Wireframe Modelling

Mining technology


* Studio 3 Wireframe Modelling Introduction
Studio 3 provides a fully comprehensive and interactive three dimensional system for creating, modifying, merging, intersecting, displaying and evaluating both solid models and Digital Terrain Models (DTMs).

Strings may be linked using 'point and click' selection methods and a choice of linking algorithms is included. The optimized method frequently allows even highly complex strings to be linked automatically without point tagging; however, tagging is also provided for greater control over linking.

Endlink, unlink, slice and evaluation (both volumetric and against a cell model) are also supplied. DTMs may be constructed from a set of points and strings, and linking constrained to lie within user-defined limits.

Studio 3 has the facility to turn wireframe models into cell and sub-cell models in a single pass with the amount of cell sub-division under user control. This unifies the concepts of wireframe and cell models, allowing varying grades within seams and orebodies to be represented in as much detail as required.

Studio 3 has updated algorithms for wireframe boolean operations:

* Union
* Merge
* Difference
* Intersection
* Split
* Extract
* Decimate etc.

Operations work on objects and create new objects as a result of the operation. Selection methods are based on attributes and/or filter expressions.


* Modeling Using Perimeters
A geological interpretation consists of section or plan drawings showing structure and mineral boundaries. These can be created directly within Datamine Studio using drillhole information and interactive graphics or by hand over hardcopy plots which you can later digitize.

As you digitize strings you should assign them codes or attributes to distinguish the different zones and rocktypes. Datamine can later assign these attributes to the cells created in the block model. Examples of attribute fields include Color, ZONE or Rocktype, or any other item you find necessary to describe the geology.

Using interactive graphics, perimeter points can be placed at the precise three-dimensional coordinates of selected drillhole intervals. DATAMINE calls this automatic positioning of points on existing screen objects snapping. For Datamine to fill the strings with cells they must form closed areas or perimeters. Ensure that adjacent boundaries abut up against each other with no gaps or overlaps. You can use interactive string utilities to automatically generate outlines from open overlapping strings. In this way common boundaries need to be digitized only once.


* Filling Perimeters
Perimeter filling requires that the perimeters be planar and lie in the 'XY', 'XZ' or 'YZ' plane. If the perimeters do not meet any of these conditions, you Will need to use wireframe modeling.

The process creates cells within the perimeter, perpendicular to the perimeters at a user defined projection distance either side of the perimeter. Typically this projection distance is set to half the section spacing and care needs to be taken to ensure that the values you use do not create gaps or overlapping cells between the sections.

The results will also be better if you closely space your sections and the geological structure lies

approximately along an orthogonal axis. Otherwise the model created may appear 'blocky' and a poor fit to the actual geology.


* Wireframe Modeling Modeling Using Wireframes
The most precise way to define a geological boundary in three-dimensions is with a wireframed surface or wireframed solid. Both are essentially the same except that wireframe solids enclose a volume while a wireframe surface is normally open. They may also differ in the techniques employed to create them. The use of wireframes, while giving more precision than perimeters, will require a thorough knowledge of how the deposit behaves in three-dimensions. The starting point for solid wireframe modeling is usually a series of perimeters outlining the geology. These perimeters need not be planar and may lie at any orientation. They must not however overlap in three dimensions with themselves (forming a knot or 'twisted bowtie' shape) or with adjacent perimeters.

Wireframe Concepts

Wireframes are defined on the basis of :

* GROUP: a GROUP can consist of one or more distinct wireframes which have either the same surface identifier, or different surface identifier.
* SURFACE: an individual wireframe SURFACE can be selected from within aGROUP of wireframes. This surface can be either a DTM or a solid wireframe.
* LINK: each wireframe surface consists of a number of individual links.

This classification of wireframe GROUP and SURFACE provides a means by which wireframes can be identified for operations such as combining and verifying wireframes which will be outlined later. It also provides greater control when using the ‘erase’ commands. You can erase GROUPs, SURFACEs, LINKs and individual triangles. The wireframe group, surface and link identifiers are stored in the wireframe point and triangle files as field GROUP, SURFACE and LINK respectively. These values are assigned internally by the system. It is possible to select wireframe data based on group and/or surface number.


* String Linking
String linking is a technique used to “link” closed perimeters together to form a solid volume. There are three linking algorithms used in Datamine which can be used depending on the nature and complexity of the perimeters.

* MINIMUM AREA - The system will create the triangulation which has the smallest wireframe surface area.
* EQUAL ANGLES - The system will create equi-angular triangles (i.e. equilateral or isosceles triangles).
* PROPORTIONAL LENGTH - This option will create triangles which best maintain their proportional position along the string. The starting edge for triangulation is determined either by user defined tag strings or, if selected by the system, the closest pair of points on the two strings. This option works best where the shape of the two strings is similar.

Wireframe advantages

Besides allowing you to build more precise models wireframes 0ffer other advantages over perimeters.These advantages include:

* You can slice wireframes and plot the slices in any plane.
* Your wireframe slices can also be converted to strings. This allows you to do your interpretation in one plane, wireframe the results and then create a new set of perimeters in a new orientation.
* You can very quickly calculate accurate volumes.
* They offer the clearest and most graphic way to display your designs to other people.


* Terrain Modelling
A Digital Terrain Model (DTM) is used to model surfaces representing topography or geological structures such as seams or faults.

You can create a DTM from contour strings or point data, or both combined.

See the images on the right for examples of DTM creation in Studio 3.


* Combining and Splitting Wireframes - Boolean Operations
The following Studio 3 commands represent some of the available commands that can be used to manipulate wireframe models:

* Merge/Split - This command will split two wireframes where they intersect and can be used for both open and closed wireframes.
* Solid-Union - The SOLID-UNION command allows you to combine wireframes
* Solid-Difference - The SOLID-DIFFERENCE command allows you to intersect two overlapping wireframes and update the first wireframe selected minus the overlap from the second wireframe selected.
* Solid-Intersection - The SOLID-INTERSECTION command can be used to find the common volume of two overlapping wireframes. The resultant wireframe represents the overlap of the two selected wireframes.
* Solid - Split at Plane - The SPLIT AT PLANE command can be used to split a wireframe along the intersection of the selected wireframe(s) with the current view plane.
* Solid - Multiple Split - The MULTIPLE SPLIT command is used to split a wireframe at regular intervals parallel to the viewplane. You must defined the interval used for splitting.
* DTM – Update - The DTM-UPDATE command is used to update one surface wireframe with another. The new surface is generated using the second wireframe selected to update the surface elevation.