This week I got a quick tip for you about 'Cavity Maps'. I know that sounds very specific, but it could be very useful for some workflows.
A 'Cavity map' is essentially a more detailed Ambient Occlusion map and is sometimes called 'crevice map'... You might have also heard the term 'Curvature Map. However 'Cavity map' is different than 'Curvature Map... A curvature map actually store the concave and convex edges of a mesh.
ZBrush can produce very useful cavity maps but we can also tweak some settings to produce a 'cavity map' that can be used as curvature:
With default settings and using the Multi Map Exporter plugin (ZPlugin > Multi Map Exporter), these are two maps I generated for the head of this character: Ambient Occlusion on the left and Cavity Map on the right... You'll see the cavity has more contrast and has darker values in the crevices, so it can be used to mask those indentations.
To produce a cavity map that we could use as Curvature, we need more grey-scale values so that we can identify the convex (white), the concave (Black) and the transition between peaks and crevices (grey values) of the model.
Here is a CURVATURE map baked directly in Substance Painter from the High-res mesh (notice how there are a lot more grey values):
'Cavity' as 'Curvature' with ZBrush
The good news, is that we can tweak some settings in ZBrush to produce a Cavity Map that highlights the 'peaks and valleys' of the mesh with more grey values in between... like the Curvature Map in Substance Painter.
So here is the trick... ZBrush creates the 'Cavity Map' using the settings from the 'Mask by Cavity' section of the Masking Palette. Below is an image of the Cavity Made using the default intensity and profile curve...
But with a little tweaking of the curve and reducing the intensity value you can produce a map that works quite well as a curvature map and can drive 'edge damage' effects and all the good stuff from substance painter.
For this model, a value of 5 in the intensity and a 'smoother' profile curve worked great:
Multiple subtools
Although with this technique you might have to tweak the intensity and profile curve individually for each mesh, if you use the Multi Map exporter, you can enable the 'Use Curve All subTools' switch under the 'Cavity Map' settings and ZBrush will apply the settings of the 'Mask by Cavity' section to produce the maps for all your subtools :
Here is a side-by-side screenshot using the 'Curvature Map baked in Susbtance Painter' (left) and the imported 'Cavity Map' from ZBrush (right) to drive the same effect. So, for practical purposes, you can achieve the same thing and even use the cavity from ZBrush, as 'input' in the Mesh Maps of Substance Painter to drive things like the generators:
Alright, that's it for today! I hope find this info useful and I'll see you next week!