Most quarry survey specifications require a survey of breaklines. Virtual Surveyor allows you to create a lightweight line survey from your drone data that you can export to a common CAD format and upload it into mining and quarrying CAD software. In this article, we'll show you an efficient method for drawing breaklines and some options you have to enhance your line survey.


Overview


Step 1: Import Your Drone Survey Data

Create your project and drag and drop your drone survey dataset (Orthophoto + DSM) into the Project View.

Ortho and DSM of a mine. New project.


Step 2: Create a Line Survey as Breaklines

Use the polyline tool to capture the tops and toes of the slopes as breaklines. Use left-click along the top of the slope and right-click when you are done drawing.

Manually drawing a breakline at the top of a slope.


Use the Guided Breakline Tool to Draw Faster: Among the many features of Virtual Surveyor, the Guided Breakline tool combines the speed of computer calculation with the human mind that can better interpret the terrain .


Key Concept: The Guided Breakline consecutively creates a line of points at similar distances between one another that conforms to the top or bottom of a slope in the direction you point it. Your first click helps the tool determine the elevation you are starting from, and the second click determines the distance between points in the direction you want to draw additional points along the breakline of the slope.



With the Polyline tool active, click on the Guided Breakline drawing mode and go to the bottom of the slope and give it a couple of clicks in the direction you want it to go. The breakline systematically draws along lowest part of the slope. 

Using the Guided Breakline tool to draw a breakline at the toe of a slope.


Enable the Slope Steepness lens to help you manually draw the breaklines: You can get a different visual to help you draw with the Guided Breakline by activating the Slope Steepness lens found in the Analysis tab. You can always use this lens to make it easier for finding the tops and toes of the slopes when drawing them with the Polyline tool, as it visualizes the terrain in a color palette, with a dark blue line that helps identify the breaks (top or bottom) of the slope.

 

Key Concept: The Slope Steepness lens wraps color over the terrain to indicate the steepness of a slope. The steeper the slope the more intense the color becomes. You can use two different types of color pallets: one will show areas of rapid elevation change, and the other will show slopes over a defined percentage (threshold) that you set.



Using the Guided Breakline tool to draw a breakline at the toe and top of a slope with the Slope Steepness lens enabled.


Note: You can use the keyboard shortcut Alt+S to quickly enable/disable the Slope Steepness lens.


Correcting the Guided Breakline: For areas that are a bit tricky to draw, if you're using the Guided Breakline tool and your line goes off course it's easy to fix. Just press the Backspace button on your keyboard to delete points that went off course, then give it a new break to follow. You can always switch back to the Free drawing mode and manually place the breaklines if the slope isn't defined enough for the computer to recognize. Using the Guided Breakline to draw a breakline at the top of a slope with the Slope Steepness lens enabled and quickly correcting the line it when it goes off course.


Edit your breakline vertices: Once you're done drawing the tops and toes, you may find vertices that aren't optimally placed on the breaks of the slopes. You can edit any of the vertices on the polylines you drew by right clicking a drawn polyline from the Viewport or Project View and selecting Edit Vertex from the quick access menu . You can now easily add, delete, or move points to get the most precise representation of the slopes. If you turn the Slope Steepness lens on and off for reference, it is often easier to see the highs and lows of the slope and where best to place your vertices.

Drawing breaklines with the Guided Breakline tool and editing the vertices using the Edit Vertex tool.


When you've finished creating all the breaklines for your site, it should look something like the image below:

Overview of a Quarry with all the tops and toes drawn for the project site area.


At this point in the project, you can skip forward and export your breaklines to create CAD file (.dxf, .xml, or .shp file), but you do have the option of generating a surface to assess and check your breaklines for quality. We'll also show how you can go one step further in Step 3 of this article to make a more more detailed representation of the surface by adding points around your breaklines. 


Optional: Generate a Surface for the Quarry from the Breaklines

You can take an additional step here and quickly generate a lightweight surface model from your quarry drone data to check your line survey and validate the quality of your model before you deliver it as an exported item.


Key Concept: the TIN (Triangulated Irregular Network) is a vector-based representation of a land surface. It models the surface in three dimensions using a network of connected triangles and is commonly used for projects that require an precise representation of the terrain.



To generate the surface: 

  1. Ensure all your line items are visible and click on Triangulate All to generate the surface.
  2. Use Edit Surface to remove unnecessary triangle edges.

Generate and edit the TIN of a mine.

