Build a CNC-Routed Topographic Relief Map from Real Elevation Data

Topographic relief maps — real terrain, carved to scale, with the mountains actually standing proud of the valleys — are one of the most satisfying things you can put on a CNC router. Unlike a V-carved sign or a flat inlay, a relief map uses genuine 3D toolpaths driven by real elevation data, so the final piece is scientifically accurate to the landscape it represents: your home mountain, a favorite lake, a ski resort, or a stretch of coastline. This project walks through pulling real elevation data, converting it into a machinable heightmap, and roughing and finishing the carve on a desktop CNC router like the Wolfpawn 4040 Pro.

How It Works

A relief map is machined from a digital elevation model (DEM) — a grid of elevation values covering a geographic area. CAM software (or a purpose-built relief toolpath generator) reads that grid as a grayscale heightmap, where brightness corresponds to elevation, and generates a 3D roughing and finishing toolpath that literally carves the terrain into a wood or foam blank. The result is a physical, to-scale model of real topography, not an artistic approximation.

Safety Notes

This project is lower-risk than most CNC work, but a few points matter: 3D relief carving runs long, often multiple hours unattended — never leave a CNC router running in an unoccupied space, and consider an automatic fire detection/shutdown setup if you run long jobs regularly. Ball-nose finishing passes at shallow stepover generate a lot of fine dust; run dust collection and wear a proper respirator, especially in MDF or engineered wood blanks. Basswood and eastern white pine are pleasant to carve but still produce wood dust that should never be treated as harmless.

Parts List

• Basswood or eastern white pine carving blank, sized to bed
• Baltic birch plywood backer/base board
• Ball-nose end mill set (1/4in and 1/8in) for 3D finishing passes
• Tapered ball-nose bit for deep-valley detail
• Double-sided carpet tape or CA glue for workholding
• Danish oil or wipe-on wood finish
• Float-mount frame or display stand hardware
• Dust shoe and dust collection hose for the router

Step 1: Source Real Elevation Data

Free, high-resolution elevation data is available for nearly anywhere on Earth:

• USGS 3D Elevation Program (3DEP) — 1/3 arc-second (roughly 10m) or better resolution DEMs for the United States, free through The National Map viewer.
• OpenTopography.org — free global DEMs including SRTM (30m global coverage) and higher-resolution regional LiDAR datasets.
• Copernicus GLO-30 — free 30m global DEM covering the entire planet, useful for international locations.

Download a GeoTIFF covering your area of interest, then crop it to the exact bounding box you want to carve using free GIS software like QGIS. Note the real-world dimensions of your cropped area (in kilometers or miles) — you'll need this to calculate your carve's horizontal scale.

Step 2: Convert Elevation Data to a Machinable Heightmap

Most CAM packages that support 3D relief carving (Vectric Aspire, Fusion 360, or dedicated tools) accept a grayscale heightmap image rather than a raw GeoTIFF. In QGIS, use the raster renderer to export your cropped DEM as an 8-bit or 16-bit grayscale PNG or BMP, stretching the elevation range across the full black-to-white range for maximum vertical resolution. A 16-bit heightmap preserves far more elevation detail than 8-bit and is worth the extra step if your CAM software supports it.

Decide your vertical exaggeration now. Real terrain is often visually underwhelming at true 1:1 vertical-to-horizontal scale on a small carve — a mountain that's dramatic in person might only be a few millimeters of relief on a 12-inch board. Most relief carvers exaggerate vertical scale 1.5x–3x over true scale to make the terrain read clearly; note whatever factor you use in your CAM setup so the heightmap-to-Z-depth mapping matches it.

Step 3: Generate Roughing and Finishing Toolpaths

Import the heightmap into your CAM software's 3D relief module and set your model size to match your blank, honoring the horizontal scale you calculated from real-world dimensions in Step 1.

• Roughing pass: a larger flat-end or ball-nose bit (1/4in) clearing bulk material with generous stepover (40–50% of bit diameter) and a stepdown appropriate to your material — this pass is about speed, not finish.
• Finishing pass: a smaller ball-nose bit (1/8in or smaller) with tight stepover (10–15% of bit diameter) for a smooth surface across the whole terrain — this is the pass that determines final quality and takes the bulk of your machine time.
• For deep, narrow valleys or canyons, add a rest-machining or "pencil" finishing pass with a tapered ball-nose bit to reach detail the larger finishing bit can't access.

Run a full toolpath simulation before cutting — relief carves are long jobs, and catching a collision or an out-of-bounds Z-depth in simulation beats catching it three hours into a cut.

Step 4: Workholding and the Cut

Because the finishing pass runs long and touches the entire surface, workholding has to survive the full job without shifting. Double-sided tape around the perimeter (outside your final carved area, since it will be removed anyway) combined with tabs or a sacrificial spoilboard fence works well for basswood and pine blanks. Square and zero your stock carefully — a relief map with a tilted Z-zero will read as visibly warped terrain even if every individual toolpath ran correctly.

Expect roughing to run 20–60 minutes depending on blank size, and finishing to run considerably longer — multi-hour finishing passes are normal for anything larger than about 8x10 inches at a fine stepover. This is exactly the kind of unattended long-running job where automatic fire detection and shutdown hardware earns its keep.

Step 5: Finishing the Piece

Once the carve is done, lightly hand-sand any fuzz left by the finishing pass — a fine-grit sanding sponge conforms to the terrain better than a flat sanding block. A wipe-on Danish oil or clear finish brings out grain and adds depth to the shadows in the terrain without obscuring detail; avoid heavy film finishes like polyurethane, which can pool in valleys and look uneven. Mount on a baltic birch backer board or in a float-mount frame that lets the terrain's high points sit slightly proud of the frame edge for a display-ready piece.

Common Pitfalls

ProblemCauseFix Terrain looks flat/uninterestingNo vertical exaggeration appliedRe-export heightmap with 1.5x–3x Z scaling before generating toolpaths Visible stepping/banding on slopesFinishing stepover too coarseDrop stepover to 10% or less of finishing bit diameter, accept the longer runtime Piece looks warped after carvingStock not flat, or Z-zero set on an uneven spotSurface the blank flat first; zero from a known-flat reference point, not the terrain itself Deep valleys left un-machinedBall-nose bit diameter too large to reach narrow featuresAdd a rest-machining pass with a smaller tapered ball-nose bit

A relief map built from real elevation data is a genuinely different category of CNC project from V-carved signage — it's a small act of cartography as much as woodworking, and it's one of the few desktop CNC projects where the "3D" in your CAM software's 3D toolpath actually means something scientifically real.