How to Bake Normal Maps: Complete Workflow from High-poly to Low-poly

What is Normal Map Baking?

Normal map baking is the technique of converting surface detail from a high-polygon model into a normal map and applying it to a low-polygon model. This enables game assets to maintain visual detail while dramatically reducing polygon count, improving performance.

Core Concepts:

• High-poly (High-polygon): Millions of polygons, rich detail but unsuitable for real-time rendering
• Low-poly (Low-polygon): Few thousand polygons, game-ready but lacking detail
• Normal map: Texture storing high-poly details, applied to low-poly to simulate detail

Pre-Baking Preparation

1. Prepare High-poly and Low-poly Models

High-poly Recommendations:

Use Subdivision Surface or Multiresolution Modifier to create detail, or import from sculpting software like ZBrush. Ensure the high-poly represents your desired final visual result, with clean geometry and no broken faces.

Low-poly Topology:

Keep polygon count within 5k-15k range, maintain clean quad topology with logical edge flow. Can use manual retopology, Decimate Modifier, or retopology tools. Low-poly silhouette should approximate high-poly, with flat areas kept minimal.

2. UV Unwrapping

UV quality directly impacts baking results. Place seams in inconspicuous areas (bottom, back), avoid stretching or compression, maximize 0-1 UV space, and allocate more area to important regions.

Check Steps:

1. UV Editing workspace - check overlaps (Select → Overlap)
2. Check stretching (Display Stretch)
3. Arrange islands to maximize space utilization

3. Naming Conventions

Character_HighPoly  (High-poly)
Character_LowPoly   (Low-poly)
Character_Normal    (Baked normal map)

Blender Normal Baking Steps

1. Scene Setup

Ensure high-poly and low-poly are at the same location (origins aligned), with models overlapping or very close. Both models’ scales must be Applied (Ctrl + A → Scale). Any model displacement or unapplied transforms will cause baking to fail.

2. Material Node Setup

Low-poly needs a material to receive the baked texture:

1. Select low-poly → Shading workspace
2. Add Image Texture node (Shift + A → Texture → Image Texture)
3. Click New to create new texture
   - Name: Character_Normal
   - Width/Height: 2048x2048 (or 4096)
4. Node doesn't need to connect output, but must be selected (yellow border)

3. Baking Settings and Execution

Selection Order: Select high-poly first (Shift multi-select), then select low-poly last (active object)

Render Properties → Bake Settings:

Bake Type: Normal
✅ Selected to Active

Ray Distance (Light Ray Distance)
- Extrusion: 0.01-0.1
- Max Ray Distance: 0.1-1.0

Output
- Margin: 16px (edge padding to prevent seams)
- ✅ Clear Image

Click Bake to start, wait for progress bar to complete.

4. Save and Apply

Save Normal Map:

UV Editing workspace → Image → Save As → Select PNG format

Test Effect:

1. Set Image Texture node to Non-Color (important!)
2. Connect to Normal Map node
3. Normal Map connects to Principled BSDF Normal
4. Switch to Material Preview to view effect

Common Issues & Troubleshooting

Black or Strange Colors in Results

Cause: High-poly and low-poly too far apart or incorrect Ray Distance settings

Solution: Confirm model alignment, increase Max Ray Distance, adjust Extrusion value

Blurry or Missing Details

Cause: Texture resolution too low or severe UV stretching

Solution: Increase resolution (2048 → 4096), re-unwrap UVs to reduce stretching

Visible Lines at UV Seams

Cause: Margin too small or UV islands too close

Solution: Increase Margin to 16-32px, leave sufficient gaps between UV islands

Advanced Techniques

Cage (Baking Cage)

Duplicate low-poly and slightly enlarge it as a Cage. Enable Cage in Bake settings and select this object to precisely control light ray projection direction and high-poly detail capture range.

Texture Resolution Recommendations

Export to Game Engines

Unity: After importing, set Texture Type to Normal Map in Inspector

Unreal Engine: Set Compression Settings to Normal Map, disable sRGB

Workflow Checklist

Before Baking: High-poly detail complete, low-poly topology reasonable, UVs without overlaps, models aligned with scale Applied

During Baking: Correct selection order (high-poly→low-poly), Image Texture node created and selected, Ray Distance and Margin set appropriately

After Baking: Normal map saved as PNG, effect tested in Blender, exported to game engine and verified

Conclusion

Normal map baking is a core technique in modern game development. Preparation determines 80% of success, UV quality directly affects results, and Ray Distance needs model-specific adjustment. Start with simple models to practice the complete workflow, then progress to complex assets. Record encountered problems and solutions each time, gradually building best practices.

Related Resources:

• Blender Official Baking Documentation

• Blender Normal Map Baking Video Tutorials

• Unity Normal Map Documentation

• Unreal Engine Normal Maps Guide