Shape Index Map
|meaning||cap||dome||ridge||saddle ridge||saddle||saddle rut||rut||trough||cup|
The shape index is calculated from the principal curvatures of the Hessian, which is very susceptible to noise. Therefore the plugin asks you to specify a radius for Gaussian blurring as a preprocessing step.
With radius 2, this results in the following shape index map (bright spots correspond to caps, dark to cups):