Propeller is used for high-accuracy drone mapping by survey teams all over the world, which has made us experts in a very particular area: coordinate reference systems.
If you’re planning work or tracking progress on a worksite, you’ll have designs, plans, and survey data, all of which will be in your site’s coordinate reference system (CRS). It might be a national grid or state plane system, or it might be in locally calibrated coordinates.
How can you get drone data, which is collected in the global GPS coordinate reference system (WGS84), to align with the CRS you use on your site?
Making drone data useful is all about collecting the right information and communicating it effectively. You need to be producing data that meshes seamlessly with the information you already have. The answer is usually lies in using the right coordinate system.
What coordinate reference systems does Propeller support?
Every piece of georeferenced survey data, whether a topographical terrain model or an orthomosaic, will have some kind of coordinates associated with it which describe its place in the real world.
To ensure you and anyone who intends to use the data are speaking the same language, it’s important to make sure you’re working in the same system. Desktop GIS packages like QGIS and Global Mapper support a variety of common coordinate reference systems which are recognized by international authorities like the European Petroleum Survey Group (EPSG) and companies like ESRI, the makers of ArcGIS.
Propeller has support for all of these systems. If you provide us with the name of a public CRS you use, we’ll sort out the rest for you.
To ensure the highest accuracy, many sites operate on a “locally calibrated” CRS, where known points and monuments on the site are surveyed to establish a CRS that’s very precise on that particular site. Propeller also supports these locally calibrated coordinate systems.
For example, if you have a site calibrated by a Trimble rover, you can use Trimble Business Center to export your calibration in a JXL, upload it directly to Propeller, and we’ll handle the rest for you. Alternatively, you can reach out to us at email@example.com along with any information about your site’s calibration and we’ll work with you to get it ready for processing.
We also support the ability to customize existing systems to suit your needs or to define your own. We have had customers use local systems from council archives and modified existing nationally recognised systems to produce models that mesh seamlessly with existing historical data.
If you have a projection definition that doesn’t have an EPSG code or want an existing system in a different linear unit, you can contact our data specialists directly through the Propeller Platform. We’ll get everything set up so you can process your data without delay.
How your coordinate reference system works in Propeller
Once you know the coordinate system you want to work in, it’s easy to use it throughout the Propeller Platform.
In your file downloads: our default survey file downloads include DXF files and point clouds in your site’s default CRS. You can configure your default CRS for a site when you set it up. You can see below the downloads for a site in EPSG:2232, which is the NAD83 / Colorado Central (ftUS) state plane CRS for sites near our US headquarters in Denver.
In Propeller’s online viewer: you can change the coordinate reference system (or projection) and output units (metric or US imperial) from the Settings menu. This can be useful if you want to observe a particular location on your site where you know the latitude and longitude, or if you’ve got data you want to cross-reference in another CRS.
Simply click the Edit icon next to projection in the settings menu and enter the corresponding ID for the system you are after in the EPSG text field.
AeroPoints: Using AeroPoints for easy, automated ground control? You can also use any of these coordinate systems—or a local calibration that you’ve configured—to process your ground control points in your own CRS.
And you can still configure another CRS to download your results.
Regardless of the coordinate system you want to work in, Propeller will ensure you and your team are speaking the same language at every stage of the project.