Tutorial: Creating PBR materials

In this tutorial, we will walk you through the PBR material models in Light Tracer Render.

Light Tracer Render provides three PBR material models: Principled, Glass, and Shadow Catcher. You can switch between them on the Properties tab.

Light Tracer Render's user interface showing the three PBR material models

Each model contributes to the creation of impressive visuals for your projects. In this tutorial, we will discuss these models in detail, equipping you with the understanding and skills to make the most of Light Tracer's capabilities. Let's get started and explore the potential of these material models together.

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Principled material

Get ready to explore the Principled material! This versatile, multi-layer model simplifies your life by merging everything into one easy-to-use shader. Inspired by Disney's principled model, also referred to as the "PBR" shader, it ensures compatibility with software such as Pixar's Renderman® and Unreal Engine®. Plus, you can effortlessly drag and drop image textures created or baked with software like Substance Painter® into the relevant texture slots.

This "all-in-one" shader allows you to create a wide variety of materials. The base layer offers a user-controlled blending of Diffuse, Metallic, Specular, Sheen, and Transparency. Furthermore, you can enhance your material with additional Clearcoat and Iridescence layers. All of these settings can be configured on the Properties tab.

Principled material properties tab in Light Tracer Render

There are very few basic parameters. As for advanced ones, they are grouped into a collapsed region that can be expanded using a horizontal arrow-button.

Base layer properties

Base Color

The very first setting is responsible for the color of diffuse or metallic surfaces.


Transitions between non-metallic (or dielectric) and metallic material models. At 1.0, the material is fully metallic that has no diffuse component and has a tinted incident specular, equal to the base color. At 0.0, the material consists of a pure diffuse base layer, topped with a dielectric specular reflection layer.

Metalness parameter, material change, PBR

Increasing Metalness from 0.0 to 1.0


Determines microfacet surface roughness for diffuse and specular reflection (we use GGX microfacet distribution which is one of the most widely used in the rendering industry).

Roughness parameter, diffuse, specular reflection

Increasing Roughness from 0.0 to 1.0. Top row: 0.0 metalness, bottom row: 1.0 metalness

Advanced Base layer properties


Blends between a completely opaque surface at 0.0 and fully transparent at 1.0. This simple transparency does not model light refraction but is very useful in practice for modeling decals, foliage, vegetation, and thin (architectural) glass. To make architectural glass look realistic, such material must also be covered with a layer of varnish so that it reflects part of the light (or just use Thin glass preset from the Library).

Transparency Tint

Blends between white and base color for transparency. Useful for stained glass windows.

Transparency, Tint, stained glass effect, PBR

Top row: increasing Transparency from 0.0 to 1.0. Bottom row: increasing Tint from 0.0 to 1.0 with constant transparency

Fabric sheen

Produces soft, velvety reflection near edges, ideal for simulating materials like fabric.

Fabric Sheen, velvet reflection

Increasing Fabric Sheen from 0.0 to 1.0

Sheen Tint

Blends between white and base color for sheen reflection.


Controls the amount of dielectric specular reflection. For example, for typical window glass Reflectance is ~0.5, while for a diamond it is ~2.2.

Reflectance, dielectric specular reflection

Increasing Reflectance from 0.0 to 3.0

Reflectance Tint

Blends between white and base color for dielectric specular reflection color.


Sets degree of anisotropy for specular reflection, both metallic and dielectric. Higher values result in elongated highlights along the tangent direction.

Anisotropy parameter, specular reflection, elongated highlights

Increasing Anisotropy from 0.0 to 1.0

Anisotropic Rotation

Alters the anisotropy direction.


Provides a flatter appearance and serves as a quick approximation for subsurface scattering.

Flatness parameter, subsurface scattering approximation

Increasing Flatness from 0.0 to 1.0

Coat layer

Additional white specular layer above base layer, suitable for materials such as wood finish, car paint or thin/arcitectural glass (with transparent base).

Coating Color

Absorption color of the coating.


Controls the amount of visible coat by adjusting its index of refraction (IOR) from 1.0 to 3.0.

Clearcoat parameter, coat layer, white specular

Increasing Clearcoat from 0.0 to 1.0


Thickness of coating layer affecting absorption strength.

