The complete field guide
A practical guide to every workflow, setting, pass, optimization tool, decal option, and output rule in SPA Material Baker V3.
Complete capability overview
Everything available in SPA Material Baker V3, grouped into one quick reference. Orange cards marked New in this version identify only the latest additions and changed behavior.
New in this versionLatest baker interface
The current interface brings Bake Options, Mesh Settings, Material Settings, Bake Settings, texture passes, Light Data, decal controls, and export naming into one workflow.
Open full-size interface ↗
Select the Static Mesh or Skeletal Mesh actor/component from the Level Editor. The scene target supplies its real transform, component overrides, and data for World Space Correction and Light Data traces.
Updated workflow ↓Leave the panel Material empty to use the selected component's Material Index slot, followed by the mesh asset slot. Select a panel Material when the slot is empty or when an intentional override is needed.
Material rules ↓Choose 0–64 pixels with a default of 3. Values 1–64 apply an exact dilation distance; 0 provides unlimited coverage for regular baked textures.
Pixel Cover guide ↓Bake a grayscale shadow mask from visible Directional, Point, Spot, and Rect lights. Hidden lights and occluders are ignored, while uncovered or unlit texels remain neutral white.
Light Data guide ↓Multiply the Light Data mask into Albedo in linear color space, preserve Albedo alpha, and save one combined Base Color texture without a separate Light Data output.
Combine behavior ↓Bake LOD0 geometry from Static Mesh and Skeletal Mesh components across normal, indexed, batch, UV-channel, generated-material, and GLB workflows. Mesh Optimizer remains Static Mesh-only.
Support details ↓Bake one selected Material Index for focused output, or enable Bake All Index to process every valid mesh material slot into the selected texture passes.
Selection guide ↓Queue multiple scene components, use one shared material or each mesh's assigned materials, and choose a combined atlas or separate Batch Per Mesh texture sets.
Batch modes ↓Create a new one-slot Static Mesh, normalized UV0 atlas, combined texture set, and generated baked material while preserving the original source mesh. Its UV workflow includes Exist UV for an authored channel, Repack UV for existing islands, and Generate UV Atlas for a fresh layout.
Optimizer workflow ↓Choose the LOD0 UV channel used by every baked pass, decal, Light Data texture, and Auto Material sampler. Optional validation checks empty, invalid, and overlapping UV data.
UV channel guide ↓Preserve component transform, bounds, orientation, and primitive data when baking triplanar, PixelNormalWS, object-space, and world-aligned material logic.
Mesh controls ↓Bake Albedo, Normal, Roughness, Metallic, Specular, AO, Light Data, Displacement, Opacity Mask, Emissive, AlphaBlend, and CustomMap with per-pass color-space control.
Output passes ↓Pack Ambient Occlusion into red, Roughness into green, and Metallic into blue for a compact material-data texture with Linear sampling.
Packing reference ↓Bake the real material Opacity Mask as a standalone pass, apply Mask Threshold cleanup when needed, or enable RGBA to place the mask in Albedo/Diffuse alpha while preserving the RGB color result.
RGBA and mask controls ↓Project compatible scene decals and masked mesh overlays into selected outputs with orientation controls, Height Blend, and the reliable Texture Projection workflow.
Detailed Decal guide ↓Create or intelligently update a generated master and material instance from the baked passes, then assign the result to supported mesh components or assets.
Auto Material guide ↓Export selected level mesh actors into one binary glTF file with component materials and textures, with optional JPEG output and adjustable compression.
Export guide ↓Control format, resolution, color space, sharpness, mask threshold, flat or inverted normals, safe /Game output paths, prefixes, UV suffixes, and pass naming.
Quick start · five minutes
Begin with this safe baseline. Add optimization, batching, light data, or decals only after the basic result is correct.
Press Ctrl + F in the Level Editor or use the SPA Materials Baker menu entry. The shortcut focuses the existing window when it is already open.
In this version, always select the Static Mesh or Skeletal Mesh actor/component in the Level Editor viewport, then assign that scene selection in Mesh Settings. Choose the required Material Index for a single-slot bake. The scene component supplies the real transform, component material overrides, and data required by World Space Correction and Light Data.
