
RockWorks | ModOps | Grid | Filters | Boolean Sieve
This program reads multiple Boolean grid models, "overlays" them to compare node values, and generates a final output Boolean grid in which nodes are assigned a value of "1" or "0" based on an "AND" or an "OR" filter, as you define. This is a quick means for comparing multiple true/false models to see where any nodes or all nodes meet your criteria.
! In order for the program to match up corresponding nodes in the input grid files, they ALL must have the same dimensions (X and Y coordinates and range) and numbers of nodes.
See Applying a Boolean Filter to a Grid Model for instructions for creating the true/false models.
Menu Options
Step-by-Step Summary
- Filter Options
- Output Grid: Click to the right to type in the name to assign to the new grid file (.RwGrd) that the program will create, which results from comparing the input grid models.
- File Name Column: Select the name of the column in the current datasheet where the names of the input Boolean grid models are listed.
- Type of Operation
- Node = True if All Nodes at Same XY are True (Boolean AND Filter): Choose this option if the output nodes are assigned a value of "1" where all nodes in the input files have a value of "1" (= "true"), and a value of "0" where any nodes in the input grids are "0" (= "false").
- Node = True if Any Node at Same XY is True (Boolean OR Filter): Choose this option if the output nodes are assigned a value of "1" where any node in the input files have a value of "1" (= "true"), and a value of "0" where all nodes in the input grids are "0" (= "false").
- Null Processing: Use these settings to define how nodes with null values are to be processed.
- Result Always Null: Choose this if the output should be Null if the corresponding node in any of the input files is Null.
- Result Always...: Choose this if the output should be assigned a user-entered value if the corresponding node in any of the input files is Null.
- Treat Nulls as "0" Value: Choose this option if Null values are to be considered as "0" values in the intput grids.
- Treat Nulls as "1" Value: Choose this option if Null values are to be considered as "1" values in the input grids.
- Treat Nulls as...: Choose this option if Null values are to be considered as a user-entered value in the input grids.
- 2D Grid Map
Check this box to display the output grid as a 2D map at this time.
Click this tab to set up the 2D map layers (bitmap, symbols, labels, line contours, color-filled contours, labeled cells, map border, etc.).
!You'll probably want to invoke a Boolean color scheme if you turn on color-filled contours.
- 3D Grid Diagram
Check this box to display the output grid as a 3D surface at this time.
Click this tab to set up the 3D map layers (surface colors, images, reference cage, etc.).
! Boolean surfaces in 3D won't make much sense unless you display them a Flat Surfaces.
! You can request both a 2D and 3D representation of the grid model.
- Be sure you have two or more Boolean grid models (.RwGrd files) already created, for input into this program.
- Click on the RockWorks Datasheet program tab.
- Open or create a datasheet in which the names of the existing Boolean grid models to be compared are listed. Here is a very simple example of how this datasheet might look:

- Select the ModOps | Grid | Filters | Boolean Sieve menu option.
- Enter the requested menu settings, described above.
- Click the Process button to continue.
The program will load each input grid file, compare each node to the corresponding node in the other input files. It will generate an output grid with "0", "1" and Null value designations as you requested. The resulting model will be stored in the project folder under the output grid file name.
The requested diagram(s) will be displayed in a RockPlot2D tab and/or RockPlot3D tab in the Options window.
- You can adjust any of the settings in the Options window and then click the Process button again to regenerate the grid and diagram(s).
- View / save / manipulate / export / print the diagram in the RockPlot2D or RockPlot3D window.
Tips: Since Boolean models contain only two node values, be sure to choose the "Logical" color scheme if you're creating 2D color-interval maps. For both 2D and 2D color-filled maps, you can also create a custom color table where you define the colors to be used for display of the 0 - 0.5 and 0.5 - 1 node values.
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