Topography on the 3D head model represents the power distribution of received EEG data.
We calculate the power of each electrode in the 1-40Hz frequency range. Before the final topography plot, we apply a spatial Laplacian filter. This plot is only for visualization and is not stored anywhere. If you want to implement the same plot in your processing tool and are interested in the details of the algorithm, contact us at support@mbraintrain.com