When you’re working with geospatial data, accuracy starts with location. And that location? It all comes down to something called a Coordinate Reference System (CRS).
Let’s break it down.
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A Coordinate Reference System (CRS) defines how coordinates in your map relate to real locations on Earth. It includes details like the map projection, the Earth model (datum), and how height is measured (ellipsoidal vs geoidal).
Every map has a frame of reference. A CRS tells software like Birdi how to interpret coordinates — whether they're in degrees of latitude and longitude, or in metres north and east of a known origin point.
There are two main types of CRS:
That’s important because Earth isn’t flat — and mapping a 3D curved surface onto a 2D screen always involves some form of distortion. The CRS helps control that distortion based on your region and use case.
A CRS isn’t just a projection — it’s made up of a few components:
You’ll often see CRS written like: GDA2020 / MGA Zone 56 + AHD – Translation: “Use the GDA2020 Earth model, flatten it with the MGA Zone 56 projection, and reference elevation to mean sea level (AHD).”
In short: the CRS is what ensures your outputs — whether it’s a drone-captured orthomosaic or a set of terrain contours — land in the right place, with the right elevation, every time.
Every time you process an orthomosaic, DEM, or contour map, you're not just generating visuals — you're creating geospatially referenced data. That means every pixel, point, or line in your file has a coordinate tied to the Earth.
The CRS determines:
If you’ve ever seen an orthomosaic floating 50 metres off where it should be — or a DEM that doesn’t line up with your survey data — chances are there’s a CRS mismatch somewhere in the pipeline. Getting it right means your outputs land exactly where they belong.
You might’ve noticed something new in your processing options recently — we now support multi-CRS processing directly from the new map interface.
That means more flexibility and control over how your outputs are aligned, especially if you're working across multiple regions or systems.
For UTM-based outputs, we’re running the most recent EGM2008 geoid model to support accurate height referencing — great news if you're dealing with elevation-critical projects.
It depends on your use case:
And of course, whatever CRS you pick during processing is the one your outputs will be in — so tools like QGIS, ArcGIS, or AutoCAD will know exactly how to position your data.