Vertical Exaggeration and Terrain Scale

Horizontal scale first

Decide how big the print is, then everything else follows. Use the same units on both sides (convert kilometers or meters to millimeters).

If the area is not square, compute the scale from the side that has to fit the bed, then apply the same scale to the other side so the map is not stretched.

Vertical scale and printed height

At true scale the vertical scale equals the horizontal scale. Vertical exaggeration is a multiplier on top of that.

That example shows why true-scale terrain often disappoints: a whole mountain range rises 10 mm on a 200 mm tile. Flat country is worse. A plain with 50 m of relief at the same scale rises a third of a millimeter, which is fewer than two 0.2 mm layers Formula.

Blender's Displace modifier does not take an exaggeration factor directly. The manual gives displacement = texture value minus Midlevel, and vertex offset = displacement × Strength, so Strength is the full height of the terrain in scene units. With Midlevel at 0, set Strength = relief height × vertical scale, in scene units (for the example above at 2x, 20 mm). A negative Strength inverts the surface. Other tools may ask for a Z scale, height multiplier or exaggeration factor instead; read which one yours wants, and check the printed height in the slicer before you print.

What exaggeration does to slopes

Exaggeration does not only make things taller. It multiplies the steepness of every slope:

That has three practical effects:

• Steeper slopes print with smaller stair-steps on FDM and resin, because each layer steps sideways less on a steep surface. See orientation and layer height for terrain.
• Peaks turn into spikes at high factors. Ridges and summits read as needles, and data errors that were invisible at 1x stand out (see common terrain failures).
• The model stops being a measurement. Label an exaggerated model with its factor (for example "vertical exaggeration 2x") if anyone will read heights off it.

Measure it There is no correct factor. It depends on how much relief the area has, how big the print is and what the model is for. Print a small test tile of the steepest and flattest parts at two or three factors and compare them in raking light before committing to a large print.

Does your printer show the data's resolution?

The DEM's cell size, scaled down, tells you how far apart the data points sit on the print.

USGS gives 3DEP 1/3 arc-second data as about 10 m spacing and 1 arc-second as about 30 m Maker spec; SRTM 1 arc-second global is about 30 m Maker spec. In the example, even 30 m data puts points 0.2 mm apart, half the width of a 0.4 mm nozzle opening Formula. Finer data at that scale adds triangles and file size without adding anything the printer can draw. The finer datasets earn their keep on small areas printed large: a single valley or a park, not a state.

Working the other way, the number of cells across the print is real width divided by cell size. 30 km of 30 m data is 1,000 cells across, which is already a dense mesh. If the file is too heavy for your software, resample it to fewer cells, keeping the printed cell size at or below what your printer can resolve.

A worked setup

1. Choose the print size that fits your bed, or plan tiles (splitting large terrain).
2. Compute the horizontal scale.
3. Find the lowest and highest elevation in the crop and compute terrain height at 1x.
4. If that height is only a few millimeters, try exaggeration; if it is already tall, leave it at 1x.
5. Add the base (bases and thickness) and check the total height in the slicer.