Mask Multiple

Use the Mask Multiple option to mask many grids at one time. This option can be used on an entire grid model or varying layers.

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Instructions

On the Grid Calc menu, point to Model, and then click Mask Multiple to display the Mask Multiple panel.

Masking Parameters

Design DB

Use this section of the panel if you want to create the mask from polygons. You will need to specify the name of the design database that contains the polygons. Leave this field blank to use the currently open design database.

Layer

Specify the name of the layer that contains the polygons. Wildcards (* multiple character and % single character) can be used.

Object

Specify the name of the polygons. Wildcards (* multiple character and % single character) can be used. Values inside clockwise polygons are visible, values inside anticlockwise polygons are masked (invisible).

Mask area name

Use this option to mask the grid with the area mask file (<proj><area>.msk). Specify the area name of the mask file.

Grid

Use this option to mask the buffered grid with the mask of another grid. Specify the name of the grid. This option is node based.

Equation

Use this option to use a logical expression to delineate masked and non-masked areas of the grid. A logical expression is one that evaluates to zero (false) or non-zero (true). This option is node based.

Distance from point

Use this option to mask all grid cells greater than the specified distance from loaded data points. This option is node based.

Replace

Select this check box to remove the current grid mask and replace it with the new mask.

Area Mask

Select this option to mask the four nodes that make up the grid cell if 50% of the cell area is included in the polygon. The cell is unmasked if more than 50% of the area is excluded by the polygon. The entire cell is taken into account. This option is the only method that considers a cell rather than individual nodes.

Point in Polygon

Select this option to mask a node if it is inside the polygon. Nodes outside the polygon are unmasked. Like masking from a grid, individual nodes are considered independent of the surrounding nodes.

Save Parameters

Window

Enter values for the minimum (x, y) and maximum (X, Y) Eastings and Northings. These values will define the four corners of the grid.

Grid size

Enter the size of the grid cell. Although, there are no software limits on the number of cells in the grid, obviously speed of operation may suffer when using a large number of cells.

Advanced

Spline

Select this check box to use the geographical window associated with the active specifications.

Fault/No fault

Specify whether or not to include the current fault strings.

Click OK.

The masks are then applied.