Leave Material empty to bake the material assigned to the selected scene component's Material Index slot; if there is no component override, the baker checks the mesh asset slot. If that slot is empty, select a material in the baker's Material Settings panel to supply the source. A material chosen in the panel also acts as an intentional override when the slot already contains a material. Enable World Space Correction for triplanar, PixelNormalWS, object-bounds, or world-aligned material logic.
Start at 1K. Enable Dilation UV with 3 Pixel Cover. Select Albedo/Diffuse, Normal, Roughness, and Metallic. Keep masks and numeric data Linear.
Use a valid /Game/… export folder and a short base name. Press Bake, then inspect seams, normal orientation, color space, and asset naming.
Important UV behaviorSPA Material Baker can bake source meshes that use tiled UVs or overlapping UVs; an overlap is not automatically a bake failure. UV Validation is optional because many materials intentionally tile or stack islands. If Validation reports a UV overlap error and the overlap is intentional, turn Validation off and continue. Use a unique, non-overlapping UV channel for Light Data, decal atlases, Mesh Optimizer output, and conventional reusable texture sets, because overlapping surfaces write into the same output texels.
Recommended first testBake one material index at 1024×1024. Raise the resolution only after the result is correct.
Production behavior explained
Complete guidance for scene targets, material resolution, batch baking, Mesh Optimizer, UVs, Pixel Cover, Light Data, Decal Baking, generated materials, and output naming. Orange guides describe new-version behavior.
Source resolution
A mesh is always required. In a normal single-index bake, selecting a material is optional because the baker can read the material from the selected mesh slot.
The baker reads Material Index from the selected scene component first. If no component override exists, it reads that slot from the Static or Skeletal Mesh asset.
The selected material becomes an override. It is baked onto the selected mesh UVs instead of the material currently assigned to that mesh slot.
It is treated as a decal source, not the base mesh material. The baker ignores it as the base and falls back to the selected mesh slot.
Baking stops unless a valid override material is selected. Assign a slot material or choose an override in Material Settings.
The selected material changes what is evaluated; it does not change the target geometry or UVs. The selected mesh always provides the bake surface and selected UV channel.
Multiple scene meshes
Batch Baking accepts level scene components only. Select Static Mesh or Skeletal Mesh actors/components in the viewport and click Add Selected. Content Browser-only entries cannot supply component transforms or correct Light Data shadow tracing.
One material selected in Material Settings
One combined batch/atlas output set
Apply the same material to several meshes
Each component's material slot
One combined atlas using mesh/material pairs
Mixed materials consolidated into shared outputs
Always resolves from each mesh/component slot
A separate named texture set for every mesh
Independent assets and clean per-object delivery
Supported geometry
SPA Material Baker supports Static Meshes and Skeletal Meshes for normal, Bake All Index, batch, Batch Per Mesh, GLB selection, UV-channel selection, Auto Material, and material assignment.
Enabling Mesh Optimizer with a Skeletal Mesh is rejected. Use a normal Skeletal Mesh bake or Batch Per Mesh instead.
One mesh · one material
Mesh Optimizer converts a multi-slot Static Mesh into a new optimized mesh with one material slot, a normalized UV0 layout, a baked texture set, and a generated material.
The mesh must contain at least one material slot and valid LOD0 geometry.
The baker automatically enables Bake All Index, mesh-UV baking, and Auto Material. It disables Batch Baking, Use Meshes Material, Batch Per Mesh, path-relative naming, and direct Assign to Mesh.
The selected strategy determines how every original slot is placed into the new optimized UV0.
All valid material slots are baked into one atlas per selected pass.
The tool creates the optimized Static Mesh, combined textures, master/material instance output, and assigns the generated baked material to the new optimized mesh.
Uses a chosen existing source channel. Best when that channel already has unique, non-overlapping islands suitable for one atlas. When multiple channels exist, the optimizer initially prefers UV1.
Keeps existing island shapes but repacks them into normalized 0–1 space. Use when the topology and seams are good but island placement or scale needs consolidation.
Creates a fresh atlas. Use when existing UVs overlap, tile heavily, waste space, or cannot safely store all material slots in one texture set.
The optimized asset uses one material slot and the new atlas in UV0. The original source mesh and its materials are not replaced.
Texture placement
The UV Channel value selects the LOD0 texture-coordinate channel used to rasterize the bake. The input is automatically clamped to the channels that exist on the selected Static or Skeletal Mesh.
