This article gives you step by step instructions on how to design a coastal rock wall in the Virtual Surveyor app. We use this example project to present and illustrate the steps that are common in a standard design workflow. You can create a functional design and generate the grading, estimate the amount of material necessary to build the design, export the surface as a machine control model, then track progress over time. 

Overview

• Create a Design from Your Baseline
• Draw the Design Line
• Designing the Structure
• Grading
• Improving the Design
• Material Estimation
• Exporting a Machine Model
• Progress Monitoring
• As Built
• Credit

Create a Design from Your Baseline

When creating a design in Virtual Surveyor, it is essential to work with two timesteps: one for the baseline survey and one for the design. The baseline timestep contains the elevation model (DSM) and orthophoto from your initial survey, which serves as the foundation for your design.

Follow these steps to set up your design in Virtual Surveyor:

1. Transfer Your Drone Data: Move your processed drone data from the Terrain Creator app to the Virtual Surveyor app using the Open in Virtual Surveyor button.
2. Open the Timeline: Access the Timeline by clicking the calendar icon and selecting the drone data date in the status bar (or navigate to the View tab and click on Timeline).
3. Create a Design Timestep:
   1. Use the Timeline functionality to create a new timestep and name it Design.
   2. Copy the DSM and orthophoto from your baseline survey's drone data and paste them into the Design Timestep. This ensures your design is built on the accurate elevation model and imagery of the baseline survey.
      

By organizing your project into distinct timesteps, you can maintain a clear separation between the original survey data and your design work, allowing for precise and efficient design development.

Draw the Design Line

In the Design Timestep, use the Polyline tool to draw the first part of your design. In this case, the rock wall needs to be the same level of the road, so we'll start by drawing the design line along the white painted line at the edge of the road.

1. Switch to 2D view mode to make drawing along the edge line easier.
2. Click on the Polyline tool and enable the Distance Drawing Guide.
3. Set the Distance Drawing Guide to 4 meters. 
4. Start drawing a line along the path you want to create your design. 
   1. This example project uses 4-meter increments for the design line in order to capture the topography and create a regularity in the surface once it is generated.
      
   2. Continue drawing a design line following the Distance guide of 4 meters.
      
   3. Obscured ground points. Sometimes, when drawing a design line, you might come across obstacles in your path that make it difficult to follow a path. In this example, the edge line is obscured by a truck. Rather than trying to guess where the line might be placed under the truck, you can enable the Angle Drawing Guide to help ensure you maintain a path along the edge line. For this example, we can keep the line at 0 degrees from its original heading and continue drawing the line vertices at 4-meters apart.
      
5. Finish drawing the line to where the design ends (you can change the line color to make it easier to see for the design).
   
6. Switch to 3D mode to inspect your drawn line. You can see that part of it ended up on top of the truck. Quickly fix that by moving these vertices to the ground level.
   1. Right-click on the line and select Edit Vertex in the mini toolbar.
   2. Switch the mode to Interpolate Z (Linear) and select two endpoint vertices to interpolate the Z height of all vertices positioned between the selected endpoints. This will ensure any moved vertices all follow the slope of the terrain that the line may be on.
      

Designing the Structure

Now you can create the top of the rock wall using the design line.

1. Right-click on the design line and select Offset Line from the mini toolbar.
2. We'll set the offset line Distance to 7.66 meters (For this example project, we have already calculated the necessary measurements).
3. Enable the ΔZ mode in the Offset Z Method and set the elevation to 0 meters to keep the derived line at the same elevation as the design line.
4. Left click at the 7.66-meter drawing guide to derive a new line that is parallel to the design line.
   
5. Select both lines to create a surface.
   1. Hold Shift then click-and-drag your cursor over both lines to select them.
6. Go to the Home tab and click Triangulate Selection to create a surface that can be used for creating a grading.
   

Grading

With the top of the design created as a surface, you can now create a grading for the design.

1. Highlight the surface and go to the Tools tab. 
2. Set the Fill Slope to -30 degrees for the outer part of your coastal protection wall.
3. Click the Grade tool and Virtual Surveyor will calculate a graded surface with the appropriate fill slope and automatically modify the terrain to fill within the surface.
   

Get a clearer look at the design. You can get a clearer look at the design by disabling the orthophoto. To create the design line, you needed the orthophoto, but now that you've created the design, the photo no longer matches the conceptual reality, so you can get a better understanding of what the design looks like with the orthophoto disabled.