Finished TIN from the breaklines of a mine.


Key Concept: The Triangulate All/Within tool creates a TIN surface from your drawn/inserted points and breaklines. 



You can preview the TIN by itself in the Viewport by turning off the Elevation and Image Terrain items from the Project View.

Preview the TIN without the Orthophoto and DSM.


Step 3: Add Points for a More Detailed Surface

You can quickly add points to your breaklines for a more complete representation of the surface. 


Create a boundary: The best way to create a boundary in this situation is to extract the boundary from the created surface (TIN). To extract the boundary:

  1. Select the surface generated from the breaklines (as shown in the optional step above).
  2. Go to the TOOLS tab.
  3. Click on Extract Boundary.


Note: You can use Edit Vertex and Densify tools to fine tune the vertices on your boundary.



Use Hull Selection to draw a boundary around your breaklines to add a point grid. You can also edit the vertices on the boundary.


Create a Point Grid: You can create a point grid to get more regularity in the surface. Setting the grid to 10 meters is a good choice as it keeps the surface light-weight. We strongly advise against going smaller than 10 meters. To create a point grid:

  1. On the Home tab, set the point grid Type to Triangular/Rectangular
  2. Set the Grid Size to 10.00 m
  3. Click Point Grid to create your points within the drawn boundary. 

Create a Triangular point grid within a boundary.


Edit the points: Edit points using the Point and Erase tools to remove or add points as necessary. Since you just added points from a grid, you should only need to use the Erase tool to remove points that were placed on surface objects.

Remove points from machinery and buildings using the Erase tool.


Optional: Create a TIN of the Points and Breaklines

To assess your work and ensure a good surface creation, ensure both your Point Grid and all your Breakline project items are enabled. Then select the boundary and click on Triangulate Within (in the HOME tab). Create a TIN from the points and breaklines.


You now have a more detailed surface when including a 10-meter spacing point grid than the original one you created when only using breaklines, and it can still be used as a light-weight CAD model.

Finished TIN from the breaklines and points of a mine.


You can also further enhance the detail of your surface using a special tool exclusive to Virtual Surveyor called Auto-Flip Edges. There is no change to the amount of data used, the appropriate triangle edges are flipped to align with the breaks on the slopes.


Step 4: Export Your Line Survey

To use your survey in mining or quarrying software, export it as a .dxf, .xml, or .shp file. The Export feature works as "what you see is what you get" or "WYSIWYG", so you'll only enable what you want to export.

  1. Ensure the boundary is disabled if you just want points and lines in your export.
  2. Go to the EXPORT tab and select your desired format.
  3. Click Export Survey and save the file with the desired name and location.

Export your lines and points to a .dxf file.


Optional: Upload Your Line (and Points) Survey to CAD

Export lines and points as a .dxf and open it in a CAD program.

Image showing the mine's breaklines and points .dxf loaded into CAD software.


Optional: Upload Your TIN to CAD

You can also export the TIN as a .dxf and open it in CAD program. Just make sure the TIN is enabled and visible in Virtual Surveyor when you click Export Survey. Then load the .dxf file into CAD. 

Exported quarry TIN viewed in a CAD software.


All the options we've shown you are just to expand your tool belt and help you decide the best way to create a surface model. You can try using these digital surveying concepts on your own dataset and very quickly create lightweight surface models with precise and accurate details.


Use Q-Points Instead of Breaklines

Another option for creating a quarry survey is by using Virtual Surveyor's Q-Points tool. Using Q-points gives you an accurate topo surface, except it is a much faster method.


Key Concept: the Q-Points tool is an intelligent tool that uses an algorithm to model your topography with precisely placed points along the breaks of slopes within a boundary area you create. This tool is useful for bare-earth terrain. 



You can read more about how to do this in our Create a Surface for a Quarry article.

Generate Q-points over a mine with an elasticity of 1.00 meter.


Tips & Tricks

Display the topography as different kinds of surfaces: You can display your surface as either a Triangulated Irregular Network (TIN) for a 3D model or as contour lines in 2D mode to help you assess your survey.

Show your surface as a TIN, contours, or both.


Organize your survey items: You can use the Layer Manager to give a structure to your project. 

  • Create and manage layers in the Project View
  • Rename and renumberProject Items or move them from one layer to another. 
    • For example, you can create layers to group crest, top of bank, bottom of bank, etc:

Organizing project items into layers


Use the styling options in the HOME tab to set the shape, size, and color of your survey items.