...
Have fun!!
Notes from translator:
¹ To prevent this swimming effect, read a tutorial on locking down procedural textures.
² Except it will be in the language of the MAX version that You use, not necessarily German.