Category: How-to

Leapfrog’s structural trend

By Peter Joynt

It is not often in geology that mineralisation or geological units behave in a consistent planar fashion. The earlier article on interpolation and anisotropy by Kirk Spragg outlined a detailed explanation of Leapfrog’s global trend and how it affects the interpolation of points. This article aims to give users an introduction to the application of structural trends and how they can be applied to a model to handle different situations.

What is a Structural Trend?

A structural trend is a generalisation of the global trend that allows changes in direction of continuity over a defined surface. Instead of being based on a plane like the global trend with the user defining the ellipsoid ratios, the structural trend is based on a surface. This surface can be any shape or orientation usually defined by geological constraints such as faulting, foliation etc. The surface is then effectively down sampled to determine the local trend at each point on the mesh to give the user an anisotropy that varies throughout the defined space. This makes the structural trend perfect for geological units or mineralisation that is not planar. The structural trend does not determine the final surface; this is still done by the interpolant and the data points used. In Leapfrog the default interpolant type is isotropic, which lets us more easily visualise trends that are often hard to pick up when looking at raw data. Figures 1, 2 and 3 show the difference between an isotropic interpolant, global trend and a structural trend.

Isotropic interpolant modeled in Leapgfrog software.

Figure 1: Isotropic interpolant

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Building a geological model – Part 3 of 3

By Andrew Cantwell

Creating a first pass interpolant

This video continues on from part 2 of building a geological model in Leapfrog.

The process outlined in this video is simplified – the idea of this blog post is to give an understanding of the speed and ease of creating a first pass interpolant which can then be refined to give a more reasonable model.

You won’t hear any narration in this video but captions have been provided to explain the basic steps. If you’re after a more detailed description of the model building process then please contact your local support team.

We recommend you view this video in full screen mode. It may take approximately 30 seconds after you press play to switch to High Definition (given your internet connection allows it).

The main steps in this video include:

  • Viewing the assay data
  • Using some of the visualisation options to gain a basic understanding of the trend
  • Creating an interpolant model
  • Adjusting some basic parameters to get a more realistic model.

If you missed the previous videos in the model building series you can view Part 1 or Part 2 on this blog.

 

Further reading:
Case Study – can implicit modelling be used to model complex geology.

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Building a geological model – Part 2 of 3

By Andrew Cantwell

This video continues on from part 1 of building a geological model in Leapfrog.

You won’t hear any narration in this video but captions have been provided to explain the basic steps. If you’re after a more detailed description of the model building process then please contact your local support team.

We recommend you view this video in full screen mode. It may take approximately 30 seconds after you press play to switch to High Definition (given your internet connection allows it)

The main steps in this video on building a geological model include:

  • How to create a new geological model
  • Creating depositional surfaces
  • Editing a surface using a polyline
  • Activating surfaces to produce volumes
  • Creating dykes
  • Editing interval selections
  • Adjusting the chronological order of the surfaces
  • Creating intrusions

If you missed part 1 you can view the post here

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Video: Importing and manipulating data – Building a geological model in Leapfrog Geo – Part 1 of 3

By Andrew Cantwell

This video provides a short and simple introduction to importing data into Leapfrog, as well as manipulating the data to make it easier to model. It is the first video in a series of 3 that will be posted on our blog over the next couple of weeks. The video provides captions to explain the basic steps but does not include any narration or detailed description of the entire model building process which is covered in Leapfrog Geo Fundamentals training.

The main steps in this video about importing and manipulating the data include:

  • Importing drillholes
  • Selecting columns for import
  • Fixing errors in the drilling
  • Importing the topography points
  • Creating a topography & adjusting the resolution
  • Simplifying the geology by creating a grouped column
  • Using the interval selection tool to select intervals which can be split up

Part 2 of this video series is available here

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Grade shells vs. mineralised zones

By Lisa Swinnard

There is more than one way to create a boundary surrounding a cut-off grade in Leapfrog; however the different techniques used to create these boundaries rely on different underlying concepts. Which tool to select will depend on the ultimate purpose for building the boundaries.

The typical way to create these boundaries is by building grade shells using the Interpolant tool in Leapfrog. Interpolated grade shells are built by using the known drillhole or point data to interpolate values infinitely across the boundary extents; isosurfaces (grade shells) are then created to link up identical values. Grade shells created by interpolation represent a “soft boundary”, as it is not possible to snap these isosurfaces (grade shells) to contact points on drillholes. Grade shells created using interpolation are ideal tools for exploration drillhole targeting.

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Making a scene – Leapfrog Saved Scene

By Sam Bain

Imagine you have built an amazing geological model. You have identified and fixed the problems in the core logging, you have reconciled the lithology labels used by the different historical surveys of the area, your geological surfaces are consistent with the data and make geological sense, your grade model has been built taking into account the geological structures and you are happy with its predictions. Is that your job done? No, of course not.

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Interpolation and anisotropy

By Kirk Spragg

Introduction

In addition to interpolation, Leapfrog provides two tools that give the user control over the continuity of grade in their interpolants. These are the “Global Trend” and the more advanced “Structural Trend”.

The Global Trend can be effectively used to alter the results of an interpolant.  The Global Trend  is suitable to use in situations where the underlying geology implies that grade is continuous in a planar direction over large distances. If this is not the case, and the underlying geology implies that direction of grade continuity varies over space, then Leapfrog’s Structural Trend is a more appropriate tool to use when modelling your deposit or ore body.

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Viewing multiple images projected on topography

By Sam Bain

Leapfrog allows users to import a range of images into a project so they can be viewed on topography. These include but are not limited to topographic maps, satellite imagery, aerial photos, and geological maps.

Imported images can be viewed projected on topography by adding the topography to the scene and then selecting them from the GIS data drop-down box below the topography object in the shape list (Figure 1).

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Modifying your drillhole data: Interval Selections

By Sam Bain

The “Interval Selection” tool in Leapfrog combines most of the abilities of Grouping and Splitting (as discussed in previous blogs) with fewer restrictions. The Grouping and Splitting tools provide workflows for combining or splitting existing lithologies exclusively. The intervals selection is ideal when elements of both the grouping and splitting workflows need to be combined. For example, perhaps assay data indicates some intervals have been incorrectly logged and need to be assigned to a new lithology. If these intervals have been logged as several different lithologies then they need to be split from their old lithologies and then grouped to a single new lithology. The interval selection tool allows you to do this.

Figure 1: Right click the interval table and select the "Interval Selection" option

Figure 1: Right click the interval table and select the “Interval Selection” option

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Modifying your drillhole data: Splitting lithologies

By Sam Bain

The “Split Lithology” tool (available in Leapfrog Geo, Geothermal, and Hydro) creates a new lithology column by sub-dividing lithologies in an imported column. Often simple logging will result in repeating intervals on each drillhole and these will need to be separated for modelling purposes. As an example, perhaps three unique limestone units at different depths are encountered by exploratory drilling. These might all be logged simply as “Limestone”. In this case the splitting tool could be used to divide the “Limestone” intervals into “Upper”, “Middle”, and “Lower” units. Then each unit can be modelled separately. It is important to note that the original logged intervals are preserved, and the new splits are made in a new interval column. The modeller can correct or re-interpret the logging without altering the original field data.

This blog explains how the “Split Lithology” tool works by walking through a simple example.

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