- Explain why a terrain tool physically cannot sculpt an overhang, in one sentence.
- Use proportional editing to make large landforms in seconds rather than minutes.
- Sculpt with the three brushes that do most of the work, and know what each is for.
- Judge a landform from eye height, which is the only view that matters.
Brief · 15 min Two kinds of ground
Nearly every terrain question resolves to one distinction, and it is not a matter of taste. It is a matter of what the data structure can physically represent.
| Heightfield | Mesh | |
|---|---|---|
| What it is | A grid pushed up and down — a bedsheet over furniture | Actual geometry, vertices anywhere in space |
| Good at | Big open terrain, painted material layers, cheap detail falloff | Overhangs, caves, arches, hero rock |
| Cannot do | Anything that folds back over itself | Scale cheaply to kilometers |
A heightfield stores one height per point on the ground. That is the whole definition, and everything follows from it. A cave mouth needs two heights at the same spot — floor and roof — so a heightfield cannot hold one. Neither can an overhanging cliff, or an arch, or anything you could walk underneath.
So when a terrain tool refuses to sculpt the overhang you want, it is not a missing feature and there is no setting to find. You are asking the structure for something it has no way to store. That shape has to be a mesh, which is Day 3.
Build · 45 min Sculpt a landform
- Plane, then subdivide
Add a plane, enter Edit mode, right-click → Subdivide, and repeat. Your subdivision count is a hard ceiling on detail — you cannot sculpt a feature smaller than the spacing between vertices. Decide the resolution before you start sculpting, not after you get frustrated.
Edit mode, everything selected, right-click. Subdivide is the first item. 
The Adjust Last Operation panel appears bottom-left after Subdivide. Click it, set Number of Cuts; repeat Subdivide as needed. - Big shapes first, with proportional editing
Press O to turn it on. Now moving one vertex drags its neighbors in a soft falloff, and the scroll wheel sizes that falloff. One vertex pulled upward with a wide falloff is a believable valley in about ten seconds.
Do all of your large landforms this way before you go anywhere near a brush. It is far faster than sculpting, and large shapes are what the viewer actually reads.
One vertex pulled up with proportional editing on (the ring-shaped icon in the header is lit). The falloff dragged the neighbors into a smooth hill. - Sculpt mode for everything after that
Three brushes do most of the work. Draw raises ground. Clay Strips gives chunky, faceted rock. Smooth calms down anything that got noisy.
Hold Shift to smooth with whatever brush is active, Ctrl to invert it, and F to resize. Those three modifiers are worth more than learning ten more brushes.
Sculpt mode. 1 The toolbar holds the brushes — Draw, Clay Strips, Smooth are the three you need. 2 Radius and Strength in the header, or F and Shift+F. 3 The asset shelf along the bottom is the same brushes as thumbnails. The blue ring is the brush. - Add irregularity you did not author
A Displace modifier with a Clouds texture breaks up the tell-tale smoothness of hand sculpting. Keep the strength low — noise is seasoning, not the meal. Terrain that is noisy everywhere reads as static rather than as landscape.
The sculpted landform with a Displace modifier at strength 0.6 and a Clouds texture: fine irregularity you did not hand-author. 
The Displace modifier in the Modifiers tab. Click the texture field to make a new texture, then set its type to Clouds on the Texture tab (the checkerboard icon at the bottom of the tab column). Keep Strength low. - Look at it from the ground
This is the step everyone skips, and it decides whether the terrain is any good. Drop the camera to about 1.7 m and look across the landform rather than down at it.
Terrain that reads beautifully from above routinely reads as nothing at all from where a person actually stands — and a player is always standing.
The same terrain seen through a camera placed 1.7 m above the ground. Add a camera, put it at eye height, and look through it with Numpad 0. This is the view that decides whether the terrain is any good.
You are going to decimate, add scale cues and judge the silhouette tomorrow. A landform that is roughly right and still cheap to change is exactly what Day 3 wants. Detail added now is detail you may throw away.
- You can say why an overhang is impossible in a heightfield without hedging.
- You built your large forms with proportional editing, not with a brush.
- You know what Draw, Clay Strips and Smooth each do, from using them.
- You looked at it from eye height, and it still reads as terrain.