Intermediate ~10 min read

Terrain Brush Basics

Use brush tools to raise, lower, smooth, and flatten terrain with precision. This tutorial covers entering brush mode, understanding each brush type, tuning radius and strength, and using falloff curves for natural-looking grading.

1

Prerequisites

There is very little to set up — the brush works on the ground your site already has.

  1. A site with its anchor point set (see Your First Site). The anchor is what ties screen positions to real coordinates; without it the brush refuses to paint and says so.
  2. A terrain layer to grade on. Open the Terrain panel from the status bar and click Add Layer so your edits stay separate from existing conditions — or just grade on the layer that is already active. See Understanding Terrain.
  3. Contours enabled (optional but recommended). Toggle them from the status bar's Topo button so you can see elevation changes in real time.
Nothing to prepare

Brush strokes are stored on the active terrain layer, at the top of SiteCAD's elevation stack. You do not have to capture or create anything first: the first stroke on a piece of ground copies the elevations resolving there onto the active layer and edits the copy, so you are always sculpting from a real surface.

2

Entering Brush Mode

Brush mode replaces the normal toolbar with terrain-specific controls. There are three ways to activate it.

  1. From the toolbar: Click the Terrain Brush button. Nothing needs to be selected first.
  2. From the keyboard: Press B. The same key exits brush mode again.
  3. From the viewport: Right-click in the scene and choose Terrain Brush from the context menu.

Once active, the main toolbar transforms into the brush toolbar and your cursor becomes a circular brush indicator on the terrain surface. Press Esc or click Done to exit brush mode at any time.

3

The Brush Toolbar

The toolbar gives you quick access to every brush setting. Here's a left-to-right walkthrough of each control.

Mode Buttons

Four brush modes — Raise, Lower, Smooth, Flatten — each with its own icon. Click to switch instantly.

Radius

Slider from 0.3 m to 10 m. Controls the circular area affected by each stroke. Start around 2–3 m for general grading.

Strength

Slider from 10% to 100%. Controls how much each stroke affects the terrain. Lower strength gives finer control.

Falloff

Dropdown with four curves — Smooth, Linear, Gaussian, Constant — that control how the brush effect tapers from center to edge.

Done

Exits brush mode and returns to normal selection. You can also press Esc.

Where your edits go

The brush toolbar has no target picker. Strokes are always written to the active terrain layer, which you choose by clicking its row in the Terrain panel. If you want a stroke to land somewhere else, switch the active layer there first.

4

Brush Modes

Each mode defines how the brush changes elevation under the cursor. Choosing the right mode for the job is the key to efficient terrain editing.

Raise

Pushes terrain upward under the brush. Each frame you hold the mouse adds elevation, so a slow drag produces a gentle rise and a fast click-hold builds a mound. Great for berms, building pads, and fill areas.

Lower

Pushes terrain downward — the inverse of Raise. Use it for ponds, drainage swales, excavation, and trenches. Combine with Smooth afterward for natural-looking edges.

Smooth

Averages neighboring elevations to blend rough transitions. Each vertex converges toward the mean of its 8 neighbors. Use after Raise/Lower to soften hard edges and create natural transitions.

Flatten

Levels terrain toward a target elevation. The target is sampled from the first point you click — then every vertex under the brush blends toward that height. Perfect for building pads, parking areas, and level platforms.

Which mode when?

Start with Flatten to establish level areas at known elevations. Use Raise/Lower for shaping slopes and drainage. Finish with Smooth to blend everything together. This flatten-shape-smooth workflow mirrors how real grading is done.

5

Radius & Strength

Radius and strength work together to control the scale and intensity of your edits.

Radius

0.3 m – 10 m (default: 1 m)

The radius defines the circular footprint of the brush on the terrain surface. A small radius (0.3–1 m) gives fine detail control — good for individual features. A large radius (5–10 m) covers broad areas for rough grading passes.

Strength

10% – 100% (default: 50%)

Strength scales the magnitude of each brush stroke. At 100%, the brush applies its full effect per frame. At 10%, each frame makes only a subtle change — useful for fine-tuning elevations without overshoot.

Rule of thumb

For your first pass on a new area, use a large radius with low strength (e.g., 5 m / 30%). This lets you rough-in the shape without creating sharp artifacts. Then reduce the radius and increase strength for detail work.

6

Falloff Curves

The falloff curve controls how the brush effect transitions from full strength at the center to zero at the edge. Different curves produce different visual results.

Smooth

Default

S-shaped curve (cosine interpolation). Full effect at center, gentle roll-off, zero at edge. Produces the most natural-looking results for general grading.

Linear

Straight-line taper from center to edge. Predictable and uniform — good for mechanical grading where you want consistent slope.

Gaussian

Bell-curve shape. Strong effect concentrated at center, rapid falloff further out. Great for sculpting focused features like drainage points.

Constant

Uniform effect across the entire brush radius — no taper at all. Creates hard edges. Useful for Flatten mode when you need a crisp pad boundary.

Practical tip

Leave falloff on Smooth for most work — it mimics natural terrain transitions. Switch to Constant when you specifically need a hard edge (like flattening a building pad), then use Smooth brush mode afterward to blend the transition.

7

Sculpting Techniques

These common workflows combine modes, radius, and falloff for real site engineering tasks.

Building Pad

  1. Switch to Flatten with Constant falloff.
  2. Set radius to cover the pad area (3–5 m) and strength to 100%.
  3. Click the target elevation, then drag across the pad footprint.
  4. Switch to Smooth with Smooth falloff to blend the edges where the pad meets natural ground.

Drainage Swale

  1. Use Lower with a small radius (1–2 m) and moderate strength (40–60%).
  2. Drag along the desired drainage path, following the natural low points.
  3. Make multiple passes for depth control — easier to add depth than remove it.
  4. Smooth the banks with a wider radius to create gentle side slopes.

Berm or Embankment

  1. Use Raise with Gaussian falloff for a peaked profile.
  2. Drag along the berm centerline with moderate radius and strength.
  3. Repeat passes to build height gradually.
  4. Finish with Smooth to round off sharp ridges.
Undo is your friend

Each brush stroke (click-and-drag) is a single undo step. Press Ctrl+Z to revert the last stroke if it didn't look right. Experiment freely — you can always undo.

8

Practice Exercise

Try this exercise to build muscle memory with all four brush modes.

Grade a House Site with Drainage

  1. Open the Terrain panel and add a layer to grade on, so your edits stay separate.
  2. Turn on contours so you can see your edits in real time.
  3. Enter brush mode and select Flatten with Constant falloff.
  4. Set radius to ~4 m and strength to 100%. Click a spot to set your target elevation, then flatten a rectangular area for a house pad.
  5. Switch to Smooth (Smooth falloff, radius ~3 m, strength 50%). Blend the pad edges into the surrounding terrain.
  6. Switch to Lower (radius ~1 m, strength 40%). Carve a shallow swale leading away from the pad for drainage.
  7. Use Raise (Gaussian falloff, radius ~2 m) to build a small berm on the uphill side of the pad.
  8. Final pass: Smooth everything to create natural transitions. Watch the contour lines update to confirm water will flow away from the pad.

Next Steps