Terrain Surface Editing — Sculpt, Extrude, Volume Points
Shape mounds, flat terraces, retaining steps, and drainage grades directly on the terrain surface.
Terrain Surface Editing — Sculpt, Volume Points, GradingThe terrain surface editing tools are available from the Edit tab in the terrain workspace HUD. The three tools suit different scales and types of terrain work:
- Sculpt Brush — the most freeform tool; paint directly on the surface with configurable radius, strength, and action (raise, lower, smooth, flatten). Best for large organic shaping — mounds, bowls, gradual transitions.
- Volume Points — drag cone-shaped control handles that pull or push the surface with an RBF (radial basis function) smooth falloff. Best for precise, localised elevation adjustments with a controlled influence area.
- Extrude Tool — selects a flat region of terrain and applies a height profile with a cross-section shape chosen from eight presets. Best for embankments, terraced steps, ridges, and defined edges.
All three tools support full undo/redo — each stroke, drag, or extrude is a separate undo step.
Sculpt Brush — painting the terrain surface
Click Sculpt in the Edit tab to activate the sculpt brush. The cursor shows a circular brush indicator on the terrain surface as you move.
Brush settings (shown in the HUD while sculpt is active):
- Radius — the size of the brush circle (drag the radius slider or scroll the mouse wheel while hovering)
- Strength — how strongly each stroke affects the surface (higher = larger elevation change per stroke)
- Shape — Circle, Square, or Diamond brush shape
- Falloff — Soft (smooth edge), Medium, or Hard (sharp edge)
- Action — what the brush does:
- Raise (left-click) — lifts the surface up within the brush circle - Lower (left-click) — pushes the surface down - Smooth — averages the elevation within the brush circle, reducing sharp transitions - Flatten — sets all points within the brush to the elevation at the brush center
Paint by clicking or clicking and dragging across the surface. For Raise and Lower, hold the mouse button down and move to create a continuous stroke. Release to end the stroke — each stroke is one undo step.
Use a large, soft brush with low strength for broad landscape shaping — this builds up gradual changes over multiple strokes. Switch to a smaller hard brush for sharper transitions and more defined edges.
Volume Points — precise local elevation control
Click Volume Points in the Edit tab to switch to volume point editing mode. Volume points are cone-shaped handles placed on the terrain surface — dragging them up or down adjusts the elevation of the terrain within their influence radius.
Adding volume points: 1. Click anywhere on the terrain surface to place a new volume point cone 2. A cone appears with a circular influence radius indicator 3. Drag the cone up to raise the terrain, or drag it down to lower it
Adjusting influence: Select a volume point (click its cone) and use the inspector controls:
- Influence Radius — how far from the cone the effect extends (in meters)
- Falloff Strength — how steeply the effect reduces from the center to the edge (1.0 = linear, lower values = faster drop-off)
Multiple volume points: Place several volume points across the terrain and adjust them individually. The terrain interpolates a smooth surface through all the control points using radial basis function interpolation — changes to one cone affect nearby cones with a natural smooth transition.
To delete a volume point, select it and press Delete.
Volume points are excellent for creating gentle swales and ridges — place a point on either side of the intended drainage path and raise the ridges while leaving the swale center point at a lower elevation.
Extrude Tool — defined edges and terraces
Click Extrude in the Edit tab to activate the extrude tool. The extrude tool selects a flat rectangular region of terrain and applies a configurable height profile to one or both edges.
Creating an extrusion: 1. Drag a rectangle on the terrain surface to define the extruded region 2. The region highlights on the terrain 3. In the Extrude panel, choose a Top Surface Preset — one of eight options that define the cross-section shape: - Flat — horizontal top surface (simple terrace) - Slope In — slopes downward away from the near edge - Slope Out — slopes downward away from the far edge - Peaked — ridge-shaped, rising to a peak in the middle - Valley — bowl-shaped, dipping to a lowest point in the middle - Step In — steps up from the near edge with a vertical riser - Step Out — steps up from the far edge with a vertical riser - Custom Profile — define your own cross-section using the X/Y profile curve editor 4. Set the Height — the maximum elevation change of the extruded form 5. Click Apply to commit the extrusion to the terrain
Custom Profile: Select the Custom Profile preset to open a 2D curve editor. Draw the cross-section profile as a bezier curve — the X axis represents position across the terrain region, the Y axis represents height. The curve is mapped onto the selected region.
The Flat preset with a vertical height creates a simple horizontal terrace. Combine two adjacent extrusions — a Flat terrace with a Slope Out between levels — to create a terraced garden with graded transitions.
