Cokriging

To run this function: Choose Block model > Estimation > GSLIB > Cokriging, or...

In the Function Chooser, type BM GSLIB COKB3D, and press ENTER.

Fields on the GSLIB interface: Cokriging (cokb3d) form

Files tab

Field	Description
Location	The location of the string file that contains the sample data.
ID Number	The ID range of the string file that contains the sample data.
String range	The range to use for estimation.
D-fields	The description fields that contain the data to use for estimation.
Minimum	All samples less than this value are not used in estimation.
Maximum	All samples greater than this value are not used for estimation.
Estimate	The attribute that stores the estimated grade of each block. If a block is not estimated this attribute is given a background value of -999.
Estimation variance	The attribute that stores the kriging variance for each block.
Constrain interpolation	Selected: The block model is constrained before estimation. Cleared: The block model is not constrained.
Debug file	The name of the GSLIB debug file created.
Debug level	The level of detail included in the debug output file. The higher the debugging level, the more output. The none and low levels summarise the results. Medium and high levels provide all the kriging matrices and data used for the estimation of every point/block. It is recommended that you do not use a high debugging level with a large block model.
Clean up	Selected: The temporary files created, for input to or output from GSLIB, are deleted after estimation is completed. Cleared: The temporary files created, for input to or output from GSLIB, are not deleted after estimation is completed.

Kriging Options tab

Field	Description
Kriging type	The type of kriging to use. The options are: Simple co-kriging Standardised ordinary co-kriging (with re-centered variables and a single unbiasedness constraint) Traditional ordinary co-kriging Note: For Simple co-kriging and Standardized ordinary co-kriging, a mean column is displayed on the Files tab so that you can specify a mean for each variable. GSLIB calculates the data residuals from these means.
Minimum primary samples to krige a block	The minimum number of data points for the primary variable to use for kriging a block. If fewer than this number of samples are found, the block is not estimated.
Maximum primary samples to krige a block	The maximum number of data points for the primary variable to use for kriging a block. For example, specifying 8 uses the closest eight sample points to the centroid of the block being sampled.
Maximum secondary samples to krige a block	The maximum number of data points for the secondary and subsequent variables to use for kriging a block.
Block descretization	The number of descretisation points in X, Y, and Z. These points are evenly distributed on an X x Y x Z grid inside each block being estimated. If you set the number of descretisation points to 1 for X, Y, and Z, point kriging is performed at the block centroid.
Primary Search radius	The search radius for the primary variable in the maximum horizontal direction (hMax), the minimum horizontal direction (hMin), and the vertical direction (Vert). See Ellipsoid Definition for more detail on specifying these radii.
Secondary search radius	The search radius for the secondary variables in the maximum horizontal direction (hMax), the minimum horizontal direction (hMin), and the vertical direction (Vert). See Ellipsoid Definition for more detail on specifying these radii.
Search angles	The angle parameters that describe the orientation of the search ellipsoid. See Ellipsoid Definition for more detail on specifying these angles.

Variograms tab

Field	Description
Nugget	The nugget constant for the variogram.
Type	The type of structure represented by the structure. The structure types supported by GSLIB are: Spherical Exponential Gaussian Hole effect
Cc	The sill for this structure.
hMax	The maximum horizontal range. See Ellipsoid Definition for more detail on specifying these values.
hMin	The minimum horizontal range. See Ellipsoid Definition for more detail on specifying these values.
Vert	The vertical range. See Ellipsoid Definition for more detail on specifying these values.
Angle1	The first angle defining the geometric anisotropy. See Ellipsoid Definition for more detail on specifying these angles.
Angle2	The second angle defining the geometric anisotropy. See Ellipsoid Definition for more detail on specifying these angles.
Angle3	The third angle defining the geometric anisotropy. See Ellipsoid Definition for more detail on specifying these angles.

Result

After you click Apply the information you have selected is sent to GSLIB.

The flow of data is described in the following diagram:

Messages

Message	Description
`Error loading file filename0.str`	There was an error loading the specified string file.
`You must select a model first.`	You must load a block model before you can use this function.
`File c:\Program Files\Gslib90\cokb3d.exe not found`	cokb3d.exe could not be found in the specified directory. Make sure the gslib90 user option is pointing to the directory containing kt3d.exe.
`You have terminated "c:\Program Files\Gslib90\cokb3d.exe" sample.par. Results were not loaded.`	You chose to abort the kriging process. This terminated the executable before the results were loaded.
`"c:\Program Files\Gslib90\cokb3d.exe" sample.par terminated prematurely. Results were not loaded.`	cokb3d crashed or otherwise ended prematurely (for example, it was terminated outside of Surpac by using Task Manager) before the results were loaded.
`Error writing file "sample.dat".` `Error writing file "sample.par".`	An error occurred while writing the specified file. Check that there is enough disk space available to write the file.
`Error opening file sample.dat` `Error opening file sample.par`	An error occurred while trying to open the specified file for writing. Check that the file is not read-only or in use by another process.
`Error opening file sample.out`	An error occurred while trying to open the specified file for reading. Check that kt3d.exe did not end prematurely and that the file is not in use by another process.
`You have terminated the loading of results.` `Results were only partially loaded.`	You chose to abort the block model loading process.