Display a classified point cloud.

Options
Classifications
100% © IGN

To make use of classification data available in a point cloud (in this example, a 3D Tiles point cloud), we have to use a custom PointCloudMaterial. Updating a classification (color and visibility) is done directly on this material with the .classifications property.

index.js
import { Color } from "three";
import { MapControls } from "three/examples/jsm/controls/MapControls.js";
import { CSS2DObject } from "three/examples/jsm/renderers/CSS2DRenderer.js";

import Instance from "@giro3d/giro3d/core/Instance.js";
import Tiles3D from "@giro3d/giro3d/entities/Tiles3D.js";
import Tiles3DSource from "@giro3d/giro3d/sources/Tiles3DSource.js";
import Inspector from "@giro3d/giro3d/gui/Inspector.js";
import PointCloudMaterial, {
  MODE,
} from "@giro3d/giro3d/renderer/PointCloudMaterial.js";

function bindSlider(id, onChange) {
  const element = document.getElementById(id);
  if (!(element instanceof HTMLInputElement)) {
    throw new Error(
      "invalid binding element: expected HTMLInputElement, got: " +
        element.constructor.name,
    );
  }

  element.oninput = function oninput() {
    onChange(element.valueAsNumber);
  };

  const setValue = (v) => {
    element.valueAsNumber = v;
    onChange(element.valueAsNumber);
  };

  const initialValue = element.valueAsNumber;

  return [setValue, initialValue, element];
}

function bindToggle(id, onChange) {
  const element = document.getElementById(id);
  if (!(element instanceof HTMLInputElement)) {
    throw new Error(
      "invalid binding element: expected HTMLButtonElement, got: " +
        element.constructor.name,
    );
  }

  element.oninput = function oninput() {
    onChange(element.checked);
  };

  const callback = (v) => {
    element.checked = v;
    onChange(element.checked);
  };

  return [callback, element.checked, element];
}

function bindColorPicker(id, onChange) {
  const element = document.getElementById(id);
  if (!(element instanceof HTMLInputElement)) {
    throw new Error(
      "invalid binding element: expected HTMLInputElement, got: " +
        element.constructor.name,
    );
  }

  element.oninput = function oninput() {
    // Let's change the classification color with the color picker value
    const hexColor = element.value;
    onChange(new Color(hexColor));
  };

  const externalFunction = (v) => {
    element.value = `#${new Color(v).getHexString()}`;
    onChange(element.value);
  };

  return [externalFunction, new Color(element.value), element];
}

Instance.registerCRS(
  "EPSG:2154",
  "+proj=lcc +lat_0=46.5 +lon_0=3 +lat_1=49 +lat_2=44 +x_0=700000 +y_0=6600000 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs +type=crs",
);

const instance = new Instance({
  target: "view",
  crs: "EPSG:2154",
  backgroundColor: null, // To make the canvas transparent and show the actual CSS background
});

// Enables post-processing effects to improve readability of point cloud.
instance.renderingOptions.enableEDL = true;
instance.renderingOptions.enableInpainting = true;
instance.renderingOptions.enablePointCloudOcclusion = true;

instance.view.camera.position.set(227137, 6876151, 128);

const controls = new MapControls(instance.view.camera, instance.domElement);
controls.enableDamping = true;
controls.dampingFactor = 0.2;
controls.target.set(227423, 6876442, 0);
controls.saveState();
instance.view.setControls(controls);

// We create a PointCloudMaterial in CLASSIFICATION
// mode to display the point classifications.
const material = new PointCloudMaterial({ mode: MODE.CLASSIFICATION });

// The material provides default colors for classifications 0-63,
// i.e the reserved range for ASPRS classifications.
// Classifications in the 64-255 range are user-defined.

material.classifications[64].color = new Color(0x94a770); // Classification "Sursol pérenne"
material.classifications[65].color = new Color(0xd3ff00); // Classification "Artefacts"
material.classifications[66].color = new Color(0x00ff8d); // Classification "Points virtuels"

// Original dataset extracted from the French IGN LIDAR HD
// database (https://geoservices.ign.fr/lidarhd#telechargementclassifiees),
// then converted to 3D Tiles with py3dtiles (https://gitlab.com/py3dtiles/py3dtiles)
const url =
  "https://3d.oslandia.com/giro3d/3d-tiles/LHD_FXX_0227_6877_PTS_C_LAMB93_IGN69/tileset.json";

const pointcloud = new Tiles3D(new Tiles3DSource(url), {
  material,
});

instance.add(pointcloud);

const classificationNames = new Array(32);

// GUI controls for classification handling

function addClassification(number, name) {
  const currentColor = material.classifications[number].color.getHexString();

  const template = `
    <div class="form-check form-switch">
        <input
            class="form-check-input"
            type="checkbox"
            checked
            role="switch"
            id="class-${number}"
            autocomplete="off"
        />
        <label class="form-check-label w-100" for="class-${number}">
            <div class="row">
                <div class="col" >${name}</div>
                <div class="col-auto">
                    <input
                        type="color"
                        style="height: 1.5rem"
                        class="form-control form-control-color float-end"
                        id="color-${number}"
                        value="#${currentColor}"
                        title="Classification color"
                    />
                </div>
            </div>
        </label>
    </div>
    `;

  const node = document.createElement("div");
  node.innerHTML = template;
  document.getElementById("classifications").appendChild(node);

