Surfaces Gridding Properties

Surfer can automatically Create Surface for each contact you have defined from your drillhole data. These surfaces, which are visible in the 3D view, are defined by the contact points and can be further customized. Before creating surfaces, you must first create contacts for your drillholes using Create Contact.

When you select the Surfaces group in the Contents window, the Properties window will display General and Gridding tabs for the contact surfaces.

The Gridding tab contains the options to control the gridding parameters for all the surfaces. All the surfaces uses the same gridding parameters.

 

  • Gridding method: Select a Gridding Method for gridding the data. The default is Radial Basis Function and provides a very good fit for most contacts.

  • Assign NoData outside of: You can set this to None, Convex Hull or an Alpha Shape, if you would like finer control over the extents of the surfaces. In this case, select Convex hull. =

  • Set Inflate convex hull: The 2D convex hull of a data set is the smallest convex polygon containing all the data. The 2D convex hull can be thought of as a rubber band that encompasses all data points. The rubber band only touches the outside points. Set the Inflate convex hull value to expand or contract the 2D convex hull. When set to zero, the boundary connects the outside data points exactly. When set to a positive value, the surface area drawn is moved outside the 2D convex hull boundary by the number of map units specified. When set to a negative value, the surface area drawn is moved inside the 2D convex hull boundary by the number of map units specified. Values are in horizontal (X) map units.

To control the resolution of the surfaces, you can set either the # of Nodes (how many grid nodes there are in either direction) or you can set the Spacing (the spacing between nodes). These two parameters are dependent on each other, so when you change the # of Nodes, the Spacing will automatically update, and vice versa. You can leave these set to the default values.

  • # of Nodes

    • # of X nodes: The # of Nodes in the X Direction is the number of grid columns making up the surface.

    • # of Y nodes: The # of Nodes in the Y Direction is the number of grid rows making up the surface.

  • Spacing

    • X spacing:The X spacing is in the X Direction is the distance in data units between adjacent columns making up the surface.

    • Y spacing:The Y spacing is in the X Direction is the distance in data units between adjacent columns making up the surface.

Golden Nugget : If you want to use a different gridding method or advanced options, export the contact points and grid the contact points using Grid Data and then add that grid back as a layer to the map.

Gridding Notes

  • If for any reason the gridding can’t be completed, a warning or error will be issued.

  • Note that for deviated holes, the Hole Deviation source/TVD method is inherited from the drillhole layer itself in the 2D view.