Pitney Bowes MapInfo Vertical Mapper - Manual (Page 164)

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Vertical Mapper 3.7
The Apply button enables you to recalculate and refresh the semivariogram using new settings.
The graph in the dialog box is a semivariogram of the data and plots variance between sample pairs
on the y-axis and the lag distances for the calculated variances on the x-axis. The experimental
semivariograms that appear in the graph are updated only when you click the Apply button. The
model curves will automatically update when changes that affect the models have been made to the
dialog box. You can modify the visual display of the graph. You can maximize it to full screen by
applying a zoom, or you can undo the zoom. You can also switch from colour to black and white. You
can access these options by right-clicking while the cursor is positioned over the graph.
The bottom portion of the dialog box enables you to modify the model curve so that it better fits the
experimental semivariogram. This is done by applying one or more variogram models to the model
curve.
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• Variogram Model reflects the model that will be applied to the model curve. Seven variogram
models are available: Spherical, Exponential, Gaussian, Power, Hole Effect, Quadratic, and
RQuadratic. Up to six models can be used at any one time.
• Range/Power refers to two different aspects depending on the chosen variogram model. For all
variogram models except power, the value entered refers to the range. This value indicates the
lag distance where the range is considered to begin. If the power variogram model is chosen,
then the value entered is the power coefficient. A power of one yields a linear model. When you
choose multiple models, the range values are summed.
• Sill/Slope refers to two different aspects depending on the chosen variogram model. For all
variogram models except power, the value entered refers to the sill. This value indicates the lag
distance where the sill is considered to begin. If the power variogram model is chosen then the
value entered is the slope of the scale coefficient of the curve. When multiple models are
selected, the sill values are summed.
• Angle reflects the direction in which the variogram model will be applied. The list shows a
selection of different directions that you can use in the semivariogram.
• Anisotropy is the ratio between the range in the minor and major directions of the
semivariogram.