How to Handle CMS data in Surpac

By

When using Cavity Monitoring System (CMS) data in GEOVIA Surpac™, it often needs some conditioning before it can be used to calculate volumes and for other downstream processes. This is due to a number of factors including extremely large number of points in a CMS survey; highly variable spatial point density (high density close to the scanner vs low density far from the scanner); internal spikes caused by rock intrusion, rock bolts, mesh, dust etc.

The quality of the data collected and the downstream use of the data will determine how you need to condition the data to achieve your objectives. Some common uses for CMS surveys include:

  • Volume of the CMS survey
  • Union it with other CMS surveys conducted at different points in time
  • Outersect or intersect with geology and engineering solids for reconciliation purposes

Prior to the availability of Surpac’s Mesh Tools module, the handling of CMS data was a laborious process and typically involved slicing the data into sections and then editing the strings on each section to remove the noise in the raw CMS data. By using a combination of Mesh tools and the Solids repair tool you can simplify the conditioning of the CMS survey in preparation for use in downstream processes, eliminate the need to slice, edit and retriangulate them and do all this much faster and with much less effort.

For example, consider the following CMS pickup:

 

These images show a raw CMS survey of an underground cavity. These surveys are characterized by numerous issues including spikes, both internal – which can’t be seen here – and external and highly variable spatial point density.

Traditionally, it is difficult to create a valid water-tight solid from which a volume can be obtained and which isn’t flawed by the existence of spikes caused by underground mining support systems. A further complication caused by the presence of many long skinny triangles is lack of geometric robustness when performing intersections with other solids. .

To overcome these challenges, follow the method of SIMPLIFY – EXPAND – REPAIR – CONTRACT. This method works for two reasons:

  1. The object does not need to be valid. It will become valid through the process, which provides significant time savings.
  2. It produces a result, which allows all other functions in Surpac to run quickly and easily. From volumes to unions, outersections and intersections, all these functions should produce error free results, quickly.

Here are the steps for the SIMPLIFY – EXPAND – REPAIR – CONTRACT process:

  1. Mesh Tools SIMPLIFY analyzes the triangles in the CMS survey and reduces the number of triangles while maintaining the solid’s geometric integrity. The degree of simplification is controlled by a tolerance value. Smaller tolerance values remove fewer triangles and force tighter compliance with the original geometry while larger values remove more triangles with looser compliance to the original geometry. The object below has been simplified, but still has many long skinny triangles and generally bad geometry in the object.
  2. Mesh Tools EXPAND will create a new solid where the triangles are geometrically robust and are far better for unions, outersections or intersections with other CMS surveys or drive solids.
  3. REPAIR the object so that when it is contracted, the shape will be valid and almost identical to the original objects shape. Solids repair will automatically fix this object. It is also extremely quick due to the geometrically robust geometry resulting from the EXPAND step.
  4. CONTRACT the object back to its original dimensions after it is valid from Solids repair – There is no need to simplify any further. The final conditioned CMS survey is shown below:
  5. OPTIONAL – DEVIATION ANALYSIS saves the object and runs a deviation analysis on it with the original object. When running deviation analysis, make the simplified solid the base object. Deviation analysis is also a great way to check the deviation from design and actual not only of stopes, but also of development drives.

Once those steps are complete, volumes, outersections, intersections or unions can all be successfully performed. Because of the uniform and conditioned nature of the object, all of these functions work quickly, reducing the time for downstream processing. As an added bonus, the file size of conditioned objects is much smaller which makes working with and displaying multiple drives and stopes very quick.

By following these steps, you can effectively and efficiently handle CMS data in Surpac.

Here are a few bonus tips:

Tip 1: Save the object as binary, and the file size will be approximately 50% smaller again.
Tip 2: When editing the final shapes or cutting out drives from the pickup , use the data select tools
Tip 3: A free macro within the module can complete this entire process for you, and produce a Valid Object in approximately 10 seconds depending on data size.

Looking for more Surpac Tips & Tricks? Check out How to Export Surpac Models into 3DVIA Composer. Be sure to check back for more Product Tips & Tricks.

 

 

 

 

 

0
Ash Colton

Ash Colton

Mining Knowledge Consultant, GEOVIA at Dassault Systèmes
Ash Colton is a qualified Mining and Engineering Surveyor with over 14 years' experience. Ash has worked on a number of mine sites (open cut and underground) and specializes in GEOVIA Surpac, MineSched and Macros. Ash is based in Perth, Australia.
Ash Colton

Latest posts by Ash Colton (see all)