Display an elevation COG with a color map.
A COG that contains elevation data in 32-bit floating point values. You can visualize the dataset in the following ways: as an elevation layer with or without a color map, as a color layer compressed to 8-bit using Interpretation.CompressTo8Bit, and as a color layer with a ColorMap.
import colormap from 'colormap';
import { Color } from 'three';
import { MapControls } from 'three/examples/jsm/controls/MapControls.js';
import Extent from '@giro3d/giro3d/core/geographic/Extent.js';
import CogSource from '@giro3d/giro3d/sources/CogSource.js';
import Instance from '@giro3d/giro3d/core/Instance.js';
import ColorLayer from '@giro3d/giro3d/core/layer/ColorLayer.js';
import ElevationLayer from '@giro3d/giro3d/core/layer/ElevationLayer.js';
import Interpretation from '@giro3d/giro3d/core/layer/Interpretation.js';
import Map from '@giro3d/giro3d/entities/Map.js';
import Inspector from '@giro3d/giro3d/gui/Inspector.js';
import ColorMap, { ColorMapMode } from '@giro3d/giro3d/core/layer/ColorMap.js';
const extent = new Extent('EPSG:3857', -13581040.085, -13469591.026, 5780261.83, 5942165.048);
// `viewerDiv` will contain Giro3D' rendering area (the canvas element)
const viewerDiv = document.getElementById('viewerDiv');
// Instantiate Giro3D
const instance = new Instance(viewerDiv, {
crs: extent.crs(),
});
// Instantiate the camera
instance.camera.camera3D.position.set(-13656319, 5735451, 88934);
// Instantiate the controls
const controls = new MapControls(instance.camera.camera3D, instance.domElement);
controls.enableDamping = true;
controls.dampingFactor = 0.2;
controls.target.set(-13545408, 5837154, 0);
instance.useTHREEControls(controls);
// Construct a map and add it to the instance
const map = new Map('planar', {
extent,
backgroundColor: 'gray',
hillshading: true,
});
instance.add(map);
// Use an elevation COG with nodata values
const source = new CogSource({
// https://www.sciencebase.gov/catalog/item/632a9a9ad34e71c6d67b95a3
url: 'https://3d.oslandia.com/cog_data/COG_EPSG3857_USGS_13_n47w122_20220919.tif',
crs: extent.crs(),
});
function makeColorMap(name) {
return colormap({ colormap: name, nshades: 256 }).map(v => new Color(v));
}
const min = 263;
const max = 4347;
// Display it as elevation and color
const viridis = new ColorMap(makeColorMap('viridis'), min, max, ColorMapMode.Elevation);
const magma = new ColorMap(makeColorMap('magma'), min, max, ColorMapMode.Elevation);
// Attach the inspector
Inspector.attach(document.getElementById('panelDiv'), instance);
function updateMode(value) {
map.removeLayer(map.getLayers()[0]);
switch (value) {
case 'elevation-colormap':
map.addLayer(
new ElevationLayer({
name: value,
extent,
source,
colorMap: viridis,
minmax: { min, max },
}),
);
break;
case 'elevation':
map.addLayer(
new ElevationLayer({
name: value,
extent,
source,
minmax: { min, max },
}),
);
break;
case '8bit':
map.addLayer(
new ColorLayer({
name: value,
extent,
source,
interpretation: Interpretation.CompressTo8Bit(min, max),
}),
);
break;
case 'colormap':
map.addLayer(
new ColorLayer({
name: value,
extent,
source,
colorMap: magma,
}),
);
break;
default:
break;
}
instance.notifyChange(map);
}
const mode = document.getElementById('mode');
mode.onchange = () => updateMode(mode.value);
updateMode(mode.value);<!doctype html>
<html lang="en">
<head>
<title>Elevation COG</title>
<meta charset="UTF-8" />
<meta name="name" content="cog_elevation" />
<meta name="description" content="Display an elevation COG with a color map." />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<link rel="icon" href="https://giro3d.org/images/favicon.svg" />
<link href="https://giro3d.org/assets/bootstrap-custom.css" rel="stylesheet" />
<script src="https://giro3d.org/assets/bootstrap.bundle.min.js"></script>
<link
rel="stylesheet"
type="text/css"
href="https://giro3d.org/latest/css/example.css"
/>
</head>
<body>
<div id="viewerDiv" class="m-0 p-0 w-100 h-100"></div>
<div id="panelDiv" class="position-absolute top-0 start-0 mh-100 overflow-auto"></div>
<div class="side-pane-with-status-bar">
<!-- Top color layer -->
<div class="card">
<div class="card-body">
<div class="input-group">
<span class="input-group-text flex-grow-1">Read COG as</span>
<select class="btn btn-outline-primary btn-sm" id="mode" autocomplete="off">
<option selected value="elevation">Elevation layer</option>
<option value="elevation-colormap">Elevation layer (with colormap)</option>
<option value="8bit">Color layer (compressed to 8-bit)</option>
<option value="colormap">Color layer (with colormap)</option>
</select>
</div>
</div>
</div>
</div>
<script type="module" src="index.js"></script>
<script>
/* activate popovers */
const popoverTriggerList = [].slice.call(
document.querySelectorAll('[data-bs-toggle="popover"]'),
);
popoverTriggerList.map(
// bootstrap is used as script in the template, disable warning about undef
// eslint-disable-next-line no-undef
popoverTriggerEl =>
new bootstrap.Popover(popoverTriggerEl, {
trigger: 'hover',
placement: 'left',
content: document.getElementById(
popoverTriggerEl.getAttribute('data-bs-content'),
).innerHTML,
html: true,
}),
);
</script>
</body>
</html>{
"name": "cog_elevation",
"dependencies": {
"colormap": "^2.3.2",
"@giro3d/giro3d": "0.37.3"
},
"devDependencies": {
"vite": "^3.2.3"
},
"scripts": {
"start": "vite",
"build": "vite build"
}
}