Terrain
SiteCAD gives you precise control over elevation data — from global context terrain down to sub-meter grading edits. Learn how terrain layers work, how to shape the ground with brush tools, and how to visualize and export your earthwork.
Terrain Layers
Ground data is organised as a stack of terrain layers, managed from the Terrain button in the status bar. Each layer carries up to three sources — elevations, imagery, and a 3D model — and the three resolve independently down the stack. Exactly one layer is active at a time, and that is where your brush edits are stored.
Your grading
The layer you are editing. It typically starts with no sources of its own, so everything below shows through until you paint. The first brush stroke on a piece of ground copies that ground down from whatever is resolving there and starts editing the copy — so a grading alternative costs nothing until you actually grade something.
Your existing conditions
A layer whose sources are your own survey data — a high-resolution bare-earth elevation model from drone photogrammetry or LiDAR, an orthomosaic for imagery, and optionally a photogrammetry mesh as its 3D model. Within your site it replaces the global default with much higher detail.
Cesium World Terrain
The bottom of every stack, with satellite imagery alongside it. Always available, no setup required. Resolution varies by location but is typically 30 m or coarser — useful for context but not detailed enough for engineering.
Elevations, imagery, and the 3D model each fall through on their own. Elevations come from the highest layer that has edited ground at that spot, or from the highest layer with an elevation source; imagery comes from the highest layer with an imagery source; the model from the highest layer with a model. So your grading can sit on your survey's elevations while your orthomosaic still draws underneath it. Hiding a layer takes it out of the stack without deleting anything it owns.
Where Terrain Comes From
There is no separate step to prepare terrain before editing it. Every site already has ground under it, and the brush works on that ground directly. Bringing in your own survey data is a separate — and optional — piece of setup.
Editing Copies as It Goes
The first time the brush touches a piece of ground, SiteCAD reads the elevations that currently resolve there, stores them on the active layer, and edits that copy from then on. Ground you never touch stores nothing at all, which is why sites of several square kilometres stay manageable. You never see or place the underlying storage — there is no object to create, no grid to line up with, and no seam where edited ground meets untouched ground.
Every stored point also remembers how far it has moved from the elevation it started at. That difference is what the cut/fill overlay draws, and it is why changing a layer's elevation source later keeps your grading instead of discarding it.
Managing the Stack
Click Terrain in the status bar to open the terrain panel. Each row is one layer; clicking a row makes it the active one. The controls on a row are:
- Show / hide — take a layer out of the stack without deleting what it owns
- Import terrain override… and Import imagery override… — bake a local GeoTIFF onto that layer
- Edit layer — rename it, set its terrain, imagery, and 3D model sources (an existing geostore asset, or Upload new… to upload a file for that source), and set its cut/fill options
- Delete layer — remove the layer and everything it owns
Add Layer at the bottom stacks a new empty layer on top — the usual way to start a grading alternative without disturbing what is underneath. Duplicate, inside Edit Layer, copies a layer's sources into a fresh layer above it and leaves the edits behind.
The AI assistant and operations scripts can drive the same stack — adding layers, switching which one is active, showing and hiding them, and pointing a layer at a different source — using the terrain functions listed under Operations.
Brush Tools
The terrain brush is your primary tool for shaping the ground. Pick it up from the Terrain Brush button in the toolbar, press B, or pick it from the viewport's right-click menu; the toolbar swaps to the brush controls and your cursor becomes a circle on the ground. It works like a painting brush — click and drag to modify elevations in real time. Four modes cover all common grading operations.
Raise
Pushes terrain upward under the brush. Use for building pads, berms, levees, and fill areas.
Lower
Pushes terrain downward. Use for ponds, drainage channels, excavation, and cut areas.
Smooth
Averages nearby elevations to reduce sharp edges. Use after rough grading to blend transitions.
Flatten
Levels terrain to a target elevation. Use for building pads, parking areas, or any flat surface.
Brush Settings
Radius
0.3 – 10 mControls the size of the brush circle. Smaller for detail work, larger for broad grading.