Thickness parameter, coating layer absorption strength

Increasing Thickness from 0.0 to 1.0


Surface roughness for coating layer.

Roughness parameter, coating layer surface roughness

Increasing Roughness from 0.0 to 1.0


In rendering, material emission makes objects glow like light sources. This helps make your scene look more real and sets the mood. Emission lights up other objects and can even speed up rendering. To make a material emit light, adjust the settings in Emission group. Experiment with different colors and brightness to create the perfect atmosphere for your scene.

Emission Radiance parameter, glowing material

Increasing emission Radiance parameter

Emission Color

Emission light color.


Intensity of emitted light.


Light Tracer Render models iridescence caused by thin film interference. This interaction between the light waves causes the colorful patterns you see in soap bubbles or oil slicks, as different wavelengths of light (colors) interfere with each other in various ways. Look for presets in the material Library for realistic combinations of parameters.

Thin-film width and index, iridescence, light interference

Top row: changing Thin-film width; bottom row: changing Thin-film index

Thin-film width

Thicker films tend to produce color shifts toward longer wavelengths: red, orange, and yellow, while thinner films toward shorter ones: blue, green, and violet.

Thin-film index

When light passes through a thin film with a higher refractive index, it bends more than it would in a film with a lower refractive index leading to variations in the iridescence pattern and the colors observed.

Glass material

Glass material allows objects to refract incoming light. It helps in modeling realistic liquids, glass and gemstones. The glass material can cause additional noise due to caustics. Read more about caustics rendering in this tutorial.


Material index of refraction. Affects how much the object will bend the light. Real world dielectric materials have various refractive index: air – 1.0, water – 1.33, glass – 1.5, diamond – 2.42.

IOR parameter, light refraction, glass material

Increasing IOR from 0.0 to 1.0


Amount of dispersion. Light dispersion happens when white light passes through something, like a prism or raindrop, and breaks into different colors. In 3D rendering and photography, light dispersion helps create realistic and nice-looking effects, such as colorful patterns in scenes with glass or gemstones. Light Tracer Render uses Cauchy equation to set dispersive properties of material conveniently, so the Dispersion value corresponds to Cauchy B coefficient. Sample values for commonly used materials are: water – 0.0005, glass – 0.004, sapphire – 0.014, diamond – 0.01.

Dispersion parameter, light dispersion, Cauchy B coefficient

Increasing Dispersion from 0.0 to 1.0


Roughness of the surface.

Roughness parameter, glass surface roughness

Increasing Roughness from 0.0 to 1.0

Advanced Glass properties

Glass tint color

Color to modulate the reflected or transmitted light.

Reflection tint

Blends between white and tint color for reflected light.

Refraction tint

Blends between white and tint color for transmitted light.


Light attenuation is the reduction of light intensity as it passes through a medium, such as air, water, or glass. The intensity of light decreases exponentially with the distance traveled through the medium. The rate of decrease depends on the medium's absorption coefficient. In rendering, light attenuation is crucial for accurately simulating light behavior in various environments, especially with transparent materials or underwater scenes.

Absorption color and Density, light attenuation

Objects of different size with the same Absorption color and Density

Absorption color

Remaining color after traveling through the object volume.


Amount of absorption in object volume.

Increasing absorption density

Increasing absorption Density


Thin film layer properties are the same as for the Principled model.

Catcher material

Catcher material is a special non-physical material type made for easier composition with scene background. There are two types of catcher material: Shadow catcher and Glossy catcher.

Shadow catcher and Glossy catcher materials

Shadow catcher

When rendering, the shadow catcher material only collects the shadows projected onto it, while the catcher object itself remains transparent. This feature allows artists and designers to easily composite rendered objects onto backgrounds or images, while preserving the realistic shadows cast by the objects. Shadow catcher materials are commonly used in visual effects, architectural visualization, and product design to seamlessly integrate 3D elements into real-world environments or photographs.

Shadow catcher material, realistic shadows

Glossy catcher

Glossy catcher material, metallic reflections

The Glossy catcher functions similarly to the shadow catcher material, but instead of capturing shadows, it collects reflections from scene objects as if it was a metallic surface, all while seamlessly blending with the background.


Surface roughness for reflections.

Edge fade

Increases transparency of the catching surface near the edges.

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