Softimage - Rendering hair and fur

Maxwell Render supports Softimage hair starting with version 2.6, and will render the hairs with its own cone shaped parametric hair primitive. This saves a lot of time when exporting the scene and also RAM when rendering - compared to converting the hairs into polygons. The cone shaped hair primitive in Maxwell has actual thickness so any Maxwell material can be applied to it - including transparent ones - and the hair fibers will refract the light correctly.

Softimage Hair parameters

Since Maxwell supports most of the SI hair parameters, here is a list of parameters that are irrelevant or not supported when rendering the hair with Maxwell:

• Hair Geometry (Maximum depth, Maximum Size)
• Hair instancing

Mapping the hair

Maxwell Render uses two UV channels to map the hair along the hair fiber and also map the root UVs. The UV channels used are 0 (root to tip) and 1 (root UVs). By default the generated hair already has root to tip UVs so if you only want to use a texture along the hair fiber, but not across the surface of the hair, you can simply apply a Maxwell material to the hair and attach a texture to any of the texturable input ports (most likely the reflectance 0 port of the BSDF node). If you wish to also use mapping across the surface you must first transfer the UV map of the generating hair mesh to the hair, using the Transfer Map option in the SI hair menu.

The following steps describe different mapping options:

Step 1 - Applying a default Maxwell Layered material to the hair

Apply a Maxwell material to the hair. The following image shows a default grey material.

Step 2 - Applying a texture along the hair fibers

Using a MaxwellTexture node, apply a texture to the reflectance 0 port of the BSDF. Open the MaxwellTexture PPG and set the Channel Type to "Use Index" and set the Channel Index to 0. The texture (in this case a dark to light green gradient) is applied along the hair fibers.

Step 3 - Transferring the UV map of the generating mesh to the hair

In order to use a second texture, mapping the Channel Index 1, we need to first transfer the UV map of the generating mesh to the hair. With the hair selected, click the Transfer Map button in the SI hair menu (Ctrl+2 to make it visible), and then click on the Texture projection of the generating mesh (in an Explorer window).

Now that the UVs have been transferred to the hair, you can apply a texture which will be mapped across the surface of the hair. Apply the texture as before to the material, only this time change the Channel Index in the MaxwellTexture node from 0 to 1. This will tell Maxwell to user the second UV channel that's now attached to the hair.

Mapping both UV channels in the same material

It is also possible to map several textures at the same time and controlling if they should be applied on the length of the fiber or across the surface simply by setting the Channel Index each texture should use. A common approach is to use two layers, each with one BSDF and their own textures, and a third texture used as a layer mask. This way you have very good control over exactly where each map appears.

A two layer material. The top layer uses a gradient as a Layer mask to hide parts of the top Layer. Click image to enlarge

The example above shows a gradient black and white texture used as a layer mask for the layer that is on top. Any areas that are white will reveal the BSDF(s) in this layer. For more information on working with Layers see the Stacking Layers page in the Maxwell documentation.