Beginner ~8 min read

Understanding Terrain

Understand how SiteCAD stacks elevation data, visualize it with contours, and make your first terrain edits with brush tools. Terrain is the foundation of every site design — this tutorial shows you how it works.

1

How Terrain Layers Work

SiteCAD stacks ground data in layers. When the editor needs an elevation at any point, it works from the top of the stack downward and uses the first layer that has something to say there.

Your edits

The active layer

The one layer you are currently editing. Brush strokes are stored here, and they win over everything below. It starts empty — a fresh layer shows whatever is underneath until you paint on it.

Your survey

A layer with your own data

High-resolution elevation from drone photogrammetry or LiDAR, plus an orthomosaic for imagery, set as that layer's sources. This is your existing-conditions baseline.

Global default

Cesium World Terrain

Worldwide terrain and satellite imagery underneath everything. Always available, no setup needed. ~30 m resolution — good for context, not for engineering.

What this means in practice

You never have to prepare terrain before editing it. The first brush stroke on a piece of ground copies the elevations resolving there onto the active layer and edits the copy — ground you never touch stores nothing. Because each edited point remembers the elevation it started at, the original surface is always available underneath for cut/fill comparison.

2

Set Up Your Stack

You can start brushing straight away on the worldwide terrain. This step is about getting your own data underneath your edits, and giving yourself a layer to grade on.

  1. Make sure you have a site with a site area defined (see Your First Site) and its anchor point set — the brush refuses to paint until there is an anchor to measure against.
  2. Click Terrain in the status bar to open the terrain panel. You will see the layers your site already has; clicking a row makes that layer the active one.
  3. To bring in your own survey: use Edit layer (the pencil) to point a layer's Terrain and Imagery sources at assets you have uploaded, or use Import terrain override… to bake a local GeoTIFF straight onto the layer.
  4. Click Add Layer to stack an empty layer on top, and make it active. Grading there keeps your proposed design separate from your existing conditions — you can hide it to see the site as it stands today.
Nothing to capture

There is no step that turns terrain into an editable object. Editing is what creates the copy: the first stroke on a piece of ground stores just that ground on the active layer. Layers can also be added, switched, hidden, and re-sourced from the AI assistant or an operations script.

3

Turn On Contours

Contour lines are the quickest way to understand your terrain's shape. SiteCAD traces them from the ground surface as it currently resolves — your edits included — and displays them as an overlay on the 3D view.

  1. Find the Topo chip in the status bar and click its On/Off state to switch contours on. The first time, SiteCAD samples elevations across your site area and traces the lines — you'll see a brief spinner.
  2. Contour lines appear immediately — minor contours at 1 m intervals, major contours at 5 m intervals, and bold index contours every 25 m.
  3. Contours update live as you edit terrain. Zoom in to see fine detail; zoom out for the big picture.
Reading contours

Closely spaced lines mean steep terrain. Widely spaced lines mean flat ground. Concentric closed loops indicate hilltops or depressions. Water flows perpendicular to contour lines, from high elevation toward low.

4

Shape Terrain with Brushes

The terrain brush lets you sculpt the ground like a painting tool. Click and drag across the ground to raise, lower, smooth, or flatten it.

  1. Enter brush mode: click the Terrain Brush button in the toolbar, press B, or right-click in the scene and pick it from the context menu. You do not need to select anything first — the brush works on whatever ground is under the cursor, and writes to the active terrain layer.
  2. The toolbar changes to show brush controls: mode selector, radius slider, strength slider, and falloff curve.
  3. Pick a brush mode:

Raise

Push terrain upward. Use for berms, building pads, or fill areas.

Lower

Push terrain downward. Use for ponds, swales, or excavation.

Smooth

Average neighboring elevations. Use to blend rough transitions.

Flatten

Level terrain to a target elevation. Use for pads and platforms.

  1. Adjust radius (0.3–10 m) and strength (10%–100%). Start with low strength for fine control.
  2. Click and drag on the ground to sculpt. Each brush stroke is a single undo step — press Ctrl+Z to undo.
  3. Press Esc or click Done to exit brush mode.
Workflow tip

Start with a large radius and low strength for rough grading. Then switch to a smaller radius for detail work. Use Flatten to set target elevations for pads, then Smooth to blend edges into the surrounding terrain.

5

Practice Exercise

Try this short exercise to reinforce what you've learned.

Build a Simple Building Pad

  1. Open the Terrain panel and add a layer to grade on, so your edits stay separate.
  2. Turn on contours to see the current ground shape.
  3. Enter brush mode and select Flatten.
  4. Set a moderate radius (~3 m) and full strength.
  5. Click on a spot to establish your target elevation, then drag to level a rectangular area.
  6. Switch to Smooth and blend the edges where the pad meets natural terrain.
  7. Watch how the contour lines update to show a flat plateau with graded transitions.

Next Steps