gridding and horizons
The gridding and horizons module uses data files containing geologic horizons or surfaces (usually .geo, .gmf, and other ctech formats) to model the surfaces bounding geologic layers that provide the framework for three-dimensional geologic modeling and parameter estimation. Conversion of scattered points to surfaces uses kriging (default), spline, IDW, or nearest neighbor algorithms.
gridding and horizons creates a 2D grid containing one or more elevations at each node. Each elevation represents a geologic surface at that point in space. The output can be sent to 3d estimation, horizons to 3d, horizons to 3d structured, surfaces from horizons, and other modules.
The module can produce layer surfaces within the convex hull of the data domain, within a rectilinear domain with equally spaced nodes, or within a rectilinear domain with specified cell sizes such as a finite-difference model grid. The finite-difference gridding capability allows the user to visually design a grid with variable spacing, then krige the geologic layer elevations directly to the finite-difference grid nodes.
gridding and horizons also has the ability to read .apdv, .aidv, and .pgf files to create a single geologic layer model. When such a file is read, the module interprets it as geology as follows: if top-of-boring elevations are provided, they define the ground surface; otherwise, the highest sample elevation in each boring is used. The bottom surface is created as a flat surface slightly below the lowest sample in the file.
Ports
| Direction | Name | Type | Description |
|---|---|---|---|
| Input | Input Filename | String | File used to generate the stratigraphic surfaces. |
| Output | Output Filename | String | File used to generate the stratigraphic surfaces. |
| Output | Output Geologic Field | Field | The main geologic field output from the module. |
| Output | Geologic Legend Information | Geology Legend | Information required to properly label stratigraphic output or lithology within Legend. |
| Output | Geology Export Output | Vistas Data | Information required for direct exporting of geology to other software. |
| Output | Status Information | String | Text containing the full status information output from the module. |
| Output | Output Object | Renderable | A renderable object displaying the grid and variography created by the module. Output even when Allow Run is off. |
| Output | Stratigraphic Grid Data | Realization | Information required for direct exporting of stratigraphic grid data. |
Properties
| Property | Type | Description |
|---|---|---|
| Allow Run | Boolean | Determines whether the module is allowed to execute. Set to True to allow this module to run. |
| Filename | File | The file containing geology data to interpolate to the created grid. |
| Execute | Button | Accepts all values and performs interpolation. If clicked and the application saved, the module will run when the application is loaded. |
| Z Scale | Double | The vertical exaggeration to apply to the display objects. |
Grid Settings
| Property | Type | Description |
|---|---|---|
| Grid Type | Choice: Rectilinear, Convex Hull, Finite Difference | Defines the nature of the domain that will be kriged. Rectilinear produces a model within a user-specified rectangular domain. Convex Hull produces a model with an irregular boundary defined by the distribution of measured data points. Finite Difference kriges geologic layer elevations directly to finite-difference grid node locations. |
| Only Create Grid | Boolean | Forces the module to exit after gridding is complete with no interpolation performed. |
| Grid Origin | Coordinates | Sets the minimum coordinate domain in which kriging of geologic surfaces will be completed. Values default to the minimum of the file data when the module runs. |
| Grid Maximum Extents | Coordinates | Sets the maximum coordinate domain in which kriging of geologic surfaces will be completed. Disabled for Finite Difference gridding. |
| X Resolution | Integer | The number of grid nodes in the model’s X domain. |
| Y Resolution | Integer | The number of grid nodes in the model’s Y domain. |
| Boundary Offset | Double | Sets the distance that the convex hull for the kriging domain will be set outside of the actual convex hull of the data, allowing extrapolation beyond the actual data. |
| Grid Rotation | Double | Rotates a finite-difference grid around the Min X, Min Y point. |
| Finite Difference Grid | Finite Difference Grid | Allows creation of a model broken into regions with varying cell sizes. Each region can have any number of cells with sizes that vary using an initial cell size, cells to add, and a cell size change factor. |
| Display Grid | Boolean | Displays the grid in the output renderable port. |
Krig Settings
| Property | Type | Description |
|---|---|---|