Strength
0 – 1How aggressively the brush modifies elevation per stroke. Start low for fine control.
Falloff
Smooth, Linear, Gaussian, ConstantHow the brush effect tapers from center to edge. Smooth and Gaussian produce natural transitions; Constant applies full effect across the entire radius.
Start with a large radius and low strength for rough grading, then switch to a smaller radius for detail. Use Flatten to establish target elevations for pads and platforms, then Smooth to blend edges into the surrounding terrain. Each brush stroke is a single undo step.
Visualization
SiteCAD provides two terrain visualization layers that help you understand the ground surface and the impact of your grading work.
Topographic Contours
Contour lines are traced from the ground surface as it currently resolves — your edits included — using marching squares, and displayed as an imagery overlay. You can configure:
- Major and minor intervals — e.g., 5 m majors with 1 m minors
- Index contours — thicker lines at larger intervals for readability
- Colors and opacity — customize line colors and layer transparency
Contours update live as you brush, giving you immediate feedback on grades and drainage direction.
Cut/Fill Overlay
The cut/fill overlay compares each terrain layer against the original background terrain to classify it as cut or fill:
- Cut areas (below original) — dark soil tones on the default Dirt ramp, blue on the color ramps
- Fill areas (above original) — light earth tones on Dirt, red-brown on the color ramps
- Ramp mode — Dirt texture, Linear color, or Stepped contour, each coloring cut/fill differently; set in the Terrain panel
A per-layer threshold (default 0.05 m, set in Edit Layer) prevents noise in areas with negligible change. The same dialog has a per-layer Cut/fill enabled checkbox — a layer with it off is skipped even when the overlay is on. Contours and the cut/fill overlay are independent layers, so both can be visible at once.
Import & Export
Bring elevation and imagery in from survey and GIS tools, and take your design back out.
Bringing Terrain In
GeoTIFF elevation (.tif, .tiff)
A DTM raster from a drone survey, LiDAR processing, or a GIS export. Read in the browser and baked straight onto the active layer as edited ground — no upload, no round trip.
GeoTIFF orthophoto (.tif, .tiff)
Aerial imagery, baked onto the active layer the same way and draped over whatever elevations resolve underneath it.
Uploaded terrain and imagery assets
Larger surveys and orthomosaics are uploaded once, stored in your site’s asset catalog, and set as a layer’s source. They stream in rather than being baked, so they stay cheap at site scale.
Photogrammetry mesh
A textured 3D model is a layer’s third source. It renders above the ground surface and can be clipped where you have placed replacement geometry.
A GeoTIFF has to carry a coordinate-reference tag and the band layout SiteCAD expects — elevation in the first band, or RGB/RGBA for imagery. WGS84, NAD83 and the WGS84 UTM zones are reprojected automatically; a file in a State Plane or national grid is refused with a message naming the code, so re-export it in a UTM zone or WGS84. The import runs in the background and reports on the status bar, so you can keep working, and it counts as a single undo step. An import that fails stays flagged on the status bar's Terrain chip until you open the Terrain panel and dismiss it, so you cannot miss it while you work elsewhere.
Taking Terrain Out
A terrain layer exports as a LandXML surface. The export button on a layer's row in the layer panel writes the ground that layer holds itself — every tile an import baked or the brush sculpted — as one triangulated (TIN) surface, in latitude, longitude and metres above the ellipsoid, that Civil 3D and similar tools read and that SiteCAD imports back as an equal layer. A layer that only shows its base terrain source owns no tiles and has nothing of its own to export, so its button is disabled. Progress shows on the status bar and the export can be cancelled there. Cut/fill data and GeoTIFF elevation grids do not come out this way, and there is no terrain mesh export.
What the whole stack travels in is a scenario bundle or snapshot, which carries every layer and every edited tile — the right way to hand a design to a colleague, archive it, or move it between machines. For contractor deliverables, pair the graded layer's LandXML surface with a boundary-and-trace export (GeoJSON, DXF, LandXML) and the design intent.