Base combiners setup

First, lets build a plank on which we are going to develop our wood material. Load the Cube primitive and resize it to 60cm W, 10cm D and 2.5cm H and set the plank model so that it is centered around the origin except that the top face of the plank is at y = 0.

Set the modeling window view to "Birds Eye". Create a new window (menu "Window", "New Window"). and set the view to "top" and create another window and set its view to "Right". Create a new material and name it "Wood Color". Right-click on the attribute and select "Change Type To", "Combiner" and "Spherical". Already set the first attribute color to white and the second to black. Drop the material onto the plank model. If you render right now, it doesn't look remotely like wood.

When I work up my materials, I always start with Black and White attributes. This helps me figuring what is going on with the settings of the properties. Only after I'm satisfied with the black and white patterns, do I start changing the black and white colors to real colors.

The plank is modeled horizontally so we're going to model the tree trunk horizontally. Select the Spherical combiner and set its scale to X=20000 (twenty thousand), Y=15, Z=15, Ring 1 Size = 1.5cm and Ring 2 Size = 0.5cm. Set Translate X = 30cm so that the center of the spherical is on the right edge of the plank and translate Y = -3 so that the center is just below the base of the plank. If you render now, it still does not look like wood.

We need to add some turbulence. Right-Click on the Spherical Combiner and select "Add Turbulence" and "Perlin". The Perlin turbulence will produce sharp turns in the turbulence pattern. Set its scale to X = 2000, Y and Z = 100 and Amplitude = 10. Now we got some irregularities in the lines but still not convincing wood.

We need to add some slow waving turbulence to the whole pattern, Add a "Fractal Sum" turbulence to the Spherical combiner. Set the scale to X, Y and Z = 20000 for the slow turbulence and the amplitude to 200. If you render, it now starts to have some similarity with wood.

But the pattern is still a little too regular for my taste. What is missing is some impression of wood fibers. So lets add another "Fractal Sum" turbulence to the spherical but this time, we need some tiny elongated fiber details so scale X = 200, Y and Z = 15 for tiny details and Amplitude = 3. Now we're getting somewhere.

So we have a simple spherical combiner which we scaled along the dimension of the plank and then added 3 different turbulences to add slow wavy effects, sharp medium transitions and tiny fiber patterns in the spherical.

Note that the order in which the turbulences are added is important. Adding them in a different order would produce different wood patterns and some of them might not look like wood at all.

An important notion to understand about combiners is that they are actually mixers or separators. In the case we present here, the Black and White nodes should not be viewed only as colors attributes, they may be complex material trees in themselves. Whatever the case, the black pattern we see here is the result of the value of the combiner letting passing only the attribute of the lower node. Conversely, the white pattern we see is only the result of the value of the combiner letting passing only the attribute of the upper node. By adding blur, combiners act as mixers. See my Combiners page for more.

Now set the Spherical blur to 50. We're clearly getting closer to a nice wood material.