| Reach | Double | The radial distance from any given model node that the module will look for data points. Setting to 0 causes the module to calculate a reach approximately two-thirds of the longest distance between any two data points. |
| Points In Reach | Integer | The maximum number of data points within the reach to consider for parameter estimation at a model node. |
| Quadrant Search | Boolean | Changes the method by which data sample points are selected. When on, searching is performed for each of the four quadrants surrounding the point to be kriged. |
| Use All Data | Boolean | Causes all data points to be used when kriging, not just those within the reach. Provides the smoothest surfaces and can be faster in some cases. |
| Max Points For Use All Data | Integer | Provides a cap for large models. If the number of points in the file exceeds this cap, the reach/points method will be used instead. |
| Estimate In Thickness Space | Boolean | Used for .geo files. When on, surfaces cannot rise above the surfaces above them unless flagged as pinched values. When off, pinch flags are ignored and each surface is kriged independently. |
| Bottom In Thickness Space | Boolean | Causes the last horizon to be treated in thickness space as well as the middle horizons. |
| Pinch Factor | Double | Controls where pinching occurs between positive thicknesses and borings with the pinch flag. The default of 1.0 causes pinching to occur approximately halfway between positive thicknesses and pinch-flagged borings. |
| Points In Pinch | Integer | Determines how many of the nearest points will be used to determine the estimated thickness at the pinch flag location. |
| Use Gradients | Boolean | Used with Natural Neighbor interpolation. When on, gradients estimated at sample points improve the interpolation result. |
| Estimation Method | Choice: Kriging, Spline, IDW (Shepard), IDW (Franke/Nielson), Nearest Neighbor, FastRBF, Natural Neighbors | The method for interpolating data onto the created grid. |
| Variogram And Anisotropy | Variogram | Controls the semi-variogram model and 2D anisotropy settings for kriging. |
Computational Settings
| Property | Type | Description |
|---|---|---|
| Computational Surface Type | Choice: None, Heading-Dip Plane, Elevation, Depth | Selects the type of computational surface to add to the output. A computational surface should be created after the initial gridding is complete. |
| Include Surface | Boolean | Allows a user-selected surface from the file to be included in the output. |
| Include Surface Number | Integer | Sets which surface number to include when Include Surface is selected. |
| Surface Position | Choice: Include Above, Include Below | Specifies whether the included surface is above or below the computational surface. |
| Heading Dip Value | Heading/Dip | The heading and dip values used to align the computational surface when Heading-Dip Plane is selected. |
| Elevation | Double | The elevation to translate the heading-dip plane by. |
| Anchor Point | Coordinates | The anchor point values to translate the heading-dip plane by. |
| Material ID | Integer | The material ID for the generated surface when using Heading-Dip Plane. |
| Surface Name | String | The surface name for the generated surface when using Heading-Dip Plane. |
| Elevation Surfaces | Elevation Surfaces | Defines computational surfaces based on set elevations. Each surface specifies an elevation, material number, and surface name. |
| Depth From | Choice: Top, Surface Number, Bottom | The method for determining the starting elevation from which each depth is measured. |
| Surface Number | Integer | The surface number to compute depths from when Depth From is set to Surface Number. |
| Depth Layers | Depth Layers | Defines computational layers based on depth from the selected surface. Each layer specifies a depth, material number, and layer name. |
Variography Display
| Property | Type | Description |
|---|---|---|
| Display Variogram Ellipse | Boolean | Displays the variography ellipse in the viewport. |
| Ellipse Opacity | Double | Sets the opacity of the ellipse. |
| Resolution | Integer | The resolution of the ellipse. Larger numbers create more detailed representations. |
| Ellipse Scale | Double | Scales the ellipse equally along each axis. |
| X Offset | Double | Translates the ellipse along the x axis. |
| Y Offset | Double | Translates the ellipse along the y axis. |
| Z Offset | Double | Translates the ellipse along the z axis. |
| Ellipse Color | Color | The color of the variogram ellipse. |
| Display Variogram Lines | Boolean | Displays lines aligned with the variography ellipse. |
| Line Scale | Double | A scalar that sets the length of the variogram lines relative to the scale of the ellipse. |
| Primary Ratio Color | Color | The color of the primary ratio axis line. |
| Secondary Ratio Color | Color | The color of the secondary ratio axis line. |