Using Datasmith with Rhino

Describes special considerations that apply when you use Datasmith to import scenes from McNeel Rhinoceros 3D.

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This page describes how Datasmith imports scenes from McNeel Rhinoceros (Rhino) into Unreal Engine. It follows the basic process outlined in the Datasmith Overview and About the Datasmith Import Process, but adds some special translation behavior that is specific to Rhino. If you're planning to use Datasmith to import scenes from Rhino into Unreal Editor, reading this page can help you understand how your scene is translated, and how you can work with the results in Unreal Editor.

Rhino Workflow

Datasmith uses an export workflow for Rhino. This means that to get your Rhino content into Unreal using Datasmith, you need to:

  1. Install the Datasmith Exporter plugin for Rhino. See Installing the Datasmith Exporter for Rhino.

  2. Export your Rhino content using the Save As or Export process. See Exporting Datasmith Content from Rhino.

  3. use the Datasmith importer available in the Toolbar of the Unreal Editor to import your .udatasmith file. See Importing Datasmith Content into Unreal Engine 4.

To read more about other types of Datasmith workflows, see Datasmith Supported Software and File Types.

Converting Geometry into Static Meshes

Datasmith creates a separate Static Mesh Asset for each separate mesh, solid, or surface in the Rhino file. If the object has its Name property set in the Properties panel in Rhino (shown on the left in the image below), Datasmith uses that name for the Static Mesh Asset (shown on the right in the image below). Any Actors that Datasmith creates in your Level that refer to that Static Mesh Asset also use the same name.

Instancing

When Datasmith detects multiple instances of the same block in your Rhino scene, it only creates one set of Static Mesh Assets for the geometry in that block. It then places multiple instances of those Static Meshes into the scene. This is typically better for the runtime memory requirements and performance of your Project. It also makes it easier to manage the number of Static Meshes in your Content Browser.

Wherever possible, we recommend taking advantage of this by making any repeating elements in your scene (such as windows, doors, or chairs) into blocks in Rhino.

For details, see the Rhino documentation.

Tessellation and Render Meshes

Unreal Engine always renders objects using triangular meshes. If you have objects in your Rhino file that are defined as parametric surfaces, or NURBS, these surfaces need to be transformed, or tessellated, into triangular meshes. Datasmith will utilize the Rhino tessellation options located in File > Properties... > Document Properties | Mesh:

Name

Description

Jagged and Faster

Creates a lower density mesh to shade objects quickly at the cost of some quality.

Smoother and Slower

Creates a higher density mesh to shade objects more accurately at the cost of speed.

Custom

Allows for greater control over the mesh created. The density slider roughly controls the density and number of polygons created from NURBS surfaces. Additional controls are available by clicking the Detailed controls... button.

For more information on using custom render options in Rhino, see Polygon Mesh Detailed Options in the Rhino documentation

Triangle Facing Direction

The surface maintains orientation when exporting to Datasmith. A way to visualize surface orientation within Rhino is to set the colors of backfaces to a bright green color. Do this by opening the Document Properties and heading to View > Display Modes > Rendered. In that menu, find the Shading Settings and look at the Backface options. Finally, change the Single color for all backfaces color to bright green:

This way you can check before exporting to Datasmith whether or not faces orient correctly:

backward-facing

forward-facing

For a complete discussion and recommended solutions, see About the Datasmith Import Process.

Rhino Materials

For each different surface material that Datasmith finds in your Rhino scene, it creates a separate Material Asset in Unreal with the same name. Each Material is then placed in the Materials folder next to your Datasmith Scene Asset.

  • Each Material in the Materials folder is a Material Instance that exposes properties set in the Rhino file: color values, texture maps, and so on. You can change these exposed properties to modify the way the Material looks when applied to a surface. Datasmith assigns these Material Assets to the Static Mesh Assets it creates to shade their surfaces the same way they appear in your Rhino renders.

    Datasmith only imports materials from Rhino objects into the Unreal Engine. It ignores Rhino display colors completely. This makes the visual result of your import into the Unreal Engine match the result of rendering in Rhino as closely as possible.

  • Datasmith also creates a set of parent Materials in the Materials/Master folder. Each of these is the parent of at least one of the Material Assets in the Materials folder. You can edit these parent Materials if you want greater control over the Material graphs that define how each surface appears, expose additional parameters to child instances, or change the way the exposed parameters are taken into account during rendering.

    Note that changing a parent Material also changes all Material Instances that inherit from that parent automatically. It's usually a good idea to duplicate a parent Material before you modify it, then make your changes to the duplicate, then finally update specific Material Instances to use your new duplicate as their parent. For details, see Modifying a Datasmith Master Material.

Rhino Metadata

Data input in the Attribute User Text menu exports as Datasmith Metadata:

Data is entered into the table as a key value pair. For more information on using Attribute User Text, see Attribute User Text in the Rhino documentation

Building the Datasmith Scene Hierarchy

Datasmith builds its scene hierarchy from your Rhino model as follows:

  • For each layer in your Rhino scene, Datasmith creates an Actor in Unreal to act as the parent for all objects on that layer. Note that unlike the layers it creates in the Layers panel of the Unreal Editor, this hierarchy of Actors is not flattened. The Actors are nested exactly like the layers in your Rhino scene.

  • Under the Actor that represents each layer, every instanced block on the corresponding layer is represented by another Actor.

  • Finally, the Actor that represents each layer and each block contains Static Mesh Actors that represent the actual geometry objects that make up that layer or block. Points in Rhino are represented as empty Actors in Unreal Engine. This preserves the points as

  • Groups in Rhino do not affect the Unreal scene hierarchy, as they are considered selection helpers rather than important elements in the scene hierarchy.

For example, in the image below, you can see that every layer in the Rhino hierarchy has a counterpart Actor in Unreal. Layers like lights > turn signals, which contain only geometry objects in Rhino, contain only the corresponding Static Mesh Actors in Unreal. The lights layer in Rhino also contains two block instances, named left_headlight and right_headlight. Each of these is represented by a nested Actor in Unreal, which in turn contains the geometry objects that make up those blocks.

Credit: The model used on this page is courtesy of Turbosquid user tomashorin.design.

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