  // Let's change the classification color with the color picker value
  bindColorPicker(`color-${number}`, (v) => {
    // Parse it into a THREE.js color
    const color = new Color(v);

    material.classifications[number].color = color;

    instance.notifyChange();
  });

  classificationNames[number] = name;

  bindToggle(`class-${number}`, (enabled) => {
    // By toggling the .visible property of a classification,
    // all points that have this classification are hidden/shown.
    material.classifications[number].visible = enabled;
    instance.notifyChange();
  });
}

// Standard ASPRS classifications found in the dataset
addClassification(1, "Unclassified");
addClassification(2, "Ground");
addClassification(3, "Low vegetation");
addClassification(4, "Medium vegetation");
addClassification(5, "High vegetation");
addClassification(6, "Building");
addClassification(9, "Water");

// Dataset-specific classifications
addClassification(64, "Permanent above-ground structures");
addClassification(65, "Artifacts");
addClassification(67, "Virtual points");

const labelElement = document.createElement("div");
labelElement.classList.value = "badge rounded-pill text-bg-light";
labelElement.style.marginTop = "2rem";

const classifName = document.createElement("span");
classifName.style.marginLeft = "0.5rem";

const classifColor = document.createElement("span");
classifColor.classList.value = "badge rounded-pill";
classifColor.style.color = "white";
classifColor.style.background = "red";
classifColor.style.width = "1rem";
classifColor.innerText = " ";

labelElement.appendChild(classifColor);
labelElement.appendChild(classifName);

const label = new CSS2DObject(labelElement);

instance.add(label);

// Let's query the classification of the picked point and display it in the label.
function updateLabel(mouseEvent) {
  const results = instance.pickObjectsAt(mouseEvent, { radius: 6 });

  // Reset label visibility
  label.visible = false;

  if (results && results.length > 0) {
    for (const result of results) {
      const { object, point, index } = result;

      const classificationIndex = object.getClassification(index);

      const classification = material.classifications[classificationIndex];

      // Let's ignore hidden classifications
      if (classification && classification.visible) {
        const color = classification.color.getHexString();
        classifColor.style.background = `#${color}`;

        classifName.innerText = classificationNames[classificationIndex];

        label.visible = true;
        label.position.copy(point);
        label.updateMatrixWorld(true);

        break;
      }
    }
  }

  instance.notifyChange();
}

bindSlider("pointSize", (v) => {
  material.size = v;
  instance.notifyChange(pointcloud);
});

bindToggle("postProcessingEffects", (v) => {
  instance.renderingOptions.enableEDL = v;
  instance.renderingOptions.enableInpainting = v;
  instance.renderingOptions.enablePointCloudOcclusion = v;
  instance.notifyChange(pointcloud);
});

instance.domElement.addEventListener("mousemove", updateLabel);

Inspector.attach("inspector", instance);
index.html
<!doctype html>
<html lang="en">
  <head>
    <title>Point cloud classification</title>
    <meta charset="UTF-8" />
    <meta name="name" content="point_cloud_classification" />
    <meta name="description" content="Display a classified point cloud." />
    <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/next/css/example.css"
    />

    <style>
      #view canvas {
        background: rgb(132, 170, 182);
        background: radial-gradient(
          circle,
          rgba(132, 170, 182, 1) 0%,
          rgba(37, 44, 48, 1) 100%
        );
      }
    </style>
  </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>

    <div class="side-pane-with-status-bar" style="width: 21rem">
      <div class="mh-100 overflow-y-auto">
        <div class="card mb-1">
          <div class="card-header">Options</div>

          <div class="card-body">
            <fieldset>
              <!-- Point size -->
              <div class="input-group mb-2">
                <label for="pointSize" class="form-label">Point size</label>
                <input
                  type="range"
                  min="0"
                  max="10"
                  value="0"
                  class="form-range"
                  id="pointSize"
                  autocomplete="off"
                />
              </div>

              <!-- Enable point cloud effects -->
              <div class="form-check form-switch">
                <input
                  class="form-check-input"
                  type="checkbox"
                  checked="true"
                  role="switch"
                  id="postProcessingEffects"
                  autocomplete="off"
                />
                <label class="form-check-label" for="postProcessingEffects"
                  >Post-processing effects</label
                >
              </div>
            </fieldset>
          </div>
        </div>

        <div class="card mb-1">
          <div class="card-header">Classifications</div>

          <div class="card-body">
            <fieldset id="classifications">
              <!-- Classifications are added dynamically from the JS example -->
            </fieldset>
          </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>
package.json
{
    "name": "point_cloud_classification",
    "dependencies": {
        "@giro3d/giro3d": "git+https://gitlab.com/giro3d/giro3d.git"
    },
    "devDependencies": {
        "vite": "^3.2.3"
    },
    "scripts": {
        "start": "vite",
        "build": "vite build"
    }
}