Overview

The HumanSkin shader is a specialized shader for rendering skin surfaces as skin shading cannot be accurately reproduced using regular lighting models.

Shader Params

Shader Params

Description

Shader gen option

Detail bump scale

Controls the strength of the detail normal map (default 0.5)

Detail normal map

Displacement bias

See Tessellation and Displacement for more information.

Displacement Mapping

Displacement height scale

See Tessellation and Displacement for more information.

Displacement Mapping

Indirect bounce color

See Illum Shader for more information.

All

Melanin

Legacy feature. Controls the amount of pigmentation in the skin (default 0.0)

All

SSS Index

Functionally obsolete. The skin shader is locked to the skin SSS range (1.001 to 1.999) by default

All

Tessellation face cull

See Tessellation and Displacement for more information.

Displacement Mapping

Tessellation factor

See Tessellation and Displacement for more information.

Displacement Mapping

Tessellation factor max

See Tessellation and Displacement for more information.

Displacement Mapping

Tessellation factor min

See Tessellation and Displacement for more information.

Displacement Mapping

Translucency Multiplier

Controls strength of the SSS feature (default 0.7)

All

Wrinkles blend

Controls strength of the wrinkle map (default 1.0)

Wrinkle blending

Using the HumanSkin shader

This new version of the HumanSkin shader is fully integrated with the Physically Based Shading model. From a user standpoint, the shader has been streamlined - most tweaking takes place directly via the individual texture maps, with individual attributes of the shader being locked to the physically correct values. This enhances usability and insures consistency between assets. HumanSkin features some unique texture slots to give artists control over the specific features of the shader.

Diffuse

Its generally advisable to author 'flat' diffuse maps. I.e. when basing textures off photographs or scan information, its key to remove most lighting information. When hand-painting diffuse maps, the focus should be on color and hue changes. An exception to this is high-frequency Ambient Occlusion/Cavity information, which can be added to fake detail occlusion and shading.

Specular Map

In order to achieve a physically correct representation of human skin in the PBR model, a flat base-value of 51 should be used for the specular map. Adding subtle pore detail on top of that (simulating high frequency occlusion) will generally give the most convincing results. Also, to compensate for precision issues with occlusion and shadow casting, it can be helpful to paint in/darken details such as nostrils, cavities of the ear, etc.

Bumpmap (Normalmap)

For best results, it is advisable to experiment with the strength of high-frequency details on the highpoly source asset – i.e. keeping such details on separate layer(s) in the digital sculpting app, can be helpful.

Gloss (Normalmap Alpha)

On the large scale, the gloss map should capture how oily/shiny certain areas of e.g. a face are. This  Adding high contrast details will help to break up specular highlights and improve the look.

Detail

The selected map will be overlayed with the base normalmap – an easy way to add very high-frequency detail to a model and further break up specular highlights. Tiling can be controlled in the tiling subsection of the texture slot.

Detail normal map must be turned on in ‘Shader Generation Params’

Opacity Map (SubSurfaceScattering)

The SSS map should represent thin areas of skin that can readily be penetrated by light (e.g. ears, nostrils, etc.). SSS maps can be either manually authored or baked with an appropriate tool (e.g. with version 3.18.6, xNormal introduced a feature to bake translucency maps)

Decal

Will overlay a secondary diffuse map (requires an alpha channel). This is useful to create variation of existing textures, e.g. add tattoos, warpaint or dirt.

Decal Map must be turned on in ‘Shader Generation Params’

预览

人体皮肤着色器是一个专门渲染皮肤表面的皮肤着色技术,作为皮肤着色不能准确地复制使用正常的光照模型

着色器属性

Shader Params

Description

Shader gen option

Detail bump scale

 控制detail map的强度(默认0.5)

Detail normal map

Displacement bias

查看 Tessellation and Displacement 获得更多信息.

Displacement Mapping

Displacement height scale

查看 Tessellation and Displacement 获得更多信息.

Displacement Mapping

Indirect bounce color

查看Illum Shader 获得更多信息.

All

Melanin

肤色特征. 控制皮肤中的黑色素的量 (default 0.0)

All

SSS Index

Functionally obsolete. The skin shader is locked to the skin SSS range (1.001 to 1.999) by default

All

Tessellation face cull

查看 Tessellation and Displacement 获得更多信息.

Displacement Mapping

Tessellation factor

查看 Tessellation and Displacement 获得更多信息.

Displacement Mapping

Tessellation factor max

查看 Tessellation and Displacement 获得更多信息.

Displacement Mapping

Tessellation factor min

查看 Tessellation and Displacement 获得更多信息.

Displacement Mapping

Translucency Multiplier

控制次表面散射功能的力度(默认0.7)

All

Wrinkles blend

控制皱纹贴图的力度(默认为1.0)

皱纹融合

使用人类皮肤着色器

新版本的HumanSkin shader 是完全基于基于物理技术渲染的模式。从用户的角度上看,新的HumanSkin shader 已经非常的简化了,多数的是通过放置贴图纹理来实现,一部分的属性是一些固定的物理参数。这增加了美术资源之间的可用性和一致性。HumanSkin shader 为美术工作者提供了一些特殊的贴图插槽来实现控制shader的特殊功能.

Diffuse

我们这里建议制作者制作比较平的diffuse 贴图。例如你贴图是通过照片或扫描获得的,这需要清除贴图上的大部分的光照信息。一旦你开始绘制diffuse 贴图,你需要将工作重心放置在绘制贴图的颜色和色调变化上。但是关于Ambient Occlusion可以是例外,这种情况可以增加一个假的occlusion 或阴影来增加细节。

Specular Map

为了实现PBS渲染模式使用人类皮肤的物理上正确描述,制作一套平的颜色数值在51的高光贴图是必须的。可以增加一些毛孔胡须的细节在上面(模拟高频的occlusion)这样通常会有最准确的数值

同时为了弥补occlusion 阴影的精度问题它可以帮助绘制/暗部的细节如鼻孔耳朵的空腔等。

Bumpmap (Normalmap)

为了获得最佳效果,最好是在源高模上进行调整normalmap 的细节力度,例如在雕刻软件中分层保留这样的细节信息,这将会非常有用。

Gloss (Normalmap Alpha)

光泽度贴图应该表现某些区域有多光滑,例如脸部区域。增加这个贴图的原因就是为了区别一些区域的变化使得区域内的光泽度产生变化,例如毛孔区域内的光泽度肯定没有皮肤周围光滑。

Detail

选择的贴图会叠加到基础的normal map 上面,这是一个非常简单增加细节分辨率的方法,同时还可以让高光看起来更加凌乱和自然。重复次数可以在贴图下面进行控制。

请打开 ‘Shader Generation Params’ 下面的Detail Normal map 并开启

Opacity Map (SubSurfaceScattering)

SubSurfaceScattering贴图必须应用在皮肤比较薄的地方,因为这些地方透光性好(例如耳朵,鼻子等等),你可以找一些工具来制作SubSurfaceScattering贴图(例如xNormal 3.18.6,里面包含了一个特殊的烘焙 translucency 贴图的工具)

Decal

decal 贴图就是第二diffuse 贴图,这个功能非常有用的功能用于变换现有的纹理,例如增加纹身,迷彩伪装,或污垢脏迹等等

必须打开 ‘Shader Generation Params’下的Decal Map才有效