Normal material UVs. Appropriate when islands do not overlap, or when intentional tiled/UDIM behavior is expected by the workflow.
Useful for unique unwraps, lightmap-style layouts, or alternate texture sets. Output names receive _UV1, _UV2, and so on to prevent overwriting UV0 results.
Albedo, masks, normals, ORM, decals, Light Data, and Auto Material texture samplers use the same selected channel.
Enable Validation to check finite/non-empty UV data and overlaps. It is intentionally optional because tiled UVs may overlap by design.
UV edge padding
Dilation UV expands valid edge colors beyond UV islands to reduce seams and filtering artifacts. Pixel Cover controls how far that expansion travels; it does not resize or repack the UV islands themselves.
No edge expansion is performed. Pixel Cover is disabled and has no effect.
Unlimited coverage for regular baked textures: dilation continues until every reachable empty texel is filled. For Light Data, unused texels stay neutral white so shadows do not flood the atlas.
Applies that exact expansion distance in pixels. The default is 3 pixels.
Use enough padding for filtering and mipmaps, but leave room between islands. Larger values can pull colors from neighboring islands and create bleed.
Because Light Data is multiplied with Base Color, its uncovered background must remain white. This prevents empty atlas space from darkening Albedo or spreading black shadow texels beyond real UV coverage.
Scene lighting
Light Data produces a grayscale, texture-space shadow multiplier from scene lights and visibility traces. White is neutral and darker values add shadowing. Direct-light brightness and color are not baked, so the generated material remains Default Lit and Unreal continues to provide the live lighting response.
Saves a _LightData texture so the mask can be adjusted or combined later. Keep this numeric mask Linear.
Automatically enables Base Color and Light Data, multiplies them in linear color space, preserves Albedo alpha, and saves one combined Base Color. The separate Light Data texture is not saved.
0 makes the mask white and removes shadow darkening. 1 preserves the calculated mask; values below 1 lighten shadows and values above 1 deepen them. The setting affects both separate and combined output.
Use a selected level component for correct world transforms, normals, and shadow traces. Batch items must remain linked to their scene components.
Light Data is a reusable shadow/visibility mask, not a replacement for Unreal's lighting. A scene with no relevant visible lights produces neutral white rather than a black texture.
New layered-detail baking
Enable Bake Decals to composite visible scene decals and compatible masked mesh overlays into the texture passes already selected for the base material bake. The target must be a valid scene component so projection and receiver transforms are correct.
Reads compatible decal texture inputs and projects them directly into Albedo, Normal, Roughness, Metallic, AO, ORM, Opacity Mask, and Displacement. It is the fast, stable production path.
Attempts to capture Unreal's rendered decal result for more complex graphs. It is slower, disables projection-orientation controls, and falls back when valid capture data is unavailable.
Decals affect only outputs already selected for the material bake. Missing or incompatible decal inputs are skipped instead of creating unrelated passes.
Use the intended visible decal actors/components around the selected receiver. Scene placement, projection volume, orientation, and receiver geometry determine where the decal is written.
Select the receiver mesh from the Level Editor, enable only the passes the decal should modify, use Texture Projection, then verify orientation before enabling Height Blend or masked overlays.
Generated Unreal material
The baker creates and saves textures only. No master material or material instance is generated.
The baker creates or intelligently rebuilds the generated master and creates a material instance connected to the selected passes, packing choices, and UV channel.
After the generated material is ready, it is assigned to the relevant Static or Skeletal Mesh component/asset material slot.
Auto Material is forced on, but the normal Assign to Mesh control is disabled. The generated material is assigned to the newly created optimized mesh instead.
Safe and predictable output
Export Path
Must be a valid Unreal package path below /Game. Colons, backslashes, double slashes, and external filesystem paths are rejected. Invalid input resets to /Game/BakedTextures and cancels that bake attempt.
Base name
Maximum 30 characters. Use letters, numbers, underscore, and hyphen. Texture output automatically receives the standard T_ prefix when missing.
Material Name
Prefixes the base with the selected override material. When no override is selected in single-index mode, it uses the resolved mesh-slot material name.
Mesh Name
Prefixes the base with the Static or Skeletal Mesh name. It is intentionally not added to combined Batch modes 1 and 2; Batch Per Mesh uses per-mesh naming.
