Winter 2013 Newsletter • November 2013 •

Geomatics Highlight!

Answering the big question, "How Much?" with Volumetric Surveying

We start this newsletter with an old paradigm you heard from your mother or grandmother. "Too much of a good thing is bad for you." Apparently, over indulgence will create a glutinous or covetous person in you.

Now...a mountain of valuable minerals would qualify as a "good thing"! Given that "too much" is a relative term, (the limits to which one must defer to some acceptable social norm by some unit of measure) but by which unit and by which measure do we use? It seems that our mothers never considered measuring a mountain of valuable minerals, gravel, or the size of an open void when giving young minds sage wisdom. It may be disrespectful to argue with mother in pointing out that her judgments are subjective, unless of course, we are measuring a mountain of gumdrops!

Measuring items by unit seems simple and arcane enough that an army of clerks with their green shades can go all day with their adding machines. Then how do you accurately measure the volume of a pile or maybe...a "mountain of something"? There is no army of green shades able to count the grains of sand or grains of rice; therefore, you must measure by weight or volume. This creates our first paradox. Weighing a mountain of gravel would be impractical and costly since you would need to extract the gravel and move it across a scale with trucks. And so, the most practical and cost effective method of measure is volumetric.

This leads us to our second paradox of measurement methodology and accuracy. How do we determine the best method to cost effectively measure volumes and to what degree of accuracy?

Estimation by geometry and conventional survey equipment is commonly used. However, this method has a large degree of error and is sometimes fraught with danger to the surveyor. These methods are crude and force us to accept volumetric measuring as an estimation. With the expanded use of Robotic Total Stations, RTK-GPS, High Definition Scanning (HDS), or LiDAR technologies, we can now provide accurate volumetric surveys for a host of applications in a cost effective and safe manner.

Types of volumetric surveys

volumetric_dataWith the increase in technology, our ability to provide volumetric information in new ways has increased dramatically. We are no longer hindered by the limits of the frail human body, which would otherwise be unattainable. We can now; safely gather data in areas such as deep voids, chemical or nuclear hazardous zones and confined spaces requiring permits. New applications are being considered and applied regularly -- lowering the cost of data recovery. The physical boundaries and the high cost of data acquisition are being shattered with the advent of these new technologies. White Shield Geomatic professionals are continuously applying the technologies in creative and inventive ways.

Volumetric data can be obtained for determining material volumes by using Aerial LiDAR from a fixed wing plane or low flight helicopter. We can also obtain the same data at ground level by utilizing Terrestrial LiDAR using 3D Laser Scanning. Instead of relying on traditional survey equipment or weight dependent truckload counts to estimate the volume of stockpiles, we now use methods that are faster and more accurate. Volumetric calculations are simplified for large piles of material such as mine tailings, gravel piles, warehouse grains and even fertilizer.

Additionally, LiDAR information of open pit sites provides more accurate volumes for payment and as-built requirements as required for reclamation, excavation of open-pit mines, landfill volume determinations or construction backfilling.

landfill_volumesTypically, we would use 3D laser scans to survey the exterior of a pile or pit; however, it is also a great way to obtain the volume or shape of the inside of a void. For mining applications or tunnel boring, point cloud data from an underground 3D laser scan is used to determine the amount of material removed and the shape of the dropped volume. The analysis is used in the planning software. End-users can then ensure the intended direction of the blast was met and further development continues in the correct direction.

Another unique application is the computation of volumes of non-liquid materials within a tank. HDS scanning technology is an ideal tool for these uneven surfaces. While the total capacity of a tank or storage container may be known, the volume of contents in the container is difficult to determine accurately. This is especially true in the case of irregular contents of hazardous materials, which cannot be directly measured physically. Using HDS, the volume of the void above the tank contents can be measured by employing some simple math to calculate the total contents of the tank. Also, keep in mind that not all piles of granular material are composed of solids. It may be worthwhile to determine accurately only the granular material by subtracting out voids, by taking representative samples and applying the percent voids to the overall scan.

Types of Deliverables

Point cloud data can be handled directly by most design software. Applications such as Autodesk, MicroStation, MineSite and other design packages now have included a point cloud engine that allows the existing conditions point data to be imported directly. For Building Information Modeling (BIM) applications or planning purposes, existing conditions information can be a key element in the design process workflow.

Our mothers would be proud to know that we can accurately, quickly and safely collect volumetric data. However, please do not tell them that our next project is measuring product inventory at the candy factory with our Leica HDS C10 laser scanner!

If you have any interest seeing a demonstration of our 3D scanning and modeling services, please call or write us here at White Shield.

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