Illustrates how textures are allocated when layers have a lot of empty areas.

100% © Métropole Grand Lyon

Tiles in red do not contain any allocated texture because the layer only produces transparent pixels for this area.

index.js 
import { MapControls } from "three/examples/jsm/controls/MapControls.js";

import Extent from "@giro3d/giro3d/core/geographic/Extent.js";
import GeoTIFFSource from "@giro3d/giro3d/sources/GeoTIFFSource.js";
import Instance from "@giro3d/giro3d/core/Instance.js";
import ColorLayer from "@giro3d/giro3d/core/layer/ColorLayer.js";
import Map from "@giro3d/giro3d/entities/Map.js";
import Inspector from "@giro3d/giro3d/gui/Inspector.js";
import Interpretation from "@giro3d/giro3d/core/layer/Interpretation.js";

import { DoubleSide } from "three";

Instance.registerCRS(
  "EPSG:26910",
  "+proj=utm +zone=10 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs +type=crs",
);

const extent = new Extent("EPSG:26910", 532622, 569790, 5114416, 5137240);

const center = extent.centerAsVector3();

const instance = new Instance({
  target: "view",
  crs: extent.crs,
  backgroundColor: "gray",
});

instance.view.camera.position.set(center.x, center.y - 1, 50000);

const controls = new MapControls(instance.view.camera, instance.domElement);
controls.enableDamping = true;
controls.dampingFactor = 0.2;
controls.target.set(center.x, center.y, center.z);
instance.view.setControls(controls);

const source = new GeoTIFFSource({
  url: "https://3d.oslandia.com/dem/msh2009dem.tif",
  crs: extent.crs,
});

const map = new Map({
  extent,
  side: DoubleSide,
  showOutline: true,
});

instance.add(map);

const min = 227;
const max = 2538;

const layer = new ColorLayer({
  source,
  showEmptyTextures: true,
  interpretation: Interpretation.CompressTo8Bit(min, max),
});

map.addLayer(layer);

Inspector.attach("inspector", instance);
index.html 
<!doctype html>
<html lang="en">
  <head>
    <title>Sparse layers</title>
    <meta charset="UTF-8" />
    <meta name="name" content="sparse_layers" />
    <meta
      name="description"
      content="Illustrates how textures are allocated when layers have a lot of empty areas."
    />
    <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/examples/css/example.css"
    />
  </head>

  <body>
    <div id="view" class="m-0 p-0 w-100 h-100"></div>
    <div
      id="inspector"
      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": "sparse_layers",
    "dependencies": {
        "@giro3d/giro3d": "0.41.0"
    },
    "devDependencies": {
        "vite": "^3.2.3"
    },
    "scripts": {
        "start": "vite",
        "build": "vite build"
    }
}