Quantity monitoring in mining environments is a challenge that can be simplified by using multiple drone surveys of the same area over time. By combining drone surveys, mine managers can obtain additional insight regarding how much dirt was moved within the desired timeframe. This does allow better decision-making regarding future work for the mine; however, the drone data has to be efficiently analyzed to be useful for monitoring the mine. 


This article demonstrates how to use drone surveys along with Virtual Surveyor, over a mining site, to track progress over time and quickly generate quantity reports and Cut/Fill maps.



Overview


Create and Organize Your Terrain States 

To deal with multiple drone surveys over time you need to use the Terrain State functionality. 

  1. Create a Terrain State for each date the drone is flown over the mine.  
  2. Each drone survey data package—which includes the DSM and orthomosaic—should be imported into the corresponding Terrain State. 
  3. Switch from one terrain state to another using the drop-down menu.



Clean the Terrain

Drone data coming from mining operations commonly have many machines (bulldozers, excavators, dump trucks, etc.). You should not include these machines in your volume calculations. To clean the terrain, you can use the Remove Object tool or the Replace Terrain tool.  



To help you detect objects that need to be removed, you can also use the Slope Steepness Terrain Lens. This must be done for each terrain state of your drone survey package.


Select the Operation Area

Mines typically cover a large area of land and drone surveys often cover the entire mine.  For your survey, you want to focus on weekly or monthly operations in localized or specific areas. You need to determine the area where you want to calculate your quantity changes. For example, you may focus on blasting areas or excavation zones. Use the Boundary drawing tool to trace the limits of the area you want to focus on. 



This boundary is required for Cut/Fill analysis. If you want to generate an analysis over the whole mine, create a boundary to work in over the entire area.


You can also use multiple boundaries to break up and work on different parts of the mine. See our article Combine Techniques to Survey Large Areas for ideas to help the efficiency of your workflow.


Create a Cut/Fill Maps

Use the Terrain State manager to switch to the previous drone survey. 

  1. Select the Boundary and go to the TOOLS tab. 
  2. In the Volumes group set the Reference Type to Terrain State and select the most recent drone survey as reference for the Cut/Fill calculation within the Reference State box. 
  3. Click on the Cut/Fill button to launch the calculation. 
  4. Cut areas appear in warm colors (yellow to red) and fill areas appear in cool colors (cyan to blue). 
  5. Cut/Fill values for the entire area are available in the Volume box. 



If you have multiple areas of interest, you can select all the boundaries (by holding Ctrl on your keyboard). Cut/Fill calculations are run in parallel, but each area has a dedicated map and quantity result.


Create a Cut/Fill Analysis

Now that the Cut/Fill map is available, let's make it better and easier to analyze. 

  1. Select your Cut/Fill map within the Viewport or through the Project View to get access to TOOLS tab for Cut/Fill. 
  2. Set the Min. Cut/Fill value to highlight only significant operation areas. 
    1. Using a 0.3ft (10cm) value typically clears noisy areas. 
  3. Now reduce the stretch value a little to enhance the color appearance.



It is possible to focus the analysis on one cut or fill area to get quantity results for that specific area. 

  1. Select the Cut/Fill map to get access to the TOOL tab and activate the Extract Cut/Fill area tool. 
  2. Click on the desired area. 
  3. A new Cut/Fill item is created and if selected, related quantities display in the Selection box.


Export Results

If you need to deliver a quantity report, you can export the Cut/Fill analysis results and use these—in third-party software—to present a detailed report. Volume info can be exported as .csv to fill a spreadsheet or as .shp to draw a map. 

  1. Activate all the Cut/Fill items you want to export within the Project View and go to the EXPORT tab. 
  2. In the Cut/Fill group select the export format and click on Export Cut/Fill.


The Selection box also contains a copy icon to copy the information directly to the clipboard.


 

Here is a sample report laid out with Microsoft Excel using volume information from the clipboard and a Viewport screenshot. 

It is also possible to export what you see in the boundary as a localized image. 

  1. Activate all the items you want to export within the Project View, select a Boundary, and go to the EXPORT tab. 
  2. In the Terrain group, select the export format and click on Export Image.