Create flat terraces with Pad and Sloped Pad
Click Pad in the Grading Primitives group to draw a flat area held at a specific elevation. Click to place footprint vertices and press Enter to commit the shape — the terrain levels to the pad elevation inside the footprint and blends smoothly to the surrounding ground at its edge. Use Sloped Pad instead when you need a tilted plane, such as a driveway ramp or a sloped patio. Each pad is named automatically (Pad 1, Pad 2, and so on) and appears in the terrain modifier list.
A Pad is much faster than sculpting a flat area by hand — it enforces a mathematically level surface inside the footprint regardless of what the imported terrain looked like before.
Add hard edges, walls, and drainage lines
Use Retaining Wall to draw a vertical step along a centerline path — the terrain drops sharply on one side to create a wall condition. Use Breakline to force the surface elevation precisely along a drawn path, such as a swale or a path edge. Grade Limits draws a containment boundary that prevents your edits from spreading outside a defined zone. Drainage grades the terrain to flow outward from a drawn line. Each tool draws on the surface and commits the shape with Enter, or cancels with Esc.
Draw a Grade Limits boundary around the area you're actively working on before using Spray Sculpt — it acts as a containment fence and prevents edits from accidentally spilling into neighboring areas that must stay at their existing elevation.
Place spot elevations and slope callouts
Use the Height tool in the Model flyout to place a labeled spot elevation marker at a specific point on the surface — the marker reads the current terrain height at that location. Use the Slope tool in the Analyze flyout to place a slope percentage and angle annotation at a point. Both annotations update if the terrain under them is subsequently edited, so the readouts reflect the current surface.
Place spot elevation markers at key design points — finished floor level, top of wall, bottom of ramp, and drainage outlet — before presenting to a client. They make grading intent immediately legible.
Review your work with analysis overlays
Open the Analyze flyout on the left toolbar to turn on the Slope or Cut/Fill overlay. The Slope overlay color-codes every surface cell by gradient steepness — useful for spotting accessibility issues or unstable grades. The Cut/Fill overlay compares the current shaped terrain against the original base terrain and shows where material has been removed (cut) or added (fill), with a summary panel showing total volumes.
The recommended shaping order is: Volume Points for the overall landform, Spray Sculpt for organic transitions and fine detail, then Grading Primitives (Pad, Sloped Pad, Retaining Wall, Breakline) for defined built forms and hard edges. Working in this order avoids re-sculpting areas that a later Pad or Retaining Wall will override.
Deleting a terrain modifier (Pad, Breakline, etc.) from the modifier list immediately removes its effect from the surface and cannot be undone with the standard undo shortcut once the workspace is closed. Delete modifiers only when you are certain they are no longer needed.
Keyboard Shortcuts
| Key | Action |
|---|---|
| Drag | Apply Spray Sculpt brush along cursor path |
| Click | Place a Volume Points control point |
| Delete | Remove selected Volume Points control point |
| Enter | Commit drawn Pad, Retaining Wall, or Breakline |
| Esc | Cancel current draw or exit active tool |
| Ctrl+Z / Cmd+Z | Undo last editing operation |
Frequently Asked Questions
Can I edit imported terrain, or only terrain I created from scratch?
Both. Volume Points, Spray Sculpt, and all Grading Primitives work on any terrain surface — whether imported from survey data, generated from contour lines, or created from scratch. All edits are applied on top of the existing elevation data as a stack of modifiers, so the original import is never overwritten.
How do I smooth rough or noisy imported terrain?
Use Spray Sculpt with the Smooth action. Set a large radius and moderate strength, then drag repeatedly over the rough areas. Multiple smooth passes progressively reduce noise without introducing artificial flat spots. You can also smooth the terrain at import time using the smoothing option in the import wizard.
Can I undo a single Spray Sculpt brush stroke?
Yes. Each stroke is a separate undo step. Press Ctrl+Z (or Cmd+Z on Mac) to step back one stroke at a time until the surface is back at an earlier state.
What is the difference between a Pad and a Breakline?
A Pad levels the terrain inside a closed polygon footprint to a flat elevation and blends its edge to the surrounding ground. A Breakline forces the terrain to pass through a specific elevation along an open or closed polyline path — it does not create a flat interior, only a controlled ridge, valley, or edge condition. Use Pads for flat terraces and level areas; use Breaklines for swales, path edges, and retaining conditions that follow a line.
How do Grade Limits affect the other tools?
Grade Limits draws a containment boundary that constrains the effect of Spray Sculpt and Volume Points to the area inside the boundary. Editing outside a Grade Limits boundary has no effect on those areas. This is useful when you want to shape one zone of the site without accidentally disturbing areas that must stay at their existing elevation, such as a neighbor's property edge or a protected planting area.