Cloned hairs can also be used to render cloth in close-up shots. The key lies in the way in which the splines are modeled (individual loops were created using a
Interpolation
Since it would be impossible to style hair one hair at a time, guides (far fewer in number than the actual hair) are used to roughly indicate the hairstyle. A great number of hairs will be interpolated between these guides. The closer a given hair is to a guide, the more it will conform to the shape of that guide (the effects of any Hair material settings will subsequently take effect). The Interpolation setting defines how the hair should conform to the shapes of the guides. A depiction of the different interpolation options is shown below.
Each type of interpolation applies its own particular falloff to each individual guide. This effect is illustrated in the image above, where hair was interpolated between a very short and a much longer guide. Simply imagine any of these interpolations on an entire surface and you will have a good idea of how each interpolation works.
Interpolated hair searches for the guides nearest to it and will conform accordingly. From Guides defines the degree to which individual hairs will be influenced by the guides (hair located closer to the guides will be influenced to a greater degree). The larger the value entered for From Guides, the more flowing and homogeneous the interpolation between guides will be.
Use the Variation setting to randomly vary the interpolation of individual hairs, causing the hair to look less uniform and more realistic.
Activating this setting will basically turn off free interpolation between guides, and attract the hair to the nearest guide, letting you easily create clumps of hair. A similar function, which offers greater control, is available in the Clump channel of the Hair material.
Use this curve to define the strength of clump creation over the length of each hair.
Various Interpolation Settings and Their Resulting Effects.
At the top left of the image below, the distribution of guides is shown, as used for each of the examples.
The following variations were then applied: