Balanced Shapes using the Intrusion Tool
What methods do folks find best to generate "balanced shapes" when using the Intrusion tool.
An example being a narrow Intrusion shape (with an 65deg inclined structural trend applied) that has a limiting exterior point on one side from an adjacent drillhole, but unconstrained on the other side. Left to run freely the shape would be shorter on the limiting side and reach the Interpolant range extent on the opposite side.
The consequences in the model is although the shape may be representative in orientation, it may be over predictive away from drilling for some applications.
Various discussions with users have included adjusting the Value Clipping where the Mean = 0; create a distance filter on the drilling to limit the boundary, open up the Point Generation Offset Distance to promote connectivity.
I am thinking the challenge here is the steep & narrow geological reality of the features. The Tips for intrusion modelling, and advanced surface editing in Leapfrog Geo video did not cover some of the more prescriptive point generation and value clipping edit tools so Id be curious how folks have successfully applied this as well.
50m thick slice
Comments
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Graham,
I've had exactly the same problems with using Intrusion modelling on narrower intercepts and after exhausting the options you mentioned have resorted to manually digitising points to force a continuation of the shape and avoid holes. Ultimately I have to then ask myself whether Intrusion modelling is the most suitable way of representing the geometry of mineralisation, or if I should be using vein and/or vein system models.
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Thanks James.
I have seen the vein tool used as well, much of the feedback I have heard is it is a very prescriptive method and extremally time intensive + project bloating exercise. Where in contrast the the Intrusion tool (after tuning parameters) is a data forward tool.
However, I have found the Leapfrog support documentation not very linear. It explains how each many of the parameter works (e.g. Interpolating Settings, Structural Trends, Clipping Values, Compositing…), but it never ties together and explains how they all work together to control the spatial extents and volume of the produced wireframe.
In the image posted I can convince myself the the package of volumes are "balanced" and I am ok with this given exterior points (blue) are pushing back on shape and the geological verification from core logs/photos. But my cautions are in the occurrence of the right most volume where there is a small tip above the drillhole, and then a overly predictive volume modeled below the drillhole. Where in my minds-eye I would like the shape to look like the volume in the top right where the volume is more or less "balanced" across the drilling - 50% toward the adjacent drilling and ~50% away from the drilling.
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Agree 100% Graham, especially regarding the documentation. I'm not sure I agree with vein modelling being any more time intensive than other methods when you start taking into account having to manually digitise explicit polylines or points to control say intrusion contacts. Your example of the 'unbalanced' right-most shape seems to highlight the difficulty any interpolation technique has when projecting into a region of no data.
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