Image-based lighting (IBL) is how most PBR lookdev should start. The environment, usually an HDRI, lights the scene and appears in reflections. Your maps then have something physically plausible to respond to. Without IBL, roughness and metalness are guesses against a gray void. This article is the material-side companion to HDRI and PBR: perfect lighting setup.

What IBL actually computes

A typical IBL split is a low-frequency irradiance (or SH) term for diffuse, and a prefiltered specular cubemap sampled with roughness as the mip level. That is why a roughness of 0 shows a sharp environment and a roughness of 0.8 shows a blurry wash. The split assumes energy conservation: as roughness rises, the highlight widens and the peak intensity drops. If your shader skips that, IBL will look like a bright sticker on rough surfaces.

PBR map roles stay the same. Albedo tints diffuse for dielectrics and tints specular for metals. Read the complete PBR texture guide if those slots are still fuzzy.

Pick an HDRI that can judge materials

Use a high dynamic range file, not a JPEG panorama. You need sun or window values well above 1.0 so metals can clip in a filmic view transform the way real chrome does. For lookdev, keep two HDRIs: a neutral studio and an overcast exterior. If a wood floor only looks correct in one of them, the albedo or roughness is compensating for light.

  • Rotate the HDRI to place the brightest source where a key light would sit.
  • Match intensity to your exposure. Do not crank albedo to fix a dim world.
  • Avoid HDRIs with baked colored gels unless the shot needs that mood. They hide map errors.

How to read roughness and metalness under IBL

Place a chrome sphere (metalness 1, roughness 0, albedo mid-gray to white) and a 50% gray dielectric sphere (metalness 0, roughness 0.4) next to the asset. If the chrome does not show the HDRI, IBL is not reaching the shader. If the gray ball is black, exposure or GI is wrong, not the texture.

Then swap in library maps. Brushed metal should streak the environment, not disappear. Satin wood should show a wide, dim highlight, not a mirror. Download free CC0 sets from the Locker3d library and test them on those two spheres before you dress a full scene.

IBL plus local lights

IBL is a fill and a reflection source. Add a local key when you need a readable silhouette or a product highlight that the panorama does not provide. Keep local lights in the same exposure range. A 1000-lux HDRI plus a 10-million-strength area light means the textures were authored against the HDRI and will look blown on the key side.

In Blender, use an Environment Texture on World and filmic or AgX. In Unreal, a sky cubemap or HDRI Backdrop. In Unity HDRP, an HDRI Sky plus ambient mode that actually samples it. Resolution of the specular cubemap should be high enough for hero metals; 256² is often too soft for close-up chrome. Texture resolution on the asset is a separate budget; see the 1K–8K guide.

Common IBL mistakes with PBR maps

  • Albedo with baked contact shadows. IBL adds its own occlusion; the surface goes dirty twice.
  • Metalness of 0.5 on “dirty metal.” Use 1.0 metal and a dirt layer in albedo/roughness, or a dielectric dust coat. Mid metalness looks like oily plastic under IBL.
  • Using an LDR sky and then raising roughness to hide the missing highlight.

Locker3d maps are free CC0, so you can strip baked lighting from a copy if a pack is not clean. License notes: CC0 what you can and cannot do. More lighting articles sit on the blog.

Frequently asked questions

Is IBL the same as using an HDRI?

An HDRI is the usual source for IBL. IBL is the technique: the environment lights the scene and provides reflections. You can also use cubemaps or engine sky systems that were generated from an HDRI.

Why do my PBR metals look gray under IBL?

Metalness uses albedo as the reflection tint. If albedo is too dark, the metal has nothing to reflect. Also check that the HDRI has real highlights; a clipped LDR panorama cannot light a chrome sphere.

Should I add extra lights on top of IBL?

Yes, for shape and product control. Keep IBL as the fill and reflection source, then add a key or rim. If you drown the HDRI with ten spots, you lose the point of image-based lighting.