RockWorks | Utilities | Grid | Filters | Limit
This Utilities filter is used to compare the z-value of each node of an existing grid model to the corresponding node in another ("comparison") grid model, and to re-assign low or high nodes to the values in the comparison grid. In this manner, you can, for example, constrain a stratigraphic surface to another stratigraphic layer, or to the ground surface. You can invoke either a low-stop or a high-stop filter.
! This tool requires that both grid models already exist and that they have the same dimensions and node spacing (use Grid | Statistics | Report if you need to check their dimensions). See Resampling Grid Models if you need to re-dimension an .RwGrd file.
Menu Options
Step-by-Step Summary
Menu Options
- Input Columns: If you request plotting of 2D map symbols (below) AND if you have data loaded into the RockWorks Utilities datasheet, you can use these prompts (along the left edge of the Options window) to specify the X and Y locations for the map symbols. If you don't plot map symbols, these will be ignored.
- X (Easting): Click here to select the name of the column containing the X or Easting coordinates.
- Y (Northing): Click here to select the name of the column containing the Y or Northing coordinates.
- Input: Expand this heading if necessary, to specify the two input grid models.
- Grid "A": Click to the right to browse for the name of the grid model (.RwGrd file) to be filtered.
- Grid "B": Click to browse for the name of the other grid model, which will serve as the reference (limit) filter.
- Output: Expand this as necessary to enter a name for the output model.
- Grid "C": Click to type in a name for the new grid file that will be created.
- Filter Type: Choose one of the following:
- High-Stop/Low Pass: Choose this option if you want to "stop" high Z values in Grid A: Any nodes in Grid A with Z-values that exceed the Z-values of corresponding nodes in Grid B will be replaced with Grid B's Z-values. Grid A nodes that are lesser in value than those in Grid B will pass unchanged. This could be used to constrain a stratigraphic surface with the ground surface. (See the left-hand picture, above.)
- Low-Stop/High-Pass: Choose this option if you want to "stop" low Z values in Grid A. Any nodes in Grid A with Z-values that are less than the Z-values of corresponding nodes in Grid B will be replaced with Grid B's Z-values. Grid A nodes that exceed those in Grid B will pass unchanged. This could be used to erode an upper surface against a lower surface. (See the right-hand picture above.)
- Create 2-Dimensional Grid Diagram: Insert a check in this check-box if you want to display the output grid as a 2D map at this time. Expand this heading to set up the 2D map layers (bitmap, symbols, labels, line contours, color-filled contours, labeled cells, and/or map border).
- Create 3-Dimensional Grid Diagram: Insert a check in this check-box if you want to display the output grid as a 3D surface. Expand this heading to set up the 3D map layers (flat surface, Boolean colors, perimeter, reference cage). You can request both a 2D and 3D representation of the grid model.
- Create Grid Statistics Report: Insert a check here if you want to see a report summarizing the output grid.
- Include Standard Deviation: Check this box if you want the report to include standard deviation.
- Include Directional Analysis: Check this box to include slope, aspect, and strike computations. Be warned that these can take a few moments for large grid models.
Step-by-Step Summary
- Be sure you have two real number RockWorks grid models already created, for input into this program. Be sure, also, that they have the same dimensions and node counts.
- Access the RockWorks Utilities program tab so that the Grid menu is visible.
- If you'll be creating a 2D map with sample location (well) symbols, you can use the File | Open option to open the .RwDat file containing the X and Y location coordinates for the map symbols.
- Select the Grid | Filters | Limit menu option.
- Enter the requested menu settings, described above.
- Click the Process button to continue.
The program will read the Z values in reference Grid B. It will then read each corresponding node value in source Grid A and compare. Node values that exceed Grid B's will be re-assigned Grid B's values (if High-Stop was selected). Grid A node values that are less than those in Grid B will be assigned Grid B's values, if Low-Stop was selected. The resulting model will be stored on disk 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. If you requested a statistics report, it will be displayed in a Text 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 diagram(s).
! Each time you click the Process button, the existing display(s) will be replaced.
- View / save / manipulate / export / print the diagram in the RockPlot2D or RockPlot3D window.
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