The Minimum Surfaces are the lowest safety factor surfaces, for a given analysis method, generated at each grid point of a slip center grid.
The Minimum Surfaces option is only applicable when a Grid Search for circular surfaces has been performed, using a slip center grid. It is not applicable for non-circular surfaces.
The display of Minimum Surfaces can be toggled ON or OFF, by selecting the Minimum Surfaces option from the toolbar or the Data menu.
The colours of the Minimum Surfaces correspond to the colours of the safety factor contours in the slip center grid(s), and the Legend. Remember that the safety factor contours in the slip center grid, are obtained by contouring the minimum safety factor values at each grid point. If the contours are customized with the Contour Options dialog, the changes will also affect the Minimum Surfaces.
The Minimum Surfaces correspond to the currently selected Analysis Method (i.e. if you select different analysis methods, you will see different surfaces displayed, since in general, the minimum surfaces and safety factors, calculated at each grid point, may be different for each analysis method)
The Filter Surfaces option can be used to filter the display of Minimum Surfaces (e.g. only surfaces with a safety factor less than some specified value). See the Filter Surfaces topic for details.