Modifying the Model’s Boundary
Geological models and interpolants are created with a basic set of rectangular extents that can then be refined using other data in the project. These extents usually correspond to the ground surface and known boundaries. Creating extents can also be used to restrict modelling to a particular area of interest; for example, modelling can be restricted to a known distance from drillholes by applying a distance function as a lateral extent. Extents do not need to be strictly vertical surfaces, and can be model volumes. For geological models, it is also possible to define a base that serves as the model’s lower boundary.
When a topography is defined for the project, it will be automatically applied as a geological model’s upper boundary when the model is created. This is not the case for interpolants, and so if you wish to use the topography as the upper boundary, double-click on the interpolant in the project tree and tick Use topography in the Boundary tab.
To create an extent, expand the model in the project tree. Right-click on the Boundary object and select from the New Lateral Extent or New Base options. Follow the prompts to create the extent, which will then appear in the project tree under the model’s Boundary object. For example, this geological model has two lateral extents, one from a polyline and the other from GIS data:
Creating extents using the different types of data is described in further detail in the following topics:
- Extent from a Model Volume
- Extent from a Polyline
- Extent from GIS Vector Data
- Extent from Points Data
- Extent from Structural Data
- Extent from a Surface
- Extent from a Distance to Points
- Extent from a Distance Function
- Base from Lithology Contacts
New extents are automatically applied to the boundary being modified. Leapfrog Geo usually orients a new extent correctly, with red presenting the inside face of the extent and blue representing the outside face. If this is not the case, you can change the orientation by right-clicking on the extent in the project tree and selecting Swap Inside.
If you have defined an extent and want to remove it from the model, there are two options. The first is to right-click on the extent in the project tree and click Delete. This deletes the extent from the model, but does not delete parent objects from the project unless they were created as part of the model, e.g. a polyline used as a lateral extent but not shared within the project. Use this option only if you are sure you do not want to use the extent.
The second method is useful if you are making changes to the extent and do not want to recompute the model with each change. Double-click on the model’s Boundary object or double-click on the model and click on the Boundary tab. The Boundaries part of the window lists all objects used as extents for a geological model:
Untick the box for extents to temporarily disable them in the model. The model will be reprocessed, but you can then work on the extent without reprocessing the model. Disabled extents will be marked as inactive in the project tree: