The interpolation dialog sets up a new point data Interpolation. After the interpolation has finished a dataset and a 3D object is automatically created and added to the project. From XYZ point data a new surface is created using 2D interpolation. From XYZVal point data a new 3D Grid is created using 3D interpolation.
In the Algorithm tab the type of interpolation is selected and configured. 2D interpolation algorithms produce surfaces. 3D interpolation algorithms produce 3D Grids. See description of Inverse Distance Weighted, Nearest Neighbor and Kriging.
First step is to select the point data that should be interpolated. The source object is already selected when the dialog is shown. When the Get Data button is pressed the interpolation dialog is asking the source object for point data. The result of pressing the Get Data button depends on the type of source object. For XYZ Points and Chem5 Water Chemistry the Select XYZ Point Data dialog is shown, whereas the Select Resistivity XYZ Data dialog is shown for ODV Models. When data has been retrieved from the source object summary information is shown for the data.
Get Data…: Opens the select XYZ Point data dialog
Statistics…: Shows XYZ Statistics Dialog for selected XYZ point data
Export…: Exports XYZ Points to a *.csv file.
When Inverse Distance Weighting is selected as the interpolation algorithm the Region Tab is visible.
When Kriging is selected as the interpolation algorithm the Variogram Tab is visible. Press the “Edit” button to open the Variogram Editor. Note: The variogram is a fundamental part of Kriging and a careful variogram analysis is necessary for successful Kriging.
See Kriging.
Exponent: Distance weighting exponent. A low exponent produces rounded spikes, whereas higher exponents produce steep spikes
See Inverse Distance Weighted
Smooth Factor: If smooth factor is larger than zero each data point weight is reduced and the interpolation will produce a smoother grid. Beware that smoothin will result in a grid surface that is not exact, meaning that grid node values might be larger or smaller than the input data point values. If smooth factor is zero the resulting grid will be exact. Grids may also be smoothed in the GeoScene3D Toolbox
Max Count:
Kriging Type: Kriging type may be Simple or Ordinary. For most purposes ordinary Kriging is the best choice.
Variance Grid File: Produces an extra grid file containing the variance. The grid file name is identical to the interpolated grid file name with the addition of a _ckgedit_QUOTVariance“ prefix.
Data Count Per Search: Minimum and maximum allowed number of data points per estimate. If the maximum number of points within the search ellipsis is exceeded the closest points are used.
Block Discretization: For values higher than 1 block kriging is performed.
Value Trimming Limits: Data values below the Lower and above the Upper limit are not included in the Kriging.
Octant Search: Maximum number of data per search ellipsoid octant in 3D (quadrant for ellipsis in 2D).
See Kriging.
When the grid is interpolated (2D and 3D) the grid nodes are interpolated one by one. In the search tab it is specified how far away from the interpolated grid point the algorithm should look for data points. If no data points are within search radius the grid node will be blank in the resulting grid.
Search Ellipsis/Ellipsoid: In 2D interpolation X and Y describes the major and minor radius in the search ellipsis. For 3D interpolation X, Y and Z describes the major, minor, and vertical radius in the search ellipsoid.
Search Ellipsis/Ellipsoid Angle: Rotation angle of the search ellipsis/ellipsoid. In 2D Angle 1 rotates the search ellipsis clockwise around the vertical Z axis. In 3D Angle 2 rotates the ellipsis around the rotated Y axis (“dip”). In 3D angle 3 rotates the ellipsis around the rotated X axis (“plunge”).
See Kriging.
In the geometry grid tab the size and geometry of the resulting grid is defined.
Grid Extent (corner node coordinates)
Enter the min and max X, Y, and Z coordinates of the resulting grid. For 2D Grids min and max X and Y coordinates must be specified. For 3D grids min and max Z coordinates must also be specified.
Adjust: Adjusts (rounds) grid extent to the selected node spacing and node count. Max = min + (node spacing * node count).
Data Extent: Sets grid extent to min and max coordinates of the source data points that is about to be interpolated. In other words the smallest grid extent that will cover all data points.
Scene Extent: Sets grid extent to the current scene extent.
Node Spacing
Distance between grid nodes in X, Y, and Z directions. Node spacing is a function of the side length of the grid and the number of nodes. Example: X node spacing = X side length / (X node count - 1). Note: 2D grids must have equal node spacing in X and Y.
Node Count
Number of grid nodes in X, Y, and Z directions.
Grid Info
Information about width, height, depth, and number of nodes in the resulting grid.
In the destination tab the interpolated grid file destination is specified.
New Surface Object:
A new surface or 3D grid object and dataset and source will be created. The new surface of 3D grid will be added to the project.
Grid Filename(*.grd): Specify the file name including path for the resulting grid file.
Surface Object Name: Name of the 3D object (surface or 3D grid) that will be created.
Grid Dataset Name: Specify a name for the dataset that will be created for the grid.
Object Group Node (optional):Select which group node the new object belongs.
Replace Existing Surface/3D Grid
The output from the interpolation replaces an existing surface or 3D Grid and overwrites the existing source file. The existing surface or 3D Grid will be updated with the new data from the interpolation.
When this tab is visible partial interpolation is possible. Partial interpolation means that even when working in a local scene extent with only a fraction of both source data points and destination grid visible, the entire grid is updated seamlessly.
Partial Interpolation: Only the portion of the grid that will be modified by the interpolation is updated. Recommended if the grid file is up to data. Data along the current source data extent may be included in the interpolation.
Full Interpolation: The entire destination grid will be interpolated and updated. All source data required to interpolated the entire grid is extracted from source. This may be time consuming in case of large amounts of data, but may be necessary if the destination grid is not up to data, i.e., if you know that data outside the current source data extent has changed.
See also:
Introduction to Interpolation
2D Interpolation Tutorial
3D Interpolation Tutorial