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Aldebrn Maps: texture-shaded terrain visualization

A usage guide by Ahmed Fasih 2015/12/14

Texture shading is a rarely-used but powerfully-evocative way to visualize terrain. My Aldebrn Maps web app lets you explore most of our world’s stunning elevation diversity. Here’s how to use it.

Example of view in Aldebrn Maps
The Basin and Range Province (USGS), a closeup. “Paradox Valley,” “Disappointment Valley,” “Outlaw Mesa”…

Bookmarks

  1. Japan: Mountains and Light. 日本、山と光
  2. Constellation of four mountains in the Pacific Northwest
  3. Visualizing Sydney, NSW, Australia and its foothills

Introduction

When you first visit Japan: Mountains and Light in Aldebrn Maps with a WebGL-enabled browser, you’ll see something like this.

This is Cesium.js, an open-source 3D globe that runs in your browser. Feel free to drag the globe around to pan, zoom, or rotate with your mouse, trackpad, or touchscreen: at the upper-right is a description of how to do all of these on various devices.

This particular globe gives examines the twin forces of urbanization and terrain, and their effect on the Japanese archipelago. It superimposes texture-shaded terrain, on top of the NASA Black Marble, which shows the lights seen at night from space (NASA).

This document won’t discuss texture-shading or fractional-Laplacian filtering, rather it will just show how to start getting the most out of this Cesium app.

Basic Usage

Try this: click on the button immediately to the left of the question mark, pointed at by the red arrow.


Click the second-from-left button (pointed at by the arrow) to select another base layer instead of the Black Marble “nightlights”.

This will pop out Cesium’s basemap selection palette. These are all the maps you can replace the Black Marble with, including road maps from Bing or OpenStreetMap, satellite imagery from Mapbox or Bing, even the very informative National Geographic map.

Next, consider the slider bars at the left. These give you a number of ways to manipulate the basemap or the terrain texture (“tex”). For either you can dial up or down the brightness, contrast, and gamma correction. You can also adjust the basemap’s hue and saturation, or the terrain texture’s alpha transparency. This last allows you to focus exclusively on the terrain (alpha=1.0) or make it completely disappear (alpha=0.0); all values in between allow partial transparency.

Sharing

When you find a view that you wish to share, click the “Permalink” button beneath the sliders. That will update the URL with a permalink to the current view, and includes your choice of basemap and any image quality parameters:


The “Permalink” button updates your browser’s URL with a link to the current view.

You can now copy the URL and paste it into Twitter, etc. My apologies—currently the URL is extremely long because of how simple-mindedly I’m generating it, so a link shortener is advised.

Further reading

Terrain texture-shading is the brainchild of Leland Brown (TextureShading), whose website and two presentations, from 2010 and 2014 (Box), provide more cartographic and technical background on the technique.