Unreal Engine Material Instances: An Archviz Guide

In Unreal Engine, master materials and material instances can be used to create different color, roughness and texture options from the same surface foundation in architectural visualization scenes. Epic’s documentation focuses on parameterizing the properties to be changed in advance, rather than rebuilding the material for every variation. The steps below bring together workflows from the Material Instances documentation and the Material Parameter Collection and Archviz Interior Rendering documents published for UE 4.27.

1. First, decide which properties will change in the master material

A master material is the base graph inherited by child material instances. When an instance is created, it takes the appearance and properties of its parent material as its starting point. However, not every property is automatically editable: values to be changed in an instance must be defined as parameters in the master material.

In architectural scenes, properties such as Base Color, Metallic and Roughness can be used for different surface variations. Epic’s interior example uses a Texture Parameter to change a texture, a Vector4 Parameter to add a tint to a texture, and a Switch Parameter for options. Rather than exposing everything, selecting the properties artists and designers are actually expected to change makes the master material more useful.

Give parameters clear, unique names. For example, the documentation uses a default value of 0.25 for a Roughness Scalar Parameter. Values intended to remain fixed do not appear in the instance editor if they are not made into parameters, allowing teams to distinguish between properties that can be changed and those that should remain unchanged.

2. Create a material instance and edit its variations

1. Prepare a suitable master material and define the values you want to change as parameters. A Scalar Parameter holds a single floating-point value and can be used for individual controls such as Roughness and Metallic. A Vector Parameter contains four channels and can manage multi-component values such as color. A Texture Parameter lets you change the texture used in the instance.

2. In the Content Browser, right-click the material asset and select Create Material Instance. In the material instance that opens, the properties inherited from the master material and made editable appear under Parameter Groups in the right panel.

3. Create color, texture or roughness variations on the instances. Epic’s Archviz example demonstrates changing a tint with material instances and replacing a diffuse or normal texture with another texture. This makes it possible to create variations from the same parent structure rather than setting up a separate base material for every object.

4. Check that the changes appear in the main viewport. According to the documentation, parameter changes in material instances can be seen quickly without recompiling the standard material graph. Recompiling a standard material can take up to a minute, depending on its complexity; this is not a fixed performance guarantee for every project.

3. Manage shared values with a Material Parameter Collection

If the same value needs to be changed across many materials, you can use a Material Parameter Collection (MPC). This asset stores scalar and vector parameters; materials can reference the same collection to use shared values. Epic describes this method as an alternative to updating values such as wetness, snow or destruction amount individually in separate material instances across a level.

To create a collection, right-click in the Content Browser and select Material Parameter Collection under Materials & Textures. Open the collection and add a new value using the add control next to the Scalar Parameters or Vector Parameters heading, then enter a name and default value. To use the collection in a material graph, add the relevant collection to the graph and connect a Material Collection Parameter node to the appropriate material input. In the example in the documentation, Global_Desaturation feeds the Fraction input of a Desaturation node.

Keep the limits in the UE 4.27 documentation in mind: a material can reference up to two different Material Parameter Collections, and each collection can contain up to 1024 scalar and 1024 vector parameters. Changing the number of parameters in a collection causes materials that reference it to recompile. For this reason, it may be preferable to plan the parameters in advance if many values are expected to be added.

Collection values can also be changed at runtime with Blueprint. In the documented example, the Set Scalar Parameter Value node takes a collection and parameter name; a Timeline moves the value from 0 to 1 and back again. Renaming a parameter in a collection can preserve material connections, but the parameter name must be reassigned in any Blueprint function that uses it.

4. Where does this fit into an architectural visualization workflow?

If an apartment, office or residential scene needs multiple color options for the same wood, fabric or painted surface, material instances make those variations easier to manage. A shared master material keeps consistent properties centralized, while instances allow changes to be made for specific objects or design options. An MPC can also be used for shared scene values that affect multiple materials.

Epic’s Archviz Interior Rendering example demonstrates physically based materials, master materials and instances, dynamic lighting and ray tracing techniques in UE 4. This does not mean that every visualization project should use the same lighting setup; it simply shows that material instances can be part of a broader interior workflow. In scenes using ray tracing in particular, reflection quality and performance should be evaluated together. Hardware requirements and licensing terms are not specified in these documents, so they should be verified separately for the project environment.

Common mistakes

• Trying to change a value in a material instance that has not been parameterized in the master material. First check that the relevant property is defined as a parameter in the master graph.

• Creating a separate master material for every object. If objects share similar properties, a common master material and instances can provide a more efficient setup.

• Not checking Blueprint connections after renaming an MPC parameter. The Parameter Name field in any Blueprint function that uses the name must be reassigned.

• Using too many Static Parameters. Static parameter combinations can lead to separate material compilations; Epic recommends limiting their use and the combinations they create.