Kriging from a Control File

Use the Grid and Image > Gridding > From Control File > Kriging Control File menu option (KGCON GX) to create a minimum curvature grid using a KRIGRID control file. The GX enables you to create and/or edit a KRIGRID control file, which provides access to all gridding parameters.

Kriging Control File dialog options

Channel	Select the channel to grid from the drop-down list, which is populated based on the currently selected database. Script Parameter: KGCON.CHAN
Output grid	Specify the name of the output grid file. Script Parameter: KGCON.GRID
Control file	Select the KRIGRID control file. Script Parameter: KGCON.CONTROL
Optional error grid	If specified, the standard deviation of error will be placed in this grid. Script Parameter: KGCON.GRID_ERROR
Optional input variogram	If specified, this file will be used as the variogram model rather than the variogram calculated from the data. Script Parameter: KGCON.VAR_IN
Output variogram	Specify the name of the output file that will contain the calculated variogram. Script Parameter: KGCON.VAR_OUT
[Grid]	Create a grid using Kriging.
[Variogram]	Create an output variogram only (no grid).
[Edit Controls]	This button enables you to edit the specified control file, using your default text editor. If the control file does not exist, pressing the Edit Controls button will create a blank control file using krigrid.con from the ...\Geosoft\Desktop Applications \etc directory.

Application Notes

Simple Kriging

The simplest way to use KRIGRID is by entering nothing in the control file and then gridding your data. The cell size will default to one quarter the average data interval. This is based upon dividing the grid area by the number of data points. The power model with a power of 1 (linear) will be used. You may want to adjust the cell size to suit your needs. The coefficient of the power term in the power model (i.e. slope, for a linear model) is calculated by fitting a straight line to the observed variogram. The nugget will be 0, and the variogram data is inversely weighted as a function of h.

Using this procedure, the power model will best fit the start of the variogram. Using the default method, the interpolation will not be very good at distances beyond where the observed variogram deviates from the line defined by the model. Furthermore, the error estimates will also be incorrect in these areas. The Variogram describes the use of the variogram and how to choose an appropriate model in more detail.