COG image manipulation

Select which bands to view on COGs with multiple bands.

Channel mapping

100% © Data provided by the European Space Agency

COGs may have multiple bands. You can select which bands to view, and specify how to map them to regular R, G, B colors.

index.js

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 Interpretation from '@giro3d/giro3d/core/layer/Interpretation.js';
import Map from '@giro3d/giro3d/entities/Map.js';
import Inspector from '@giro3d/giro3d/gui/Inspector.js';



Instance.registerCRS('EPSG:32611', '+proj=utm +zone=11 +datum=WGS84 +units=m +no_defs +type=crs');

// Define geographic extent: CRS, min/max X, min/max Y
const extent = new Extent('EPSG:32611', 666285, 668533.5, 3997174, 3998444);
const center = extent.centerAsVector3();

// `viewerDiv` will contain Giro3D' rendering area (the canvas element)
const viewerDiv = document.getElementById('viewerDiv');

// Instantiate Giro3D
const instance = new Instance(viewerDiv, {
    crs: extent.crs(),
    renderer: {
        clearColor: 0x0a3b59,
    },
});

// Instantiate the camera
instance.camera.camera3D.position.set(center.x, center.y, 2500);

// Instantiate the controls
const controls = new MapControls(instance.camera.camera3D, instance.domElement);
controls.enableDamping = true;
controls.dampingFactor = 0.2;
controls.target.set(center.x, center.y + 1, center.z);

instance.useTHREEControls(controls);

// Construct a map and add it to the instance
const map = new Map('planar', { extent });
instance.add(map);

const channels = [0, 1, 2];

function createLayer() {
    // Data coming from the same source as
    // https://openlayers.org/en/latest/examples/cog-math-multisource.html
    const source = new CogSource({
        url: 'https://3d.oslandia.com/cog_data/20200428_211318_ssc8d1_0017_pansharpened.cog.tif',
        crs: extent.crs(),
        channels,
    });
    return new ColorLayer({
        name: 'color-layer',
        source,
        extent,
        interpretation: Interpretation.CompressTo8Bit(0, 900),
    });
}

let layer = createLayer();
map.addLayer(layer);

function bindDropdown(id, action) {
    document.getElementById(id).addEventListener('change', e => {
        const value = parseInt(e.target.value, 10);
        action(value);
        map.removeLayer(layer, { disposeLayer: true });
        layer = createLayer();
        map.addLayer(layer);
    });
}

bindDropdown('r-channel', v => {
    channels[0] = v;
});
bindDropdown('g-channel', v => {
    channels[1] = v;
});
bindDropdown('b-channel', v => {
    channels[2] = v;
});

Inspector.attach(document.getElementById('panelDiv'), instance);

index.html

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <title>Giro3D - COG image manipulation</title>
  <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.2/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-T3c6CoIi6uLrA9TneNEoa7RxnatzjcDSCmG1MXxSR1GAsXEV/Dwwykc2MPK8M2HN" crossorigin="anonymous">
  <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap-icons@1.11.3/font/bootstrap-icons.min.css">
  <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.2/dist/js/bootstrap.bundle.min.js" integrity="sha384-C6RzsynM9kWDrMNeT87bh95OGNyZPhcTNXj1NW7RuBCsyN/o0jlpcV8Qyq46cDfL" crossorigin="anonymous"></script>
  <style>
    body {
      padding: 0;
      margin: 0;
      width: 100vw;
      height: 100vh;
    }

    #viewerDiv {
      width: 100%;
      height: 100%;
    }

    #panelDiv {
      position: absolute;
      top: 0;
      left: 0;
    }
    
  </style>
</head>

<body>
  <div id="viewerDiv"></div>
  <div id="panelDiv"></div>
  <div class="m-2 position-absolute top-0 end-0">
    <div class="card">
        <div class="card-body">
            <!-- Mapping -->
            <form>
                <fieldset>
                    <legend>Channel mapping</legend>

                    <div class="input-group mb-3">
                        <label class="input-group-text" for="r-channel">R</label>
                        <select class="form-select" id="r-channel">
                            <option value="0" selected>Band 1</option>
                            <option value="1">Band 2</option>
                            <option value="2">Band 3</option>
                            <option value="3">Band 4</option>
                        </select>
                    </div>
                    <div class="input-group mb-3">
                        <label class="input-group-text" for="g-channel">G</label>
                        <select class="form-select" id="g-channel">
                            <option value="0">Band 1</option>
                            <option value="1" selected>Band 2</option>
                            <option value="2">Band 3</option>
                            <option value="3">Band 4</option>
                        </select>
                    </div>
                    <div class="input-group mb-3">
                        <label class="input-group-text" for="b-channel">B</label>
                        <select class="form-select" id="b-channel">
                            <option value="0" selected>Band 1</option>
                            <option value="1">Band 2</option>
                            <option value="2" selected>Band 3</option>
                            <option value="3">Band 4</option>
                        </select>
                    </div>
                </fieldset>
            </form>
        </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>

package.json

{
  "name": "cog_channel_mapping",
  "dependencies": {
    "@giro3d/giro3d": "0.35.0"
  },
  "devDependencies": {
    "vite": "^3.2.3"
  },
  "scripts": {
    "start": "vite",
    "build": "vite build"
  }
}