Lakes Terrain Viewer — Provenance & Method

A LIDAR-derived map of the Lake District and Eden Valley, rendered as interactive terrain art. This page sets out where the data comes from, how the visuals are made, and how to read what you're looking at.

Coverage

Source data

Elevation comes from the Environment Agency National LIDAR Programme composite DTM (2022) — the most complete public 1-metre LIDAR dataset for England. The 65 × 65 km window was extracted from the national tile mosaic, hole-filled where needed, and stored as a Cloud-Optimised GeoTIFF so the viewer can fetch elevation along any profile line on demand.

The composite DTM is published under the Open Government Licence v3.0 by the Environment Agency. Attribution is shown on the viewer's footer.

How the visuals are made

The map you see is not a photograph — it is a hill-shaded rendering of the elevation data. The 1-metre DTM is processed offline into a 13,000-pixel square colour image for each palette. The viewer streams the chosen palette as a single WebP (≈ 14 MB) and the browser scales it smoothly as you pan and zoom.

Fourteen palettes are currently available. They share the same underlying elevation but apply different hypsometric tints — the cartographic tradition of colouring land by height:

• Hillshade — pure grey relief, for ridge-line reading
• Imhof — the Swiss alpine gradient first published by Eduard Imhof in 1962
• Spectral — a high-saturation rainbow for fast peak / valley scanning
• Lakes A, B, C — purpose-built palettes for the Lakes landscape: bands & contours / Moiré beat / sub-tint layered
• Wild & Wild Smooth — an Aurora Borealis colour scheme, banded and continuous
• Summer, Winter, Special — seasonal and painterly variants (the Special palette is loosely after Heaton Cooper and Ruskin watercolours)
• Earth Body, Granite Body, Jewel Body — isoluminant palettes that read the whole landform as one continuous mass

Profiles

Drawing a line with the profile tool generates an elevation cross-section. For profiles up to about 5 km the line is sent to a Cloudflare Worker, which reads the 1-metre COG directly via HTTP byte-range requests and returns the sampled elevations in well under a second. Longer profiles fall back to client-side reads of the same COG. Either way, the elevations you see are sampled at the data's native 1-metre resolution, not from the 5-metre visual layer.

Scene render

The viewpoint tool drops a pin at a chosen ground point. With a bearing set on the compass, the Scene Render button runs an oblique 3-D ray-march from a 1.75-metre eye-height standpoint, sampling the 1-metre DTM for the terrain geometry and the chosen palette for surface colour. The output is a 4K PNG which can be saved with a metadata strip listing the coordinates, bearing, palette and source lineage.

What you should not read into it

The viewer is a cartographic interpretation, not a survey instrument. Elevations are accurate to the 1-metre LIDAR composite (typical RMSE well below 0.5 m for open ground), but no walking route, climbing decision or surveying judgement should be made from it without cross-referencing the Ordnance Survey maps and your own observation of the ground. Lake surfaces and dense forest canopies are simplified by the underlying composite.

Credits