Contours are now generated directly from your elevation layers instead of being locked in at processing time. Open any DSM or DTM in your map, choose an interval, and Birdi builds a contour layer for you — as many times as you like.
This means you can:
Generate contours at whatever interval suits the job, not a fixed interval chosen weeks ago
Create multiple contour sets from the same DEM and compare them side by side
Style and label your contours the same way you would any other vector layer
Regenerate at a tighter or coarser interval whenever your needs change
Contour generation is available on all plans.
Note: Contours are no longer an option on the processing request form. If you've processed a map recently and can't find the contour tick-box, that's why — you now create them from the DEM itself, at any time, at no extra cost.
When to use contours
You need to understand the shape of the terrain before designing or excavating
You're preparing a site plan, drainage assessment, or civil design and need linework at a specific interval
You want to communicate slope and elevation change to people who don't read a colour ramp easily
You need to spot ridges, batters, benches, or low points across a site
You're exporting terrain data into CAD or GIS and need contour line strings rather than a raster surface
Step-by-step: creating contours
1. Check you have a DSM or DTM
Contours are generated from an elevation layer, so you'll need one on your map first.
Open your map and look in the Layers panel
Confirm you have a DSM (surface, including vegetation and structures) or a DTM (bare earth) available
If you don't have one, request processing for your map and include a DSM or DTM in your outputs
Tip: Use a DTM for design and drainage work where you want bare ground. Use a DSM when you need the surface as-flown, including stockpiles, vegetation, and built structures.
2. Open the layer menu
In the Layers panel, find your DSM or DTM
Right-click the layer, or select the … menu next to the layer name
3. Select Create contours
Choose Create contours from the menu
The contour settings panel opens
4. Choose your contour interval
Select an interval from the dropdown. The interval is the vertical distance between each contour line — a smaller interval gives you more lines and more detail.
Available intervals:
0.25 m (≈ 0.8 ft)
0.5 m (≈ 1.6 ft)
0.75 m (≈ 2.5 ft)
1 m (≈ 3.3 ft)
1.5 m (≈ 4.9 ft)
2 m (≈ 6.6 ft)
3 m (≈ 9.8 ft)
4 m (≈ 13.1 ft)
5 m (≈ 16.4 ft)
10 m (≈ 32.8 ft)
Intervals display according to your unit setting. To switch between metric and imperial, go to Settings in the top-right corner and toggle Metric / Imperial.
Tip: Tight intervals over a large or steep site produce a lot of linework, which takes longer to generate and can make the map hard to read. Start at 1 m for a general site overview, then go finer over the specific area you care about.
5. Wait for your contours to generate
Birdi processes the DEM and builds the contour layer
Larger areas and smaller intervals take longer
When it's finished, the new contour layer appears in your Layers panel
You can keep working on your map while contours generate.
6. Review your contours in Table view
Each contour is a line string with its elevation stored as an attribute, so you can check the values before you style anything.
Select your contour layer in the Layers panel to open the Layer toolbox
Click the Table icon to open Table view
Confirm the elevation field is present and the values look right for your site
7. Style your contours
Contours behave like any other vector layer, so all the usual styling options apply.
Style by type — one style for every contour in the layer:
Open the Style tab in the Layer toolbox
Adjust line colour, line weight, opacity, and line style (solid, dashed, or dotted)
Click Apply
Style by field — colour your contours by their elevation:
In Style > Style by field, choose the elevation field
Pick a colour preset (continuous or stepped), or customise your own
Add, remove, or edit bands/classes to set your breakpoints
Click Apply to update the layer and the legend
Tip: 5–7 classes usually balance detail and readability. Keep contour lines a little darker than your orthomosaic so they stay legible over imagery.
8. Add labels to your contours
Labels put the elevation value directly on the line, so anyone reading the map can pick out heights without hovering.
In the Layer toolbox, open the Labels option
Select the elevation field as your label
Adjust the label appearance to suit your map
Click Apply
Tip: On a dense contour set. Generate contours at 5 m with labels turned on, and a second set at 0.5 m without labels, then display both together — you get fine detail and readable heights.
9. Export your contours
Contours download as a zipped Shapefile, ready to drop into your CAD or GIS package.
In the Layers panel, right-click your contour layer
Select Download
The layer downloads as a ZIP file
What's in the ZIP:
File | What it holds |
| The contour line strings themselves |
| The index that lets software find each line quickly |
| The attribute table, including your elevation values |
| The coordinate system, so your contours land in the right place |
Keep all four files together. They only work as a set — if you unzip and move the .shp on its own, most software won't open it, or will open it with no elevation values and no positioning.
Compatible with: any software that reads Esri Shapefiles, including QGIS, ArcGIS Pro, AutoCAD Civil 3D and Map 3D, Global Mapper, Trimble Business Center, 12d Model, and Carlson. Most machine-control and survey packages will also import Shapefiles directly.
Tip: If your CAD package needs DXF or DWG instead, import the Shapefile into QGIS or Civil 3D first and export from there — that way the elevation attributes carry across.
Best practice tips
Match the interval to the decision you're making. Drainage and earthworks usually need 0.25–0.5 m; a general site overview reads better at 1–5 m.
Use a DTM for design work. A DSM will drape contours over vegetation and buildings, which isn't what you want for ground modelling.
Generate more than one set. Contours are free to create and quick to delete, so try two or three intervals and keep the one that reads best.
Rename each layer clearly — for example Contours – DTM – 0.5 m. It saves confusion when you have several sets on the same map.
Check accuracy expectations first. Contour accuracy depends on the accuracy of the underlying DEM, including your ground control setup.
Hide the contour layer before exporting imagery if you want a clean orthophoto without linework.