Why does my baked lightmap show banding on a curved surface?

Two causes: low texel density across the curve (each lightmap pixel covers too much area), or 8-bit quantization where smooth gradients step. Bump per-object Lightmap Resolution and switch lightmap encoding to HDR.

How does Lightmap Resolution per object work?

On the MeshRenderer, override Scale In Lightmap. 1 = scene default. Higher values give the object more lightmap space, finer texel density. Curved hero geometry often needs 2-4x; flat walls 0.5x.

Should I use Progressive GPU or CPU?

GPU is much faster on a capable GPU. Quality is identical. Use GPU unless you hit memory limits or need a feature only CPU supports (rare). Settings → Lightmapping Settings → Lightmapper.

Fix: Unity Baked Lightmap Banding on Curved Surfaces

Quick answer: Lighting Settings → Lightmap Encoding = High Quality (HDR). Per-object Scale In Lightmap = 2–4 on curved hero meshes. Direct Samples 32, Indirect 256, Filter on. Re-bake.

Cylinder column under a soft area light shows visible posterized rings instead of smooth gradient. Lightmap is undersampling and 8-bit-quantizing.

The Symptom

Smooth curved surfaces show stepped lighting in baked output. Real-time view (preview) is smooth; only the bake quantizes.

The Fix

Step 1: HDR lightmaps. Lighting Settings → Lightmap Encoding → High Quality (or Normal Quality if memory-constrained). Default Low Quality is 8-bit RGB and bands easily.

Step 2: Per-object Scale In Lightmap.

MeshRenderer Inspector → Lightmapping:
  Scale In Lightmap:    3.0     // 3x default for curved hero
  Stitch Seams:         true

Hero curved geometry now occupies a larger lightmap region; each texel covers less surface area; the gradient resolves.

Step 3: Sample counts.

Lighting Settings:
  Direct Samples:      32
  Indirect Samples:    256
  Environment Samples: 256
  Filtering:           Auto (Gaussian)

Bake takes longer; quality smooths.

Verifying

Bake. Sample the output texture in the Lighting window. Smooth gradient on the curve, no rings. If still banded, raise Scale In Lightmap further or check that Lightmap Encoding wasn’t reverted to Low.

“HDR encoding. Higher per-object scale on heroes. More samples. Bake smooths.”

Related Issues

For light probe seams, see light probe seams. For lightmap UV overlap, see UV overlap.

HDR. Density. Samples. Smooth gradients.