How to Generate a Skybox for Unity

Last updated 2026-07-08

To generate a skybox for Unity: create a seamless 2:1 equirectangular image with an AI skybox generator such as Atmos Forge, repair the wrap seam, export a PNG, import it into Unity with Texture Shape 2D and Wrap Mode Clamp, assign it to a Skybox/Panoramic material, and set that material in Lighting → Environment.

Unity accepts three skybox forms: panoramic (equirectangular), cubemap, and six-sided — panoramic is the simplest single-file path.
Wrap Mode must be Clamp and mip maps disabled, or the wrap edges bleed into a visible vertical seam.
HDR lighting: Unity imports .hdr files natively for environment lighting.

Step 1: Generate the equirectangular panorama

In Atmos Forge, describe the sky in a text prompt — scene, time of day, weather, style — and pick a style/mood preset. The generator renders a seamless 2:1 equirectangular image and previews it on an interactive 3D sphere so you can check the horizon and poles before continuing.

Step 2: Fix the wrap seam

The left and right edges of the panorama meet behind the camera in Unity. Run the free Fix Seam tool to blend the wrap edges; skipping this is the most common cause of a visible vertical line in the sky.

Step 3: Export the skybox

Export a PNG equirectangular image for the Panoramic material path, or a six-face cubemap ZIP (paid plans) if your project uses cubemap skyboxes. For HDR lighting workflows, export a .hdr from the HDR pipeline instead.

Step 4: Import and configure in Unity

Drag the PNG into your Assets folder.
In the texture import settings: Texture Shape = 2D, Wrap Mode = Clamp, and disable mip maps.
Create a new Material and set its shader to Skybox/Panoramic.
Assign the texture to the material's Spherical (HDR) slot.
Open Window → Rendering → Lighting → Environment and set the Skybox Material.

Common issues and fixes

Vertical line in the sky → wrap seam not repaired, or Wrap Mode is Repeat: run Fix Seam and set Clamp.
Blurry band at the seam → mip maps enabled: disable mip generation on the skybox texture.
Washed-out sky → texture imported as sRGB twice or exposure mismatch: check color space settings and the material's exposure slider.
Sky doesn't light the scene → PNGs are display-range only: use a .hdr export for real image-based lighting.

Frequently asked questions

What size should a Unity skybox be?

A 4096×2048 equirectangular image looks sharp on desktop; 2048×1024 is enough for mobile or stylized games. The 2:1 aspect ratio must be exact.

Panoramic material or cubemap — which is better in Unity?

Skybox/Panoramic with an equirectangular texture is simpler (one file, one slot) and works for most games. Use a cubemap when your pipeline or a specific material requires six faces.

Can the skybox light my Unity scene?

Yes — use a .hdr HDRI export. Unity imports .hdr natively and uses its real intensities for ambient lighting and reflections.

About Atmos Forge

Atmos Forge is a web-based AI skybox generator for creating seamless 360° equirectangular skyboxes, cubemaps, and HDRI environment maps for game engines and 3D workflows. It combines AI text-to-skybox generation with procedural sky composition tools — seam fixing, suns, moons, planets, star fields, and sprite compositing — and exports game-engine-ready files for Unity, Unreal Engine, Godot, Blender, Three.js, Babylon.js, and WebGL. Atmos Forge is made by Big Monk Games.

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