Variography

Overview

Use the Variograms tools to:

• Create experimental variograms
• Create one or more directions per variogram
• Generate sample pairs
• Display and compare experimental curves
• Build and calibrate variogram models for later kriging workflows

You can open the variogram workspace with shortcut V or from the Variograms button in the ribbon.

Recommended Workflow

1. Create a new experimental variogram.
2. Create directions for that variogram.
3. Generate pairs for the selected directions.
4. Open the chart to review experimental curves.
5. Build and adjust model components.

Create an Experimental Variogram

Create a new item from Create > New Experimental Variogram.

An experimental variogram can contain:

• Multiple directions
• One model per variable

You can create as many experimental variograms as needed.

Direction Creation Options

After creating an experimental variogram, choose one of the following direction methods.

New Direction

Creates one custom direction where you define orientation and pair-calculation parameters manually.

13 Magnificent Directions

Creates 13 predefined directions intended to provide broad 3D directional coverage.

All Directions in a Plane

Creates multiple directions inside a selected section (plane), based on the tolerance you define.

Orthogonal Directions

Starting from a selected main direction, creates two additional perpendicular directions.

You are prompted to select a section because the section orientation is used to build the orthogonal set.

Direction Along Hole

Creates a direction preset for along-hole analysis.

Default preset behavior:

• Tolerance: 180°
• Max distance: 25
• Lag: 1

By Ellipsoid Axis

Creates directions from selected ellipsoid axes (major, medium, and minor orientation workflow).

Generate Pairs

Use Generate > Generate Pairs after selecting one or more directions or variograms.

Important behavior:

• If you select a variogram, pair generation runs for its directions.
• If some selected directions have no computed pairs when opening chart display, the software can prompt you to calculate them immediately.

3D Display and Centering

Directions can be shown in 3D using the variogram display controls.

Useful points:

• Directions are colored by gamma values for quick comparison.
• You can adjust the color table from Edit > Color….
• You can center variogram directions on a chosen centroid/composite location.
• Double-clicking a direction shows additional details for that direction.

Variogram List Menus (What Each Command Does)

File

• Import Pairs…: Load pairs from file.
• Import Variogram…: Load variogram model/component data from file.
• Export Pairs…: Save computed pair data to file.
• Export Variogram…: Save variogram model/component data to file.
• Advanced…: Open advanced variogram options.

Create

• New Experimental Variogram: Create a new variogram container.
• New Direction…: Add one direction manually.
• 13 Magnificent Directions: Add a 13-direction set.
• All Directions In A Plane…: Generate directions inside a selected section.
• By Ellipsoid Axis…: Build directions from ellipsoid orientation.
• Orthogonal directions…: Add two perpendicular directions from a selected main direction.
• Direction Along Hole…: Create along-hole direction settings.

Edit

• Properties…: Edit selected variogram/direction properties.
• Color…: Edit gamma color mapping used in display.
• Components…: Open variogram model component editing.
• Copy…: Duplicate selected items.
• Find And Replace…: Batch update selected entries.

Generate

• Generate Pairs: Compute pairs for selected directions/variograms.

Display

• Set To Centroid: Recenter selected directions on the current centroid.

Chart

• View Experimental Variogram: Open generated chart graphics.
• Chart Properties…: Edit chart/direction visual presentation.

Chart Window

Open the chart window from the variogram tools. The chart window can be docked, moved to another screen, and resized.

Right-click in the chart for quick actions:

• Display Experimental Variogram…: Choose the directions to display (selection must belong to one experimental variogram)
• Properties…: Edit chart and series display (markers, labels, colors, axis options)
• Variogram Type…: Switch display type (including power, covariance, or correlogram variants)
• Add Component…: Add a model component
• Edit Component…: Open/close the component editor panel
• Variable…: Change the variable used by the selected experimental variogram
• Export To Excel… and Copy To Clipboard: Export chart output

Variogram Modeling

Use Edit Component… to create or update the model by adding/removing components.

A common model setup is:

• 1 nugget + 1 exponential, or
• 1 nugget + 2 spherical components

You can still use other combinations when needed.

Interactive Modeling

Interactive component manipulation is available in the chart:

• Keep at least one component in the model (commonly a nugget).
• Use Ctrl + drag on component markers to adjust position (range/sill behavior).
• Right-click on the model curve and use Add Component… to add a component near the selected location.

Automatic Modeling

The component editor includes an Auto fitting option to generate a first-pass model matching the experimental curve. You can then refine manually.

Direction Assistance

When modeling with orthogonal directions, direction-finding tools can help assign component orientation.

Component Types

The following model component types are available (h = distance, C = amplitude/sill parameter, A = distance/range parameter):

• Nugget: V(h) = C
• Linear: V(h) = A·h
• Spherical: V(h) = C·(1.5(h/A) - 0.5(h/A)^3) for h < A, and V(h) = C for h >= A
• Exponential: V(h) = C·(1 - e^(-h/A)) (practical range about 3A)
• Gaussian: V(h) = C·(1 - e^(-(h^2/A^2))) (very low short-distance slope)

Component Parameters

A component can use up to 7 parameters:

• Sill / Variance
• Longest Range
• Intermediate Range
• Shortest Range
• Azimuth
• Dip
• Spin

Parameter availability depends on component type.

Parameter Availability by Type

Isotropic Modeling

With Model isotropically enabled:

• Directional range fields collapse to isotropic behavior (single effective range behavior per component type).
• For isotropic use, tolerance is typically set to 180°.
• Azimuth values of 0° and 180° are effectively equivalent.

Variable-Specific Models

Each variable can have its own model within an experimental variogram context. Models created here are available for kriging workflows.

Lag Distance

Lag can be adjusted dynamically from the stats/ribbon controls:

1. Use Select to choose which directions to update.
2. Enter min/max lag bounds when prompted (precalculation range).
3. Adjust lag with the slider or by entering a value.

The selected directions update to the chosen lag setting.

By default you don’t have to manually set lag distance, as the software calculates it automatically based on the data distribution and displayed variograms.