Create Non-Interactive Hair Mapping Using XGEN | Maya Tutorial

When creating animal hair with XGEN, if we want to use a mapping to make the color of the animal hair, it is very easy to achieve with interactive hair. But once we use non-interactive hairs it's a bit more of a toss-up. In this article, the leading cloud rendering service provider and render farm in the CG industry, Fox Renderfarm will share with you how to use a mapping to generate hair color under non-interactive conditions.

Process and Effect

Create a face slice and make sure it has UV.

Create a Groom spline.

Simply adjust some parameters and update the hairs.

Find the Primitive Color under Preview/Output, click the down arrow and appears Create Map, name the Map fur_color, and adjust the Map Resolution (slightly larger value).

Once created, click the Brush button to draw a few random strokes on it, then click the Save button.

This gives us a new lambert material sphere in Hypershade with the saved mapping we drew automatically attached to it.

Click on the folder icon to add a color map for the hair color. It is better to use Xgen with a project directory, many hair mapping textures need to be saved in it.

To demonstrate that the hairs are more visible, I use a map with a sharp color distinction.

Save again, pay special attention to remember to click save diligently. After updating the hair you can see that the hair has changed color (it does not matter if the color has not changed in the view at this time). But the rendering is definitely wrong at this point. Let's continue to the next step.

Move down to the Custom Shader Parameters column, replace the float in the Name property with color, and click the "+", then give the name shade_color (the name here depends on your personal needs). After that, a new column of color shade_color interface will be generated.

Then go back to the Primitive Color property bar and click the last button to open the expression editor and copy these two lines of expressions.

Go to the color shade_color property bar again to open the expression editor and paste these two lines of expressions. And click Apply and Accept.

Again, remember to click the Save button when you are done.

Next, create an aiStandardHair in the HyperShade interface and adjust Melanin to 0.

An important step is to create an aiUserDataColor node and copy and paste the name of shade_color into its Attribute column. After that, connect this node Out Color to the Base Color in ai StandardHair.

We can first create an aiSkyDomeLight to give an HDR rendering to test it.

You will find that the colors are not rendered.

Because we need to assign aiStandHair material to description9.

By default Xgen is using the hairPhysicalShader.

You can see that the colors are displayed properly. But there seems to be some incorrect colors. It is grayish.

Back in Preview/Output, add a line of gamma to the expressions of Primitive Color and color shade_color for correction.

Second line of the full expression: "$a->gamma(0.454)".

After calibrating the colors, I switched the lighting to aiPhysicalSky for accurate rendering ( I didn't find a particularly good HDR image). This way the Xgen non-interactive hairs use the color of the mapping.

Author: JI WEI