UV suffix
UV0 keeps the normal name. UV1+ adds _UV1, _UV2, etc., preventing different UV-channel bakes from overwriting each other.
Material Index
Non-zero single-index output receives an index suffix where applicable, helping separate slot-specific results.
Pass suffix
Each output adds its pass identity, such as Albedo, Normal, Roughness, LightData, or ORM.
/Game/BakedTextures/T_SM_Chair_Baked_UV1_NormalMesh prefix + base name + selected UV channel + pass name.
Complete control reference
Session mode
Exports all mesh actors currently selected in the Level Editor to one binary glTF file, including component transforms, assigned materials, and textures.
Uses JPEG images for compatible GLB textures to reduce file size. Keep lossless output for normal maps and numeric masks when maximum accuracy matters.
Compression accepts 0–99; higher compression creates smaller, lower-quality JPEGs. Displayed Quality is calculated as 100 − Compression.
Creates a new one-slot Static Mesh, normalizes the final atlas into UV0, bakes every valid material index into combined textures, generates a material, and leaves the original mesh unchanged.
Mesh Optimizer method that uses an authored source UV channel. The final optimized layout is stored in UV0.
Mesh Optimizer method that preserves island shapes while repacking them into normalized 0–1 space.
Mesh Optimizer method that creates a fresh atlas when existing UVs overlap, tile, or are unsuitable for combined output.
Bakes multiple scene mesh actors or components in one run. Select items in the viewport and add them to the Batch Assets List.
Uses every queued mesh's assigned material and slot mapping instead of one manually selected material.
Exports a separate texture set for each queued mesh.
Add Selected queues the current level selection. Remove Selected and Clear manage the list. The list is designed for level scene meshes.
Bake target
Select a Static Mesh or Skeletal Mesh actor/component in the Level Editor viewport and assign that scene selection. The component supplies its real transform, bounds, and material overrides.
Selects one material slot for single-index baking. With the panel Material empty, the baker checks this component slot first and then the mesh asset slot. Disabled by Batch Baking, Bake All Index, and Mesh Optimizer.
Bakes every material slot into the selected outputs. Available for single- and multi-slot meshes.
Selects the mesh UV channel used by the bake. Use a unique, non-overlapping channel for Light Data and atlas-style output.
Preserves component transform, bounds, orientation, and primitive data for world-space, object-space, triplanar, and PixelNormalWS material logic.
Optional UV preflight checking finite and non-empty UV data plus overlap problems. Disabled by default for faster routine baking.
Material source
Optional in a normal single-index bake. Leave it empty to use the selected scene component or mesh asset slot. Choose a /Game material when that slot is empty or to intentionally override an occupied slot.
Enables edge-color expansion around UV islands to reduce seams and filtering artifacts. When disabled, Pixel Cover has no effect.
Sets UV dilation from 0–64 pixels; the default is 3. For regular textures, 0 means unlimited coverage and 1–64 are exact pixel distances. Larger values can bleed into nearby islands. Light Data keeps unused pixels neutral white when set to 0.
Creates a generated Unreal material using the newly baked textures.
Applies the generated material to the selected mesh or component when a compatible target is available.
Texture output
Chooses the output texture format used for the generated assets.
Sets the square bake resolution. Use 1K while testing and increase it for final output.
Writes Ambient Occlusion into red, Roughness into green, and Metallic into blue.
Packs the real material Opacity Mask into Albedo/Diffuse alpha while preserving RGB. It automatically enables Base Color and Opacity Mask and saves one RGBA Albedo texture.
Applies post-bake sharpening. High values can create ringing around hard edges and UV boundaries.
Controls standalone or RGBA-packed Opacity Mask cleanup. Zero preserves the evaluated grayscale mask; higher values create a harder black/white cutoff.
Produces a flat normal map instead of the evaluated material normal.
Flips the normal map green channel for applications using the opposite Y convention.
Each pass has a color-space checkbox: unchecked means Linear, checked means Color/sRGB.
Automatically enables Albedo and Light Data, multiplies the grayscale shadow mask into Albedo in linear color space, preserves alpha, and saves no separate Light Data texture. It does not bake direct-light brightness or color.
Controls shadow darkness from 0–4: 0 removes darkening, 1 preserves the calculated mask, below 1 is lighter, and above 1 is darker. It affects separate and Albedo-combined output.
