The interpolated curves are only following the guide shapes and not the local density.* Done this way, long hair grooms need few interpolating guides to control flow while also giving enough hair density near the tip to style with modifiers. In this first of three videos we go over how to convert styled Ornatrix hair to Xgen. Use Xgen alongside Ornatrix to help you style and simulate hair, or to introduce Ornatrix into your existing Xgen -based pipeline. Attached is a similar setup in Xgen with a basic density map (Image 4). Ornatrix and Xgen, which comes with Maya, can be best friends. This kind of interpolation does not happen in Ornatrix or Xgen as far as I know.

Increasing the radius parameter beyond the set limit of 0.2 begins to inhibit the guide's ability to shape the generated hair and delivers unpredictable results (Image 3). You can still see noticeable segmenting near the roots and tips (Image 2). The “influence radius/decay” parameters in Houdini do not exactly resolve this issue as they are essentially hiding the clumping effect by increasing the radius of them. Note that in the shown example I am already using an attribute map to drive the density. This creates a clumping-like effect even without any hairclump nodes in the chain. Specifically, the guides are not only influencing the shape of the hair as we would expect but also the local density of the generated hair (Image 1).

nHair isnt used by Grooming TDs, as its purpose is simulation. If you want to learn grooming at home, play around with Yeti and Ornatrix, or XGen.

The default hair interpolation in Houdini behaves in a suboptimal way for grooming long hair. In XGen, you can groom the driver curves, like in Yeti or Ornatrix, while in nHair you convert the curves into dynamic curves, so you can simulate them.

Ornatrix vs xgen compare