Orientation and Layer Height for Terrain
Terrain is mostly gentle slopes, the worst case for layer lines: on a nearly flat slope each layer steps sideways a long way. Print base down for flatness and simplicity, use a thinner layer height or variable layer height so only the shallow regions slow down, and keep enough top layers that infill never shows.
Why terrain stair-steps so badly
A printer builds the model in flat slices. Where a surface slopes, each slice ends a little to the side of the one below it, leaving a step. On a steep face the steps are narrow and nearly invisible. On a gentle slope each layer has to step a long way sideways before the surface rises one layer height, and the result looks like contour lines. Most real terrain, even after exaggeration, is gentle slopes.
Slope angle is measured from the bed. Examples: 0.2 mm layers on a 5° slope give steps about 2.3 mm wide; on a 2° slope, about 5.7 mm. Halving the layer height to 0.1 mm halves the step width.
That formula gives you the three levers: thinner layers, steeper slopes (more vertical exaggeration, which changes the model), or a different orientation.
Orientation
Two choices, with a clear trade-off:
| Base down (flat on the bed) | On edge (standing up) | |
|---|---|---|
| Stair-steps | Worst on gentle slopes, as above | The gentle slopes become near-vertical faces, so steps are small |
| Supports | Usually none on FDM | Needed for the landscape and the overhanging base edge |
| Flatness | Flat bottom, ideal for tiles that butt together | Bottom is a wall; tiles may not match |
| Print time | Few layers for the height | Many more layers |
Base down is the usual choice, and the only sensible one for a set of tiles. The relief lesson compares the two orientations for carved panels in more detail (printing a relief STL), and print orientation covers the general rules.
Layer height on FDM
Layer height is limited by the nozzle. Prusa says layer height should be below 80% of the nozzle diameter and generally does not suggest going lower than 0.10 mm, since finer layers bring only minor quality gains Rule of thumb. Polymaker gives a reliable range of 25 to 75% of the nozzle diameter, for example 0.1 to 0.3 mm with a 0.4 mm nozzle Rule of thumb. Polymaker also notes that 0.1 mm layers take about three times as long as 0.3 mm with the same nozzle and speeds Rule of thumb.
For terrain, that time cost is why variable layer height is worth learning.
Variable layer height
Variable layer height lets the slicer use thin layers only where the surface needs them and thick layers elsewhere. Prusa documents three modes in PrusaSlicer:
- Adaptive: calculates a layer profile from the model, controlled by a Quality/Speed slider.
- Smooth: smooths the profile so layer height changes gradually.
- Manual: paint finer or coarser layers at chosen heights yourself.
Prusa says it can give significantly shorter print times with minimal loss of quality, and its automatic method ties layer height to the slope of the surface. Terrain is a good fit with one catch: variable layer height works by height, not by area. Each Z height gets one layer thickness across the whole tile. If a gentle valley and a steep cliff sit at the same height, both get the fine layers. Check the layer profile the slicer produces against your map, and compare the print-time estimate with a fixed-layer slice, to see whether it is worth it for this tile.
Other slicers have similar features, often called adaptive layer height; check your slicer's documentation. The general lesson is choosing a layer height.
When you use variable layers, set top surfaces by thickness, not layer count. Prusa notes that its "minimum wall thickness" setting is especially useful with variable layer height. On terrain, the top skin is spread across every slope, so a skin that is too thin lets infill show on the hillsides.
Resin
Resin printers use much thinner layers. Formlabs lists layer thickness of 25 to 200 microns for the Form 4 and 25 to 250 microns for the Form Studio 1 Maker spec; other printers have their own ranges. Use the layer heights your printer and resin profile offer. A large flat terrain slab is a hard shape on a resin printer, so read resin orientation and supports before printing one, and handle the resin as its SDS states.
A starting plan
- Base down. Starting point
- A mid-range layer height for your nozzle, with variable layer height on and smoothed.
- Top skin set by thickness so infill cannot show through on slopes.
- Print a small tile from the flattest part of your map, look at it in raking light, then adjust layer height before printing the full set.
- Variable layer height function Prusa Research
- Layers and perimeters Prusa Research
- Layer height Polymaker Wiki
- Compare Formlabs SLA 3D Printers' Tech Specs Formlabs
Last reviewed 2026-11-05