MatCaps¶
Blender comes with some MatCaps included by default. This page gives important context for how they are created and for which users.
Creating MultilayerEXR MatCaps¶
MatCaps can be any standard image file format but it's recommended to use the multilayerEXR format to make use of multiple layers. It's assumed that every .exr MatCap is using the Linear Rec.709 colorspace and includes two layers named: - "diffuse" - "specular"
The diffuse layer will be multiplied onto the objects and the specular layer will be added after.
Rendering MatCaps in Blender¶
Almost all default MatCaps have been rendered from Blender to be able to make adjustments/additions easily in the future.
The files can be found in the blender-asset repository:
blender-assets/working/matcaps/workfiles/. This just requires a perfect sphere and a camera. Most of the MatCaps follow this compositor setup for exporting.
To split the diffuse and specular shading into individual layers we have to enable various render passes and mix them back together manually to get the same result. Since there is no scene to bounce lights we do not need the indirect passes.
The alternative to this is to render separate render layers. This can offer more control for a specific look.
If rendered with Cycles the render also needs to be manually denoised.
Any use of color management such as Filmic and AgX Visual Transforms will not be saved into the .exr file. This is by design, since the .exr format is typically used for further compositing and color management. But since MatCaps are not meant to have further color management settings applied when used in the Blender Workbench shading we have to bake this into the image before exporting it.
To have a look inside that node group, we have to add two nodes: - 'Convert to Display' with the same settings as used in the Color Management render settings. - 'Convert Colorspace' to convert from sRGB to Linear Rec.709
To export the layers correctly into a .exr file we use the 'File Output' node and input the layer results with the names "diffuse" and "specular". For an optimal file size use - Disable 'Save as Render' - 'Float (Half)' color depth - 'DWAA' compression at 50% - Make sure the Color Space is set to 'Linear Re.709
Painting in Krita¶
As an exception the Red Wax MatCap has been painted in Krita, which supports opening and editing multilayerEXR files. This was to achieve a very specific look.
MatCap Purposes¶
The MatCaps are an alternative to the Studio Lights in workbench shading. Both are meant as very easy to use lighting presets.
Studio Lights are limited to 4 physically accurate lights, which change dynamically based on the Roughness and Metallic properties of the material or object. MatCaps on the other hand are a pre-rendered/hand-painted lighting preset which can be much more complex and specific as a result.
Surface Readability¶
MatCaps can give higher surface curvature readability than the alternatives. Even the default "Basic" MatCaps offer a wider gradient than Studio Lights, which is necessary for modeling and sculpting tasks. The "Check" MatCaps provide even stronger or more technical surface readability for working on small surface details and imperfections.
The "Check Reflection" MatCaps also include a small checker pattern which stretches on curvature changes.
Note
For various MatCaps, such as the "Basic" ones, the specular layer strength was kept very subtle to not blow out dark areas. The specular layer is meant to help with readability on dark surfaces without making the material look to shiny or metallic.
Material Preview¶
"Toon" and "Clay" and various "Metal" MatCaps can be a good enough preview of a later rendering style while working on an asset.
Some also come with a colored diffuse layer. The strong difference between the look of MatCaps can help see your model in a context and evaluate the mesh with fresh eyes.