HDRI in Unreal Engine

The short answer

Unreal wants one equirectangular HDR, not six faces. Import a 2:1 .hdr and the engine builds a TextureCube asset from it on the spot; the cubemap projection happens inside the importer, never on your desk. From there the same asset feeds three entry points, in rising order of control: the HDRI Backdrop actor for a lit backdrop in one drag, a Sky Light with a specified cubemap for pure image-based lighting, or your own skydome material when the sky needs art direction.

One format note up front: the TextureCube path is built around Radiance .hdr files. An .exr panorama imports as a flat 2D texture instead, usable in a skydome material but not as a Sky Light cubemap. The converter exports Radiance HDR, so the cube path is covered.

Method 1: HDRI Backdrop

The fast path: one actor that provides the visible sky, the lighting, the reflections, and a ground projection.

1. Enable the plugin once per project: Edit > Plugins, search for HDRI Backdrop, check it, restart the editor.
2. Import your 2:1 .hdr panorama. It arrives as a TextureCube.
3. Drag an HDRI Backdrop actor into the level from the Place Actors panel.
4. On the actor, set Cubemap to your texture. Tune Intensity for brightness and Size so the ground projection sits under your scene.

The actor's Projection Center and ground projection keep objects visually anchored to the backdrop, which is the reason to use it over a bare Sky Light for product shots and look-dev scenes.

Method 2: Sky Light with a specified cubemap

When you want the HDRI's light without its picture, because the sky will be replaced or hidden but the ambient should still come from it:

1. Add a Sky Light actor to the level.
2. Set Source Type to SLS Specified Cubemap and assign the imported TextureCube.
3. Leave Real Time Captureoff; that mode captures the scene's sky instead of the specified cubemap.

This is pure image-based lighting: diffuse skylight plus reflections, no visible backdrop. Pair it with a Directional Light rotated to match the HDRI's sun so shadows agree with the brightest spot in the panorama.

Method 3: a skydome material

Full control: a large inverted sphere with an Unlit emissive material sampling the panorama. This is the one route where the flat 2D import (your .exr) is the right input: the material maps view direction to latitude-longitude UVs, so no TextureCube is involved. Disable shadow casting on the dome, push its bounds past the level, and let a Sky Light with Real Time Capture pick the dome up so the lighting follows whatever the material does: tints, sun discs, animated clouds.

Reach for it when the HDRI is a starting point rather than the final sky. For untouched panoramas, the backdrop or Sky Light routes get the same pixels on screen with less to maintain.

Import settings that matter

• Compression Settings: keep the TextureCube on HDR Compressed (BC6H). It preserves float range at a fraction of uncompressed memory; drop to uncompressed HDR only if you see blocking in smooth gradients.
• sRGB stays off for HDR data; float pixels are linear already, and the flag double-darkens them.
• Maximum Texture Sizecaps the cube faces; if a 4K panorama looks soft on the backdrop, the importer's cap is the usual cause.
• Auto-exposure will fight a bright HDRI. Clamp Min/Max EV100in a Post Process Volume (or set the backdrop's Intensity) so the sky holds a stable brightness.

When you'd ever need six faces

In Unreal itself: almost never. The importer builds the cubemap, the renderer projects it, and no workflow hands you six files. The faces matter when the same environment leaves Unreal for an engine that requires them: Source, Roblox, a Quake-derived engine, or raw graphics-API work. That hand-off is what the converter is for, and Cubemap or equirectangular? sorts the full engine list. If your panorama is rendered rather than captured, the Blender guide shows how to produce the equirectangular HDR everything here starts from.