General Module Function
The Fence Geology module uses data in specially formatted .geo files to model the surfaces of geologic layers in vertical planes, or cross sections. Fence Geology essentially creates layers of quadrilateral (4 node) elements (in a vertical plane) in which each node (and element) is assigned to an individual geologic layer. The output of Fence_Geology is a data field, consisting of a 2D line with each layers elevation as nodal data elements, that can be sent to the Krig Fence and 3D Geology Map modules where the quadrilateral elements are connected to the element nodes in adjacent geologic surfaces to create layers along the fence.
Module Input Ports
The Fence Geology module (shown above) has two input ports:
The first input port (leftmost) is the input .geo file.
The second input port (Available only in EVS-Pro) is for a data field consisting of line data. For example the output of Click Sketch or Read_Lines. This allows the user to define a Fence that is not drawn from boring to boring.
Module Output Ports
Fence Geology has three output ports.
The left port is the filename.
(brown-grey-green/brown-yellow/brown) : Provides geologic material information for the Legend module.
The right port is a data field consisting of a 2D line with layer elevation at each node.
Module Status: Interruptible
This module's computational processes can be terminated (interrupted) using the "C Tech" icon in the Windows Notification Area (aka System Tray) in the lower right corner of your desktop. If you hover over the icon, it will tell you the status of the module and expected completion time. Double-Right-Clicking will terminate the process. Note that if you do stop any process, the output of the module is corrupted and any downstream module's results are not usable. You will need to re-run the module.
Module Control Panel
The control panel for Fence_Geology is shown above. Input files are read into the module using the Fence .GEO File button, which presents a standard windows style file browser. The general format of .geo files is discussed in detail in the geo file format section of the help system. Fence Geology input files contain only those borings that the user wishes to include for an individual cross section of the fence, in the order that they will be connected along the section. Each instance of Fence Geology produces one cross section, so that building a fence diagram requires instancing as many Fence Geology (and Krig Fence) modules as there are individual sections in the diagram. The order of the boring listings determines the connectivity of the fence diagram, and must match the order of the borings in the associated analyte (e.g. chemistry) file used in Krig Fence. The data for the boring(s) at which individual sections will be joined to produce the fence diagram are included in each of the .geo files that will intersect. The Fence Geology module begins running when the user clicks on the Accept All Current Values button.
Module Parameter Subpanels
Fence Geology has two subpanels, which allow the user to set the parameters used for the semivariogram production and execution of kriging. Clicking on either the check boxes next to the subpanel names or on the names themselves will bring up the subpanel data entry screens. Note that the subpanels can only be closed by clicking on the box in the Module Control Panel, (they cannot be closed by clicking on the subpanel’s window control icon).
The Semivariogram Parameters subpanel is shown in the above figure. . The pair search range specifies the radial distance from any input data point that will be searched to assemble the data pairs that are used in the variance analysis. The values in the data windows are changed by clicking in the window and using standard windows style editing procedures. The default value for the pair search range is set to 0, which if left alone, results in the value being set to approximately 2/3 of the largest distance between data points in the data set. The user must consider the spatial characteristics of the data set when setting or revising the default calculated Pair Search Range. If large areas exist in the data domain that do not have data points within them, the user must set the Pair Search Range to a value that will allow a pair of data points to be identified, if these outlying data are going to affect the characteristics of the semivariogram. Data sets with large variations over short distances can be modeled most accurately using smaller pair search ranges, as this effectively limits the distance over which the semivariogram will search for and include data points.
The Kriging Parameters subpanel is shown in the above figure. The Reach input field defines the radial distance in the plane defined by the cross section (in user units) from any given model node that the kriging module will look for data points to be included in the estimation of the model parameter at that node. The default value of reach is 0, which results in the module calculating a reach value which is approximately two-thirds of the longest distance between any two data points in the data set. Note that the reach must be set to a value which allows the kriging algorithm to find at least one point, or else kriging of the property value cannot be completed at that model node.
The Points parameter defines the maximum number of data points (within the specified reach) that will be considered for the parameter estimation at a model node. The default value for points is 20, which generally provides reasonably smooth modeled parameter distributions. The effects of decreasing and increasing the values for reach and points on the model output are somewhat similar, but for different reasons. If the data have a fairly even spatial distribution throughout the domain, then increasing these values will generally include more of the input data points that will be used to krige the value for a given model node, and thus will result in smoother modeled data distributions. Decreasing the values of reach and points (in an evenly distributed data set) results in fewer input data points being used to calculate the parameter estimates at a given model node, and result in modeled distributions with greater variations across smaller areas.
The user should consider both the spatial distribution and the range of values in the input data set when deciding upon values for the reach and points parameters. If the specified kriging reach is too small to allow the kriging module to locate at least one point within the search area, then kriging will not be completed for that node, the property value will be set to 0, and the confidence value will be set to 0.1%. Note that this predicted property value could represent an inappropriate value. Therefore, the user should always examine the kriging confidence distribution to evaluate whether the kriging is producing reliable estimates in all areas of the model domain.
If the user specifies a large number of points (that are within the specified reach), then the output will be smoother, but the execution time for the kriging can increase significantly. By posting the input data using the Map Spheres module, and looking at the characteristics of the resulting kriged data using the plume_shell and Statistics modules, the user can quickly analyze the characteristics and distribution of the kriging output for a given set of parameters, and test the effects of changing the kriging parameter values.
The X_Y Plane Res parameters specify the number of grid nodes that will be included along the arc length of the cross section (or fence). The number of grid elements along the arc length of the model is simply the X _Y Plane Res value minus one, as every element has two bounding nodes. The default value for this parameter is 51, but the user can specify any number desired, up to the limit of available memory resources in the computer and run time limitations imposed by the patience of the user. The robust kriging algorithms in EVS generally produce reasonable modeled distributions with a fewer number of grid nodes than the user may be used to, so the recommended procedure for setting the X_Y Plane Res parameter is to start with less, and then increase the value until an acceptable model is obtained.
The Quadrant Search toggle changes the method by which data sample points are selected for inclusion in the kriging matrix. If this is on, the "Points" parameter switches to "Max Points in Quadrant". Searching is performed for each of the four quadrants surrounding the point to be kriged. Within each quadrant a maximum number of points (up to one-half of the total points) are selected. Then, points are taken sequentially from each quadrant up to the maximum number of total points or until all quadrant’s points have been used. The panel display changes when this option is selected as shown above.
The Krig .GEO files in thickness space toggle off causes GEO files to be kriged like GMF files. Each surface get kriged independently of the other surface instead of being kriged in thickness space. This only applies to GEO files without the $W/$G flags.
The Pinch Factor parameter provides the ability to control where pinching occurs between positive thicknesses and borings having the pinch flag. It defaults to 1.0 which causes pinching to occur approximately half-way between positive thicknesses and borings having the pinch flag. When older applications created before version 9.5 are loaded they will have a value of 0.0 for backwards compatibility.
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