Interpolate/Extrapolate (Horizon)

Use Insight's interpolation/extrapolation operation to fill gaps and holes in horizons.

Regular X/Y, 3D and 2D horizons can be interpolated. To interpolate or extrapolate sparse X/Y horizons, use the regrid operation to convert them to a regular grid.

Note: The Interpolate/Extrapolate button is disabled if the input horizon is waiting for another operation (such as propagation). Insight notifies you to complete the previous operation before continuing.

Where is the Interpolate/Extrapolate operation?

Interpolate/extrapolate is found in the Map View, under the Operations tab (along with other horizon operations).

  1. Open the Map View.
  2. Expand the left panel and open the Operations tab.
  3. At Operation, select Interpolate/Extrapolate.

Tip: Click the Help icon to read more information about this operation.

Configuring Interpolate/Extrapolate

Interpolate/extrapolate a horizon


The default mode (interpolation) fills enclosed regions according to the settings.

  1. In the navigation bar, select the horizon to interpolate.
  2. At Maximum search (m), define the maximum distance.
    • When finding a result at a location, points beyond this distance have no effect.
  3. Interpolation Settings: (see How Interpolation Settings Work)
    • Spreading: natural neighbour weighting
    • Smoothing: inverse-distance weighting
    • Strike/dip: define the influence in the strike direction.
    • Direction (degrees): The azimuth of the strike axis, in degrees (clockwise from North).
  4. At Limit area, select a polygon/probe to constrain the operation.
  5. Enable Faults to prevent the interpolation from crossing fault planes.
    • Insight honours any enabled faults in the Control Panel. Unassigned fault sticks are not used.
  6. Fault Polygon: Fault polygons are excluded from interpolation / extrapolation (if selected)
  7. Click Interpolate to start the operation.


Enable extrapolate to completely fill a specified region according to the settings.

  1. Enable the Extrapolate check box.
    • The maximum search distance has no effect when extrapolating.
  2. Constrain to area field changes to Fill area.
    • (required) Select a polygon/probe to fill
  3. Click Extrapolate to start the operation.

Completing the operation

After running the operation:

  • Click Discard to cancel this calculation and delete the results.
  • Click Replace this horizon to save this horizon containing the extracted values and replace the previous one.
  • Click Save as New Horizon to create a new horizon.

To assist reviewing the results in the 3D and Map Views, interpolated / extrapolated points are displayed in a solid colour. The original values appear semi-transparent. This lasts until the operation is completed.

The following examples show a horizon in the Map View before and after interpolation:

Note: By default, the new horizon will be named: “horizon_name (interp/extrap)”.  For example, the operation above will yield a new horizon called "Sample (interp)". To rename the horizon, see Horizon Details and Configuration.