Using Leapfrog’s advanced surfacing editing tools, you have more freedom to shape your model and apply your geological skill and knowledge.
This blog summarises our recent advanced surface editing webinar and gives you access to the full recorded webinar.
The premise for the webinar is that with Leapfrog you use your available geological data to create a base model and then use Leapfrog’s advanced surface editing tools and your skill and knowledge to review and shape the model.The webinar also demonstrates how Central model management can enhance your workflow. In the demonstration, the modeller is asked by a colleague via the Central portal to help with some modelling issues. Within Central she has made an annotation with a particular location for the problem. The modeller is then able to click through to the scene and see the issue. Via Central she launches Leapfrog Geo to access this latest model, work on the problem and later publish and share the revised model. All versions of the models are retained in Central for easy reference and auditing.
FastRBF™, Leapfrog’s secret source
Leapfrog constructs surfaces based on drillhole data and interpreted lines/points using a mathematical algorithm known as a Radial Basis Function (RBF). RBFs are a natural way to interpolate scattered data, particularly when the data points do not lie on a regular grid and when the sampling density varies. This is what makes RBF interpolations ideal for drillhole data. Prior to Leapfrog, RBFs had been successfully used by geo-statisticians, but these solutions were practically limited to a few thousand data points at most. The Leapfrog software suite uses a specially developed interpolation method called FastRBF™. The breakthrough pioneered by Leapfrog, after many years of research by leading mathematicians, was to allow RBFs to be applied to very large data sets.
Combining your skill with the base model
- Once you have used the implicit modelling engine to rapidly build your base model, it’s time to dive in and use your skill and experience to start making interpretations and testing hypotheses.
- What common surface issues do you usually face?
- Intervals aren’t being incorporated into the right surface
- Surfaces aren’t honoring the input data
- Surface is too blobby/bulbous
- Surface extends too far
- Surface doesn’t extend far enough
- Too many disconnected, insignificant volumes are being created.
The webinar uses a typical issue as an example, in this case surfaces expand beyond the local drilling; are quite bulbous and geometrically too large; and don’t honour several intersects. The webinar demonstrates techniques for correcting common surface issues using Leapfrog’s advanced editing options. Considered early in the process, this editing helps solve issues that could arise later.
Editing options presented:
- Adjust surface resolution
- Snap to data
- Intrusion category compositing
- Volume points
- Point generation
- Value clipping
- Trends (e.g. Global and structural)
- Boundary filters
- Add additional data (i.e. polylines, etc.,)
1. Adjust surface resolution
In this webinar a number of options are explained that allow you to adjust the surface resolution. These include choosing a number that’s appropriate for the spacing of your contact points and making modifications to individual surfaces via the Surfacing Tab, such as adding another level of resolution to a vein.
2. Snap to data
Snapping, the capturing of every contact point by force, is by default turned off in Leapfrog. The surface is created on a statistical calculation or a general rating of all of your data points. If you happen to have distinct outliers in your data set they might, when you rigorously snap, force your surface into areas that don’t make sense. Leaving snapping off to begin with gives the statistics the opportunity to look at the whole data set. Surfaces will still try to trend towards outliers but if they’re really far away and don’t make sense in relation to the rest of the data, then the surface will just trend towards it but not capture the data point. Once the base model has been produced you then have the opportunity to look closer and decide if there are any potential issues or structural problems. At this stage you have the option in the Surfacing Tab to decide what data to snap to, for instance it could be all data, or could just be drilling or a customised setting such as to GIS or Polylines.
3. Intrusion category compositing
Automatically, when creating an intrusion surface category compositing is being applied. Under the Compositing tab you have the option to simplify geology by filtering short segments. You have the option to apply rules, depending on the scale you want to apply and the type of unit you are dealing with. Compositing also applies to deposit and erosion surfaces.
4. Volume points and Point generation
Drillhole information is typically introduced into Leapfrog in interval tables that contain From-To intervals and lithology (etc.,) codes, not numeric values. For Leapfrog to understand this information it must first convert the categorical interval data to numeric point data, known as Volume Points, these are automatically generated every time a surface is created in Leapfrog from drillhole data. Once the base model is produced, you are then able to modify these points based on your regional knowledge. The red points have positive (+) values and exist inside the unit of interest; the blue points have negative (-) values and exist outside the unit of interest; the actual contact between two units is a green point with a value of 0; these values represent actual distances away from the contact point along the drilhole trace. Under Surfacing you can choose to change a number of different features, including the Value clipping function.
5. Value clipping function
Within Leapfrog, automatic clipping is applied to give approximately equal weighting to the positive values inside a unit of interest and the negative values outside of that unit, and thus result in a ‘neutral’ surface, that isn’t overly inflated or compressed. You have the option to give these groups, positive or negative, a relative increased value and play with different shapes that fit your scenario much better. Adjusting the value clipping affects the distribution of volume point values and this in turn affects how the surface is interpolated between two known contact points. Adjusting the value clipping influences the volume of the intrusion, as well as it’s continuity.
6. Trends, global and structural
Amongst the most powerful and useful surface editing tools in Leapfrog are the global and structural trends. The webinar demonstrates a structural trend from a mesh previously created and shows how to apply the strength, range and trend to the surface which is then rebuilt taking it into account. These tools allow you to control and refine the orientation and continuity of surfaces and volumes in Leapfrog.
7. Add additional data and boundary filters
Numerous data types can be easily incorporated into a single surface. The webinar shows you how to build undersurface chronology with drillholes initially and then incorporate any available point data, structural data, and/or mapped contacts in the form of GIS or polylines.
Finally, the webinar considers a scenario in which an intrusion has been emplaced post-faulting and therefore shouldn’t exhibit any offset. By controlling the boundary filter settings in Leapfrog, the 2 surfaces on either side of the fault can connect with each other by allowing each fault block to honour the data on the other side of the fault. Using this process, you don’t have to restructure your surface with polylines to capture the other side.
Not a Leapfrog Geo user? Watch this 15 minute demonstration to see an overview of what it’s capable of.