Render Baking¶
Reference
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Cycles shaders and lighting can be baked to image textures. This has a few different purposes, most commonly:
- Baking textures like base color or normal maps for export to game engines.
- Baking ambient occlusion or procedural textures, as a base for texture painting or further edits.
- Creating light maps to provide global illumination or speed up rendering in games.
Setup¶
Baking requires a mesh to have a UV map, and an image texture node with an image to be baked to. The active (last selected) image texture node is used as the baking target.
Use Render Bake in intensive light/shadow solutions, such as AO or soft shadows from area lights. If you bake AO for the main objects, you will not have to enable it for the full render, saving render time.
Cycles uses the render settings (samples, bounces, …) for baking. This way the quality of the baked textures should match the result you get from the rendered scene.
Settings¶
Bake Types¶
- Combined
Bakes all materials, textures, and lighting except specularity.
The passes that contribute to the combined pass can be toggled individually to form the final map.
- Ambient Occlusion
- Bakes ambient occlusion as specified in the World panels. Ignores all lights in the scene.
- Shadow
- Bakes shadows and lighting.
- Normals
Bakes normals to an RGB image.
- Normal Space
Normals can be baked in different spaces:
- Object space
- Normals in object coordinates, independent of object transformation, but dependent on deformation.
- Tangent space
- Normals in tangent space coordinates, independent of object transformation and deformation. This is the default, and the right choice in most cases, since then the normal map can be used for animated objects too.
- Normal Swizzle
- Axis to bake into the red, green and blue channel.
For materials the same spaces can be chosen in the image texture options next to the existing Normal Map setting. For correct results, the setting here should match the setting used for baking.
- UV
- Bakes colors of materials and textures only, without shading.
- Emit
- Bakes Emission, or the Glow color of a material.
- Environment
- Bakes the environment (i.e. the world surface shader defined for the scene) onto the selected object(s) as seen by rays cast from the world origin.
- Diffuse, Glossy, Transmission, Subsurface
Bakes the diffuse, glossiness, transmission of subsurface pass of a material.
- If only color is selected you get the pass color, which is a property of the surface and independent of sampling refinement.
- If color is not selected, you get the direct and/or indirect contributions in gray-scale.
- If color and either direct or indirect are selected, you get the direct and/or indirect contributions colored.
Selected to Active¶
- Select to Active
- Bake shading on the surface of selected objects to the active object. The rays are cast from the low-poly object inwards towards the high-poly object. If the high-poly object is not entirely involved by the low-poly object, you can tweak the rays start point with Ray Distance or Cage Extrusion (depending on whether or not you are using cage). For even more control you can use a Cage Object.
Note
Memory Usage
There is a CPU fixed memory footprint for every object used to bake from. In order to avoid crashes due to lack of memory, the high-poly objects can be joined before the baking process. The render tiles parameter also influence the memory usage, so the bigger the tile the less overhead you have, but the more memory it will take during baking (either in GPU or CPU).
- Cage
- Cast rays to active object from a cage. A cage is a ballooned-out version of the low-poly mesh created either automatically (by adjusting the ray distance) or manually (by specifying an object to use). When not using a cage the rays will conform to the mesh normals. This produces glitches on the edges, but it is a preferable method when baking into planes to avoid the need of adding extra loops around the edges.
- Ray Distance
- Distance to use for the inward ray cast when using selected to active. Ray distance is only available when not using Cage.
- Cage Extrusion
- Distance to use for the inward ray cast when using Selected to Active and Cage. The inward rays are casted from a version of the active object with disabled Edge Split Modifiers. Hard splits (e.g. when the Edge Split Modifier is applied) should be avoided because they will lead to non-smooth normals around the edges.
- Cage
Object to use as cage instead of calculating the cage from the active object with the Cage Extrusion.
Note
When the base mesh extruded does not give good results, you can create a copy of the base mesh and modify it to use as a Cage. Both meshes need to have the same topology (number of faces and face order).
Output¶
- Margin
- Baked result is extended this many pixels beyond the border of each UV “island”, to soften seams in the texture.
- Clear
- If selected, clears the image before baking render.