The feature surface element is used to define a complex surface specified by outlines, contours, break-lines and points.  This element
      is most commonly used for take-offs such as those needed by contractors for bidding purposes.
    
    
      The properties that are exposed for this element are summarised below.
    
    
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              Define
              
                This is the way that the surface levels should be defined.  Options are 'levels' which uses the levels specified without 
                modification, 'levels & offset' which applies an offset
                to the levels specified.  The offset option is mostly used to add construction thicknesses by specifying a negative 
                offset.  Lastly a 'levels & 3d offset' option allows the
                surface to be adjusted in X and Y as well as in Z.
              
              Offset
              
                This option is only visible if offset options are selected in the 'Define' menu.  It allows you to offset the entire
                surface in X,Y and Z.  This is useful for accommodating for a construction thickness of finding a balance.
              
              Features
              
                The edit button will open the take-off window so that you can defined the outlines, contours, break-lines and points which define 
                this surface.  For more information on the options available in the take-off window see 
                
                  Feature Surface
                
              
              Mode
              
                This is used to specify if the surface should have cut, fill or both.  Most commonly cut and fill will be specified.
              
              Side Batter
              
                The feature surface boundary is joined to the ground by side slopes.  The side batter (set as a ratio of vertical to horizontal) 
                dictates the angle of these slopes.  You can set differet side batter angles for side slopes that cut into
                the ground and for those that fill into it.  Turning side batter off will result in the feature surface being joined to the 
                ground with vertical sides.
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            The following video tutorials relate to this topic :
           
            [1] Proposed Earthworks : The Surface Element : A 
            video which demonstrates how to easily produce estimates for any proposed earthworks defined by survey points, contour lines and break lines.
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