Texture data map
Select at least one pass. Treat masks and numeric surface data as Linear unless a target pipeline specifically requires otherwise.
Evaluated base color. Can receive baked Light Data and decals.
Evaluated material normal, with optional flat output and Y inversion.
Standalone or green channel in packed ORM.
Standalone or blue channel in packed ORM.
The material's specular response as a separate texture.
Standalone or red channel in packed ORM.
Linear grayscale shadow/visibility multiplier from visible Directional, Point, Spot, and Rect lights. Strength ranges from 0–4, and the mask can be saved separately or multiplied into Albedo.
Reads the real material Displacement path directly.
Reads the real material Opacity Mask input. Save it separately, clean it with Mask Threshold, or enable RGBA to pack it into Albedo alpha.
Captures emissive output with HDR-aware processing.
Custom pass capturing alpha blending through the AO route.
Custom output stored through the AO channel.
Packed data texture
Import and sample the combined map as Linear.
New in this version · Layered surface detail
Bake visible decal actors and compatible masked mesh overlays into passes already selected for the material bake.
Fast and stable. Projects decal texture inputs into Albedo, Normal, Roughness, Metallic, AO, ORM, Opacity Mask, and Displacement.
Attempts to capture Unreal's rendered decal contribution for complex materials. It is slower and may be less predictable.
Uses baked receiver Height/Displacement to reduce decal influence on raised detail.
Texture Projection opens with the tested deferred-decal orientation.
Flattens nearby planar Static Mesh cards into the receiver using their triangles and UV0.
Portable and predictable assets
Export selected scene actors to a portable GLB, or create Unreal texture and material assets below a valid /Game/… path.
Select one or more Static or Skeletal Mesh actors/components in the Level Editor and enable Export GLB. The baker writes one binary glTF file with component transforms, assigned materials, and textures.
/Game/BakedTextures├─ BakedTexture_Albedo
├─ BakedTexture_Normal
└─ BakedTexture_ORM
Maximum 30 characters. Use letters, numbers, underscore, and hyphen.
Saves output relative to the selected mesh or material rather than the entered folder.
Adds the material name to output assets.
Adds mesh and pass names for clear, collision-resistant batch output.
Fast diagnosis
Most incorrect results come from asset location, selection state, UV layout, color space, or an experimental capture path.
Select a Static or Skeletal Mesh component in the Level Editor, choose at least one pass, and enter a valid /Game path. A panel Material is optional when the selected Material Index slot already contains a valid material. In Batch mode, add selected scene meshes to the list.
The mesh target now comes from the Level Editor scene. Select the intended actor/component in the viewport and assign it in Mesh Settings. Panel override materials and created Unreal assets must still be below /Game.
Use a Static Mesh with valid LOD0 geometry and material slots. Choose exactly one optimizer UV method: Exist UV, Repack UV, or Generate UV Atlas. Skeletal Meshes are not supported by Mesh Optimizer.
Choose a non-overlapping UV channel, enable Validation, or use Repack UV / Generate UV Atlas.
Enable World Space Correction and use the intended scene component so transform and bounds are preserved.
Enable Dilation UV and start with the default 3 Pixel Cover. Increase it carefully when islands have enough spacing. Use 0 only when you want unlimited coverage; reduce the value if nearby islands begin to bleed.
Use a unique, non-overlapping UV channel and a selected scene component. Verify that the intended Directional, Point, Spot, or Rect lights and shadow-casting objects are visible in the editor. Hidden lights and occluders are intentionally ignored; areas with no relevant light remain neutral white.
Try 0°, 90°, 180°, or 270°, then adjust Flip U and Flip V. The default is 180° with Flip U enabled.
Switch to Texture Projection. Final Render Capture is experimental and automatically falls back when capture data is invalid.
Use Linear sampling and verify R = AO, G = Roughness, B = Metallic.
Verify that the source material uses the real Opacity Mask input. RGBA automatically enables Albedo and Opacity Mask and stores the mask in Albedo alpha. Set Mask Threshold to 0 to preserve grayscale output, or raise it for a harder cutoff.
Disable Export JPG for lossless texture images, especially normal maps and numeric masks. If JPEG is required, reduce Compression to increase the displayed Quality.
When requesting support
Include Unreal version, mesh and material type, enabled modes, UV channel, passes, and the exact dialog message.