Analyzing volume changes and comparing surfaces is essential for understanding site progress, managing earthworks, and ensuring conformance to design. Propeller’s Surface Comparison tool allows you to calculate cut/fill values, track progress, and directly compare survey and design data in the platform. This guide outlines how to perform comparisons using drone surveys, design files, and other surface data.
Use Cases for Surface Comparisons
Stockpile Measurement: Measure material volumes using a previous survey, design surface, or interpolated base.
Earthworks Progress: Monitor changes between surveys or from survey to design over time.
Design Conformance: Verify how closely the site matches your finished grade or design specs.
Landfill & Bench Volume: Measure vertical volumes in complex terrains.
Material Takeoff & Cut/Fill Maps: Generate detailed planning, logistics, and billing reports.
Volume Measurement Types
Area Progress: Compares a current surface (survey or design) to another design or survey.
Bench Volume: Measures vertical face volumes, useful for benches or blasts.
Cut/Fill: Calculates material change between two surfaces.
Stockpile: Measures volume using custom, smart, or reference-level base options.
Polygon: Custom measurement inside a manually drawn or magic-selected polygon.
Surface Area: Calculates the 3D surface area within a polygon.
Custom: Fully customizable to suit project-specific needs.
How to Create a Surface Comparison
From the toolbar, select Polygon as the measurement type.
From the measurement toolbar, select Polygon. Choose a template from the dropdown menu.
Use the Magic Polygon tool or manually draw a polygon around the area you want to measure.
Select the surfaces you want to compare in the From and To Surface dropdown menus.
You can easily switch between the From and To surfaces to reverse the comparison. This affects the Cut/Fill and Net values.
Select preferred units for distance, area, volume, and density. Easily toggle between metric and imperial units.
Comparing Design to Design
The Design-to-Design tool allows you to compare two design surfaces without uploading them as a survey.
Choose Polygon, then Area Progress from the toolbar.
Draw or use the Magic Polygon tool to outline your area.
In the From Surface and To Surface dropdowns, select two overlapping designs.
View calculated volume changes between the two surfaces.
Add/Edit Items in Measurement Templates
Customize measurements further by clicking +ADD/EDIT ITEMS and choosing from:
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Description
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Dropdown List
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Horizontal Area
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Vertex Elevation
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Surface Area
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Remaining to Design
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Material Properties
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Surface Comparisons
Templates can be saved for repeated use by clicking Create New Template. These templates will appear in the Polygon tool dropdown.
Using Shrink and Swell Factors
Shrink/swell describes how soil or material changes in volume when excavated (cut) or compacted (fill). Accurately calculating shrink and swell factors is critical for cost estimation, logistics, and planning in earthwork projects.
Shrink refers to the reduced volume of soil or material after it is excavated, transported, and compacted in a fill area.
Swell refers to the increase in volume of material when it is excavated from its original, natural state.
Enter the shrink-swell factor for the cut and fill to calculate the Cut, Fill, Net, and Total volumes. For example, if your swell factor is 5%, input 1.05. If your shrink factor is 5%, enter 0.95.
Using Deadband in Measurements
Users can set a deadband for their measurements using the volume comparison tool. This deadband will ignore surface changes less than the minimum value set for the heatmap and will not contribute any of those changes to the CUT/FILL/NET/Total values generated for that measurement.
To enable the deadband for your volume comparison measurement, scroll down below the CUT/FILL/NET/Total numbers to the Heatmap section of the measurement, and check the box for Use deadband in the calculation. Then, you must apply that change by clicking APPLY at the bottom of the measurement.
You will see an information box alerting you that the deadband has been applied successfully.
As a default for drone survey comparisons, the minimum value is 0.1ft (3 cm) in Imperial units, and 0.1m (10 cm) in Metric units. However, the Deadband is not enabled automatically.
Using DirtMate data in volume comparison measurements
The deadband of 0.1ft (3 cm) or 0.1m (10 cm) is automatically applied on measurement creation when DirtMate layers are toggled on. If the deadband is not applied, you will see a message with a link to APPLY DEFAULT. Please contact our Site Support team for questions about the deadband when applied to DirtMate measurements.
Best Practices and Tips
- Ensure that the surfaces overlap within the polygon for valid volume results.
- Use the heatmap visualization to clearly identify cut (blue) and fill (red) regions.
- For accurate shrink/swell values, consult geotechnical reports or onsite measurements.
- Save and reuse templates for consistent reporting across projects.
I still can't do it!
We wrote these articles to equip you with everything you need to get the job done on your own, but we understand that sometimes this isn't sufficient.
If you're stuck, you can connect with our support team by clicking the support button on the top right corner of your user portal.
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