PolySurface Curvature by Jens Kafitz 
 Where to find it:
 Add Procedural Layer / Geometry / Extension Pack /
 NodeGraph / Right Mouse Click / Add Nodes / Geometry / Extension Pack /

From Mari 4.6 onwards this node will no longer be loaded. Use the standard Mari Node 'Curvature' instead 
The Polysurface Curvature Node will detect your models curvature and output a mask
Optionally you can feed in a normal map via the Nodegraph to fine tune the result.

Tesselation Due to MARI & OpenGL limitations Polysurface Curvature does not average the values between individual faces.This can result in tesselated looking masks. It is recommended to flatten the node and apply a Gaussian Blur to filter the mask. 
 Normal Map
Allows you to attach a tangent space normal map that should be used during the calculation.
This can be useful if you have a lowres mesh with baked normal maps from which you want to pick up curvature information
You can use the Mix Normal Map Slider to determine the strength of the Normal Map during the calculation.
 Curvature
Overwrite the Curvature Slider of the Node with a Node Connection
 Min Curvature
Overwrite the Min Curvature Variation Slider of the Node with a Node Connection
 Intensity
Overwrite the Intensity Slider of the Node with a Node Connection
MAIN TAB
 Curvature
Determines the threshold on the curvature. Curvature is evaluated as absolute values meaning there is no difference
between concave and convex curvature being made.
 Min Curvature Variation
Determines the minimum normal difference between two vertex points need to have in order for the curvature to be
calculated
 Intensity
A multiplier on mask.
 Invert
Inverts the result of the mask  black becomes white and white versa.
By utlizing the Nodegraph you can add an additional Normal Map into the calculation of the curvature.
To use this, attached a Normal Map Layer or Channel to the 'Normal Map' Connection in the Nodegraph.
 Mix Normal Map
Determines the interpolation value between the objects normals and your normal map.
 Hard Edged
Hard Edged Mode will clip any greyscale values giving you a 2value mask  pure black & pure white.
 Attenuate by Ambient Occlusion
Attenuate by Ambient Occlusion will multiply your Curvature and Intensity Sliders by Mari's Ambient Occlusion.
You will most likely have to adjust the Intensity to compensate.

Generate Ambient Occlusion 'Attenuate by Ambient Occlusion' relies on Maris pregenerated occlusion to work. Generate Object Occlusion via the OBJECTS Menu first. 