Modelling underground voids

To model underground voids, use one of the methods below, depending on the following criteria:

  • Closed solid spherical - best for single scans.
  • Complex 3D Surface (point set triangulation) - best for multiple scans.
  • Advanced - best for multiple scans with many blind spots, or stopes with complex shapes.

Closed solid spherical

Model a single scan of a void as follows:

  1. Load the scan in a view window, and ensure it is selected.

  2. Filter by minimum separation to a minimum distance of 0.1 m. See Minimum Separation.

  3. Create a spherical surface. See Surface > Spherical Surface.

    1. Choose the (Select points) type then press Ctrl+A to select all visible data.

    2. Right-click a Spherical origin point field and select Point selection centroid.

    3. Set Spherical type to Closed Solid.

    4. Change selection type back to (Select objects) and click OK.

Complex 3D Surface

Model complex 3D surfaces with multiple scans as follows:

  1. Load the scans in a view window and ensure they are selected.

  2. Filter by minimum separation to a minimum distance of 0.3 m. See Minimum Separation.

  3. Create a complex 3D surface. See Surface > Complex 3D Surface.

    1. Set the feature size to 1.5 m minimum.

    2. Select or clear Smoothed surface as appropriate.

  4. Close any holes in the surface with Edit > Fix > Join and Close. Set the largest fragment as a separate object quantity to 1.

  5. Remove spikes from the surface with Edit > Fix >  Despike.

Advanced

Follow this procedure to model voids with many blind spots from multiple scans.

  1. Load the scans in a view window and ensure they are selected.

  2. Filter by minimum separation to a minimum distance of 0.1 m. See Minimum Separation.

  3. Crop to scan points from the area of interest.

  4. Create a series of loops around the stope with Underground > Loop Surface > Fit Loops with settings as follow (see Loop Surface > Fit Loops):

    • Set Points per loop to 150.

    • Set Loop spacing appropriately for the size of the stope.

    • Clear Filter obstacles.

    Create the loops in sections bounded by general changes in shape of the stope. The last loop should be close to and approximately parallel with the roof of the stope.

  5. Inspect the loops and remove any erroneous points.

  6. Create a surface from the loops with Underground > Loop Surface > Loop Surface. Set Loop ordering to Straight.

  7. Close the bottom of the stope by creating spherical surfaces, as with underground drive modelling (see Modelling underground drives > Close ends), except for the following:

    1. Set the Spherical origin point to the centre of the bottom loop.

    2. Set the Look point to a point on the stope floor.

    3. Adjust the height (Z value) of the Spherical origin point above the bottom loop.

  8. Repeat for the stope roof, adjusting for the change in direction.

    Note:  You might need to repeat this process several times to achieve the optimal results. Inspect the surface after each iteration.

  9. Identify the valid spherical surfaces and delete any junk surfaces that have been created.

  10. Select the three surfaces, then merge them with Edit > Fix > Join and Close.

  11. When the Close Objects panel appears, clear the Keep remainder fragments checkbox and click Close.

  12. Clean up the merged surface:

    1. Remove spikes with Edit > Fix >  Despike.

    2. Delete any bad facets.

    3. Repeat Join and Close.