Improving the Design

You can see that the graded portion of the design overlaps the entryway to the beach. The rock wall structure needs thorough coastal protection, but we still need an entryway in order to access the beach from the main road. So, we can improve how the rock wall is designed around the entryway. We remove the overlapping triangles and model the entryway with breaklines

Edit the surface:

1. Right-click on the surface and select Edit Surface from the mini toolbar, then select Remove Edge.
2. Remove the edges of the surface that overlap onto the entryway.
   1. Multiple edges can be removed at the same time when you hold Shift and click-and-drag to select multiple lines at once.
      

Model the access road by adding additional breaklines. Turn the orthophoto back on as we'll need a visual reference of the current location of the access road:

1. Disable the modified terrain in the Project View so that it doesn't interfere with any newly drawn design lines.
2. Switch to 2D mode to make it easier to draw new design lines.
3. Click on the polyline tool and start drawing the outer portion of the design while still using the 4-meter guide.
4. Once you get close to the entrance, enable the Angle guide and set it to 90 degrees to draw a line towards the entrance.
   
5. Switch to the Arc tool and draw two arc lines to round out the coastal wall for the entryway.
   1. The first line drawn from the entrance to the top portion of the surface.
   2. The second line drawn from the entrance line to the bottom portion of the graded surface at the end of the entryway.
      

Recreate your design surface. Finalize the rock wall design line in 3D mode and recreate your surface design to include the entryway.

1. Switch to 3D mode and use Edit Vertex to edit the top arced line and use Interpolate Z (Linear) to level the road entrance vertex to the top vertex of the surface design.
2. Highlight the two arced lines along with the surface by holding Shift + left-click-and-drag to highlight all three.
3. Click Triangulate Selection from the Home tab to combine the newly drawn breaklines to the existing surface for a final surface design.
   
4. Disable the Orthophoto using the shortcut on the Home tab.
5. Select the Surface and go to the Tools tab.
6. Click Modify Terrain and turn off the Orthophoto to see your updated design.
   

Material Estimation

Now that the design is created in line with the specifications, we can use it to estimate how much rock (material) we'll need to build the structure. You can use the Cut/Fill tool to estimate the material. But first, hide all lines so that only the design surface is shown.

1. Select the design surface.
2. Use the Extract Boundary tool to create a boundary around the modified terrain.
3. Select the new boundary (created around the terrain).
   1. This boundary is used to compare 2 timesteps: the Design and the Baseline survey flown on July 1st.
4. Ensure you're in the Tools tab and change the Volumes dropdown option to Use a Timestep.
5. Select the appropriate Reference State from the Timeline options (In this case, you want to compare the Design Timestep with the baseline).
6. Click the Cut/Fill tool to generate your material estimation.
   

Select your Cut/Fill and look at the Selection tab for your design's Volume information.

Get the information you need. You can see from the Fill that you will need 1 557.84 m³ of rocks to build the rock wall.

Exporting a Machine Model

You can export a machine model so that the designed rock wall structure can be read and built on-site via a machine.

1. Ensure the completed design surface is enabled and showing in the Viewport.
   1. Also ensure that no other design lines are showing.
2. Go to the Export tab and set the file Format to .xml.
3. Click Export Survey and name the file. 
4. Click OK to export the design to a chosen file location.
   

Progress Monitoring

Once the structure is being built on site, you will want to create and add the next drone dataset as another timestep to compare and track progress made on the original design. 

Use Terrain Creator to create a new timestep: 

1. After finishing the photogrammetry process of the latest flown drone photos in the Terrain Creator app, click the To Existing button. 
2. The dataset is moved to the Virtual Surveyor app as a newly created Timestep that is automatically created in the Timeline with the drone flight date as the name.

Compare drone datasets over time. Use the Profile tool to compare the design over time.

1. Click on the Analysis tab.
2. Click on the Profile button.
3. Draw your profile line over a portion of the coastal wall that is currently being built.

You can now use the Profile lines to compare the original drone dataset to the design and the being-built datasets.

1. Click on Add Timestep in the Profile View.
   
2. Select the Timestep you wish to compare profile lines with from each dataset on your Timeline.
   

As Built

When the construction is finished, you fly one last drone survey to create your As-Built survey. 

Credit

Special thanks to Mark Steggall for his valuable contributions in shaping this article.