Importing a Scene into Unreal Engine with Datasmith: Scale, Surfaces and Lighting

What you’ll learn in this guide

Datasmith is a feature that transfers data from CAD, BIM and 3D content creation tools into Unreal Engine. However, there’s no guarantee that the imported scene will look identical to the source file in every respect. Scale conversion, object names, surface normals, lightmap UVs and collision can all affect how the scene works in Unreal Editor.

This guide covers common issues that can arise after importing, particularly in architectural visualization and interior projects. The goal isn’t to temporarily mask every problem in the engine, but to identify when it’s better to return to the source scene and make a correction there.

Requirements and version note

Epic’s getting-started guide for developers using custom licenses states that Datasmith is included by default in Unreal Engine 4.24 and later; for older engine versions, the Datasmith plugin must be installed separately. According to the same guide, exporter plugins may also be required for some source applications, such as 3ds Max, SketchUp Pro and Revit. This information applies to the versions covered by that guide; check the current requirements for the engine and source application versions you plan to use.

Installing Unreal Engine through the Epic Games Launcher is described in Epic’s guide as one of the recommended options for custom-license and non-game users. The guide also covers Epic account access and Unreal Developer Network access for teams using custom licenses. First, confirm your organization’s licensing terms and account access. Before performing the checks below after import, you’ll need the source scene and Unreal project ready.

How to check a Datasmith import

1. Verify scale and positions. Distances in Unreal Engine are measured in centimeters. Even if the source application uses a different unit, Datasmith converts the scene’s real-world dimensions and position in 3D space appropriately. The example given is an object modeled at a length of ten units in inches appearing 25.4 world units long in Unreal Engine. After importing, check an object with familiar dimensions and assess the expected conversion before you start rescaling the entire scene by hand.

2. Review object names and hierarchy. Datasmith uses naming information from the source application for the assets and actors it creates wherever possible. However, the static mesh label shown in the Content Browser, the name of the asset file on disk and the actor name in the level don’t have to match. File names must be unique; when actor names conflict, Unreal Engine may create unique names by adding numerical suffixes. If you manage assets with Blueprints or Python scripts, account for the difference between the displayed label and the file name.

3. Check normals on surfaces that appear to be missing. Unreal Engine uses backface culling to avoid drawing triangles facing away from the camera. Some modeling tools show the front and back of a surface in the same way, so single-sided geometry with no thickness may look normal in the source application but disappear from certain angles after import. Move around the model to see whether the surface is visible from another angle. For a surface intended to be seen from only one side, flipping its normal in the source application may be an option. For elements such as walls that need to be visible from both sides, adding thickness to the geometry and directing the normals outward is a more suitable starting point.

4. Choose where to make a lasting fix. You can change the orientation of static mesh triangles or make a material two-sided in Unreal Editor. However, a mesh fix made in the engine may be lost when the Datasmith scene is reimported. A two-sided material isn’t suitable for every problem either: Epic warns that with static or stationary lighting, both sides of a surface may use the same lightmap area, which can produce visual artifacts. An orientation fix in the engine may work for a surface such as a ceiling that’s visible from only one side; for surfaces viewed from both sides, consider correcting the source geometry.

5. Check lightmap UVs and lighting. When using static lighting, each static mesh vertex needs its own UV position in the lightmap. Overlapping triangles in the UV space can prevent lighting and shadow information from being stored correctly. Datasmith automatically unwraps imported static meshes, creating two new UV sets; the second set is configured to store and apply lightmaps. If you see blotches or unexpected lighting after building the lighting, inspect the UV layout and surface orientations together.

6. Set up collision and lighting behavior separately. Datasmith doesn’t create physics settings for static meshes by default. If your project requires physics or collision, configure these in Unreal Editor after importing. Supported light types from the source application can be converted, but some area, plane or volume lights have no exact equivalent in Unreal Engine, so their behavior may need to be approximated using a custom Blueprint approach. Check the result separately in the intended scene and lighting setup.

Common mistakes

Assuming part of the model wasn’t imported: The surface may be facing away from the camera. First inspect it from a different angle, then check its normals and whether it’s single-sided.

Fixing everything with two-sided materials: This can make surfaces visible from both directions, but may cause lightmap-related artifacts with static or stationary lighting. Correcting the source geometry’s thickness and normals may be a more lasting approach.

Assuming an in-engine fix will survive reimport: Changes to triangle orientation made in the Static Mesh Editor may be lost when the Datasmith scene is reimported. If the source scene will be edited again, make the correction there too.

Assuming every imported mesh is ready for collision: According to the source, Datasmith doesn’t configure physics for static meshes by default. Account for collision requirements separately in your ongoing project workflow.

Impact on architectural and visualization workflows

For teams bringing architectural models into interactive presentations, correct scale conversion can reduce the need to resize the scene from scratch, but it doesn’t eliminate the need to check dimensions, surface orientation and lighting behavior after import. Interior walls, ceilings and thin surfaces visible from both sides need particular attention when checking normals. In scenes using static lighting, it’s important to consider UV overlaps and two-sided material decisions together.

Offices and students can aim to maintain an organized hierarchy in the source file and decide in advance which fixes belong in the source model and which should be made in Unreal Engine. Teams managing many assets with scripts should watch for differences between names, labels and file names. Exporter requirements for the versions in use, licensing terms and whether the computer is suitable for the project should also be part of the import plan. Since the sources don’t specify a hardware threshold, no definitive hardware recommendation can be made here.

Next steps

Start by testing the import with a small, representative section of the scene. If the scale and object names look right, check single-sided surfaces from different angles; if you’re using lightmaps, review the UVs. Finally, determine whether collision and lights need additional configuration for the intended use. These checks can help reduce the risk of having to fix the same issue across many assets in a large scene.

Sources and licensing

This guide is based on information in Epic Games’ Unreal Engine documentation about the Datasmith import process and its getting-started guide for users with custom licenses. These pages are marked “free” in the source records. The content has been reorganized and adapted in Turkish.