overburden
The overburden module computes the complete volume required to excavate a plume or ore body given the pit wall slope (measured from vertical) and the excavation digging accuracy (referred to as buffer size).
overburden receives any 3D field into its input port and outputs the same field with an additional data component. It computes a new data component based on the nodal values in the 3D field and two user-defined parameter values called Wall Slope and Buffer Size. The data component is subset according to a concentration input (based on the subsetting level you want excavated). For example, once overburden has been run for GOLD at a 45 degree pit wall slope, the user would select the overburden data component and subset all data below 1 ppm to render a 45 degree slope pit which would excavate everything higher than 1 ppm concentration. A volumetrics calculation could be made on these criteria which would encompass the excavation and the ore body above 1 ppm.
overburden creates a data component name that includes the wall slope, module name, and original data component (analyte) name.
The overburden data component may be subset by modules such as plume, isosurface, or plume shell.
Notes:
- It is much safer and more understandable to work at Z Scale = 1. Otherwise, the apparent angle of your pit will be very different than the input angle. As the Z Scale increases, the angle of pit sidewalls looks more vertical, since the tangent of the apparent angle is the tangent of the actual angle multiplied by the Z Scale.
- The overburden module must be placed before any scaling modules (such as explode and scale) to ensure an accurate slope angle during computations and subsequent visualizations.
- The grid resolution and resulting cell aspect ratios are very important. You cannot see any pit wall slope differences if those differences create a slope which is less than one cell wide from the bottom of the pit to the top. Therefore, very high resolutions in X-Y are needed for large sites with shallow pits. Expect long run times for overburden.
- Angles are defined from the vertical and are specified in degrees. A vertical wall pit is created with an angle of zero (0.0) degrees. A 2:1 pitch slope from horizontal would be an angle whose arctangent = 2.0, which is 63.4 degrees from horizontal, so you would enter 26.6 degrees (from vertical).
Ports
| Direction | Name | Type | Description |
|---|---|---|---|
| Input | Input Field | Field | The field to use for subsetting. |
| Output | Output Field | Field | The subset field. |
| Output | Wall Slope | Number | Wall Slope is the angle measured from vertical whereby 0 is vertical and 90 is horizontal. |
| Output | Buffer Size | Number | Buffer Size is the accuracy level resulting in the amount of excavation outside the subsetting level of interest. |
Properties
| Property | Type | Description |
|---|---|---|
| Allow Run | Boolean | Determines whether the module is allowed to execute. Set to True to allow this module to run. |
| Execute | Button | The Execute button forces the module to run even when Allow Run has been turned off. |
| Wall Slope | Double | Wall Slope sets the angle measured from vertical whereby 0 is vertical and 90 is horizontal. |
| Create Plume Buffer | Boolean | The Create Plume Buffer toggle determines if the overburden computations are rigorous and determines the buffer on all sides of the plume (ore body). If this is off, the module runs much quicker. |
| Buffer Size | Double | The Buffer Size sets the accuracy level resulting in the amount of excavation outside the subsetting level of interest. For example, a value of 10.0 would result in 10 feet of over-excavation from the subsetting level of interest. |
| Nodal Data | Choice | The Nodal Data control lets the user set the analyte of interest. |