Wireframe from the real USGS 10m DEM, sampled over the route's
own bounding box + 15% margin — a fresh sample per route, not shared
across tabs. Height is real metres; the surface is drawn at
2.2× vertical exaggeration so grade reads as texture rather
than flattening to nothing — a slope drawn steeper than this would be a
claim about the ground that isn't true, so the factor is stated here rather
than hidden. No street labels: this view is for shape and terrain, not
navigation — the 2D card keeps that job. Drag to rotate around the
route; the whole loop stays framed at every angle. SCRUB previews the
ghost/lit reveal — which part of the route is already covered —
independent of the camera.