Adapting existing hair models

Last updated: 08.07.2001

Constructing new hair models from scratch is a fairly complex process and one that requires a non-trivial amount of skill. It is often easier to take an existing model and modify it in a modelling program such as Ray Dream Studio.

The process of modifying an existing model is not strictly a step-by-step process. This tutorial will therefore be presented in the form of a series of pointers.

Importing

The hair models provided with Poser are stored in Wavefront OBJ format, which can be opened by most modelling programs. They are located in the directory 'Runtime:Geometries:hair' in your Poser 3 or 4 installation; the names of the files don't correspond exactly to the names under which they appear in the library listings within Poser, so you may need to open a few files before you find the one you are looking for.

When opening the file, you should generally accept whatever default options are offered to you by your modelling program. With Ray Dream Studio, however, the default settings will result in an almost invisibly small object. A simple solution is to scale the imported object by 5000% immediately after input.

Booleans

If your modelling program supports Boolean operations, you can use these to chop away the parts of the hair that you don't need. The general technique is to create a primitive (typically a cube), align it with the part of the hair model that you want to cut away and then apply a Boolean that subtracts the primitive from the hair model.

A simple Mohawk cut can be produced from the female ponytail model as shown in Figure 1 below, using two cubes to trim away the sides of the hair and a sphere to chop off the ponytail itself.

Figure 1: A simple Mohawk using Booleans

Mesh editing

Most of the work of changing the appearance of the imported hair must be done in a facet modeller such as Ray Dream Studio's Mesh Form Modeller. Here, the object is represented as a set of linked polygons. By moving the corner points of these polygons, you can change the way that the hair looks.

Figure 2: Ray Dream Studio's Mesh Form Modeller

This is a slow and fiddly business. Moving individual points is likely to be too time-consuming to be practical, while moving whole selections can result in unrealistic, blocky shapes. The best tools are generally those which let you move points together, but which vary the amount that points are moved according to their distance from the centre of the selection. Ray Dream Studio's Sphere of Attraction tool is of this kind; when you click on a point and drag, the point and its neighbours all move, but more distant neighbours are moved proportionately less. You probably want to use the Cubic Spline and Bumpy options. Set the tool radius by eye once you've seen how it affects your model.

Figure 3: Example of modified hair model

Unless you're very good with a facet modeller, the results are likely to be somewhat cruder than the professionally-made models that ship with Poser. Nonetheless, they may still provide a useful basis for post-editing.

Deformers

If your modelling program provides tools that deform objects in a specific way, you may be able to use these to generate new hair styles. The image below was produced using the Spikes deformer in Ray Dream Studio.

Figure 4: Spiked hair