Variograms: Displaying and Modeling An introduction to displaying and modeling variograms

Introduction

 

This Variogram Display and Modeling functionality, which forms part of the Enhanced Geostatistics (EGS) module, replaces the previous VARFIT command.

 

This Variogram Display and Modeling functionality has the following features:

• Uses the Datamine Charting framework which is shared by the Histograms, Scatter Plots and Stereonet options.

• Report-quality graphics that can be saved as standard image files (.jpeg, .gif, etc) or as plot items in the Plots window.

• Ability to save one or more 'variogram display and modeling scenarios', each as a single case with all its parameters.
  

  A case is set up by creating a new variogram chart sheet, represented by a single tab in the Plots Window.

• The simultaneous opening of multiple cases, together with Histogram, Scatterplot and Stereonet charts.

• Selection of multiple experimental variograms from one or more files created by the variogram calculation process (VGRAM).

• Selection and display of experimental variograms using up to three key fields.

• Interactive model fitting by dragging control points with the mouse or by typing parameters into dialogs.

• Fitting of anisotropic models in a single window, or in three individual windows with full linking of common parameters.

• Choice of model type for up to five structures.

• Detailed formatting options to specify axes, annotation, titles, line styles, colors, etc.

• Display of variogram rotation angles in either the world coordinate system, or relative to a rotated plane.

• Choice of display of variogram, relative variogram, log variogram or covariance. Any of which can be normalized.

• Creation of a wireframe ellipsoid from the variogram model, to aid in visualizing variogram ranges and axis rotation angles.

The Variogram Dialog

The Variogram dialog controls all aspects of histogram display, formatting and modeling. The dialog consists of two functional areas: a preview area on the left and a control area on the right.

The Preview Area

The preview area is used for the following:

• Previewing the current settings for the displayed variogram(s).

• Interactive model fitting.

• Interactive positioning of the following chart components:

• • Chart title box.

  • Variogram model parameters box.

  • Legend box.

The Controls Area

The control area, on the right is, divided into the following tabs:

• Data Selection: load and display experimental variograms from one or more files. More...

• Format: configure the variogram chart's Annotation, Axes, Grid, Comments, Color, Legend and Options parameters. More...

• Charts: control the display of loaded variograms using the folder tree. More...

• Data: view the lag details for the selected variogram. More...

• Model Fitting: fit a model to the current variogram chart. More...

 

 

Creating a New Variogram Chart Sheet

 

Create a new variogram chart sheet, for displaying and optional modelling, using the following steps:

1. In the Plots window, select Insert | Chart | Variogram.

2. As a minimum, in the Data Selection tab, load an experimental variogram file(s), and define the associated parameters. Click Apply.
   

   The above procedure requires the existence of an experimental variogram file. This is typically created using VGRAM( Applications | Statistics | Variograms | Calculate).

3. If a variogram model is to be created, in the Model Fitting tab, specify a model file and define a set of model parameters.

	Related Topics
	Data Selection Format Charts Data Model Fitting