A canvas with a transparent background.

100% © U.S. Geological Survey

You can render Giro3D's scene on a transparent background, using the appropriate options in the Instance constructor.

index.js
import colormap from 'colormap';

import { Color } from 'three';
import { MapControls } from 'three/examples/jsm/controls/MapControls.js';

import XYZ from 'ol/source/XYZ.js';

import Extent from '@giro3d/giro3d/core/geographic/Extent.js';
import Instance from '@giro3d/giro3d/core/Instance.js';
import ElevationLayer from '@giro3d/giro3d/core/layer/ElevationLayer.js';
import Map from '@giro3d/giro3d/entities/Map.js';
import GeoTIFFFormat from '@giro3d/giro3d/formats/GeoTIFFFormat.js';
import ColorMap, { ColorMapMode } from '@giro3d/giro3d/core/layer/ColorMap.js';
import TiledImageSource from '@giro3d/giro3d/sources/TiledImageSource.js';
import Inspector from '@giro3d/giro3d/gui/Inspector.js';

const x = -13602000;
const y = 5812000;
const halfWidth = 2500;

// Defines geographic extent: CRS, min/max X, min/max Y
const extent = new Extent('EPSG:3857', x - halfWidth, x + halfWidth, y - halfWidth, y + halfWidth);

const viewerDiv = document.getElementById('viewerDiv');

const instance = new Instance(viewerDiv, {
    crs: extent.crs(),
    renderer: {
        clearColor: false,
    },
});

const map = new Map('planar', {
    extent,
    hillshading: true,
    doubleSided: true,
    backgroundColor: 'white',
});

instance.add(map);

const source = new TiledImageSource({
    source: new XYZ({
        minZoom: 10,
        maxZoom: 16,
        url: 'https://3d.oslandia.com/dem/MtStHelens-tiles/{z}/{x}/{y}.tif',
    }),
    format: new GeoTIFFFormat(),
});

const floor = 1100;
const ceiling = 2500;

const values = colormap({ colormap: 'viridis', nshades: 256 });
const colors = values.map(v => new Color(v));

const dem = new ElevationLayer({
    name: 'dem',
    source,
    extent,
    colorMap: new ColorMap(colors, floor, ceiling, ColorMapMode.Elevation),
});

map.addLayer(dem);

instance.camera.camera3D.position.set(-13594700, 5819700, 7300);

const controls = new MapControls(instance.camera.camera3D, instance.domElement);

controls.target.set(-13603000, 5811000, 0);

instance.useTHREEControls(controls);

instance.notifyChange();

Inspector.attach(document.getElementById('panelDiv'), instance);
index.html
<!doctype html>
<html lang="en">
    <head>
        <title>Transparent canvas background</title>
        <meta charset="UTF-8" />
        <meta name="name" content="transparent_background" />
        <meta name="description" content="A canvas with a transparent background." />
        <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"
        />

        <style>
        #viewerDiv canvas {
          background-image: linear-gradient(45deg, #aaaaaa 25%, transparent 25%),
            linear-gradient(-45deg, #aaaaaa 25%, transparent 25%),
            linear-gradient(45deg, transparent 75%, #aaaaaa 75%),
            linear-gradient(-45deg, transparent 75%, #aaaaaa 75%);
          background-size: 20px 20px;
          background-position:
            0 0,
            0 10px,
            10px -10px,
            -10px 0px;
        }
        </style>
    </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>

        

        <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": "transparent_background",
    "dependencies": {
        "colormap": "^2.3.2",
        "@giro3d/giro3d": "0.37.2"
    },
    "devDependencies": {
        "vite": "^3.2.3"
    },
    "scripts": {
        "start": "vite",
        "build": "vite build"
    }
}