Export procedural buildings to Unreal Engine.

Freeze the useful source state

Save the complete Metropolygonia preset and seed before download. The exported mesh is a snapshot; the preset is what makes the design meaningfully editable. If a later review changes floor count, façade rhythm or interior scope, correct the source parameters and export again.

• Give the project and building a stable, descriptive name.
• Check whether interior rooms, partitions, slabs and stairs are actually required.
• Orbit the model and inspect section or geometry views for intersections and missing surfaces.
• Identify a known dimension that can be measured after import.
• Choose GLB unless a downstream requirement specifically calls for glTF, OBJ or STL.

Import a GLB through Interchange

1. Export the building as GLB

   The file contains the glTF scene and binary geometry together, and can embed the generated image textures. Keeping the handoff self-contained reduces missing-resource errors.

2. Use Unreal Engine's current import path

   Bring the file into the Content Browser through the current Interchange-based workflow. Epic changes options between releases, so use the documentation for the Unreal version in your project rather than copying an old preset blindly.

3. Start at scale 1.0

   Metropolygonia stores model dimensions in metres and the city manifest declares metres. Import at 1.0 first, then measure the known doorway, storey or footprint dimension.

4. Keep semantic parts when useful

   Avoid combining every imported static mesh automatically when separate generated parts or material assignments matter to your editing and optimisation plan.

5. Inspect before placing instances

   Check normals, pivots, openings, interior circulation, UVs and material-slot names. Fix source or import problems before duplicating the asset across a level.

Refer to Epic's official pages for Interchange asset import and glTF support when checking current version-specific behaviour.

Understand the ZIP before importing it

The Unreal city package is organised for asset-level control. It is not simply one merged city mesh. The current archive contains:

• buildings/SM_###_name.glb — one GLB for each placed building, reset to a local origin for independent use.
• roads/SM_City_RoadNetwork.glb — the generated road network when the project contains roads.
• manifest.metropolygonia-city.json — project units, importer guidance and each building's location, Y rotation and scale.
• README_UE.txt — a compact package-specific import reminder.

The road network retains the city project's world coordinates. Buildings use local pivots and their placement transforms are recorded in the manifest. Preserve that distinction if you reconstruct the layout programmatically or by hand.

A five-part acceptance check

1. Scale

Measure the known reference and compare it with the intended metric value. Also compare door and storey proportions against an Unreal mannequin or other trusted reference.

2. Geometry

Look for flipped normals, open seams, coplanar flicker, intersecting access elements and missing section surfaces. Review interiors from inside, not only through an exterior orbit.

3. Materials and textures

Confirm material slots remain distinguishable and expected image textures arrived. A successful preview is not yet a final PBR shader; author or replace production materials in Unreal Engine.

4. UVs

Apply a tiled checker to several differently sized elements. At multiplier 1, the intended base convention is one repeat per 2 × 2 metres. Adjust the Unreal material tiling for the selected library and art direction.

5. Runtime requirements

Decide collision, LOD or Nanite strategy, lightmap handling, instancing and streaming from the actual target platform and camera distance. The generator cannot infer those project constraints.

Use the current handoff honestly

GLB and glTF can carry named materials and embedded or referenced image data; the Metropolygonia exporter waits for pending texture work before creating a model. OBJ uses MTL plus PNG sidecar files, and STL contains geometry only.

Native PBR material export is still in progress and coming soon. Today, rely on material grouping, available image textures and UV coordinates, then build the final physically based material graph in Unreal Engine. This gives the production team control over normal intensity, packed channels, surface variation and platform-specific shader cost.

Continue with the 2 × 2 m UV guide for a tiled-material setup, or compare the full handoff boundaries in the export format reference.