iTowns / itowns / 11276064531

import proj4 from 'proj4';

import { Binary, Info, Las } from 'copc';

import Extent from 'Core/Geographic/Extent';

import Fetcher from 'Provider/Fetcher';

import LASParser from 'Parser/LASParser';

import Source from 'Source/Source';

import * as THREE from 'three';

/**

 * @param {function(number, number):Promise<Uint8Array>} fetcher

 */

async function getHeaders(fetcher) {

    const header =

        Las.Header.parse(await fetcher(0, Las.Constants.minHeaderLength));

    const vlrs = await Las.Vlr.walk(fetcher, header);

    // info VLR: required by COPC

    const infoVlr = Las.Vlr.find(vlrs, 'copc', 1);

    const info = Info.parse(await Las.Vlr.fetch(fetcher, infoVlr));

    // OGC Coordinate System WKT: required by LAS1.4

    const wktVlr = Las.Vlr.find(vlrs, 'LASF_Projection', 2112);

    const wkt = Binary.toCString(await Las.Vlr.fetch(fetcher, wktVlr));

    // Extra bytes: optional by LAS1.4

    const ebVlr = Las.Vlr.find(vlrs, 'LASF_Spec', 4);

        Las.ExtraBytes.parse(await Las.Vlr.fetch(fetcher, ebVlr)) :

        [];

    return { header, info, wkt, eb };

}

/**

 * A source for [Cloud Optimised Point Cloud](https://copc.io/) (COPC) data.

 * Such data consists of a [LAZ 1.4](https://www.ogc.org/standard/las/) file

 * that stores compressed points data organized in a clustered octree.

 *

 * A freshly created source fetches and parses portions of the file

 * corresponding to the LAS 1.4 header, all the Variable Length Record (VLR)

 * headers as well the following VLRs:

 * - COPC [`info`](https://copc.io/#info-vlr) record (mandatory)

 * - LAS 1.4 `OGC Coordinate System WKT` record (mandatory, see [Las 1.4

 *   spec](https://portal.ogc.org/files/?artifact_id=74523))

 * - LAS 1.4 `Extra Bytes` record (optional, see [Las 1.4

 *   spec](https://portal.ogc.org/files/?artifact_id=74523))

 *

 * @extends {Source}

 *

 * @property {boolean} isCopcSource - Read-only flag to check that a given

 * object is of type CopcSource.

 * @property {Object} header - LAS header of the source.

 * @property {Object[]} eb - List of headers of each Variable Length Records

 * (VLRs).

 * @property {Object} info - COPC `info` VLR.

 * @property {number[]} info.cube - Bounding box of the octree as a 6-elements.

 * tuple `[minX, minY, minZ, maxX, maxY, maxZ]`. Computed from `center_x`,

 * `center_y`, `center_z` and `halfSize` properties.

 * @property {Object} info.rootHierarchyPage - Hierarchy page of the root node.

 * @property {number} info.rootHierarchyPage.pageOffset - Absolute Offset to the

 * root node data chunk.

 * @property {number} info.rootHierarchyPage.pageOffset - Size (in bytes) of the

 * root node data chunk.

 * @property {number[]} gpsTimeRange - A 2-element tuple denoting the minimum

 * and maximum values of attribute `gpsTime`.

 */

class CopcSource extends Source {

    /**

     * @param {Object} config - Source configuration

     * @param {string} config.url - URL of the COPC resource.

     * @param {8 | 16} [config.colorDepth=16] - Encoding of the `color`

     * attribute. Either `8` or `16` bits.

     * @param {string} [config._lazPerfBaseUrl] - (experimental) Overrides base

     * url of the `las-zip.wasm` file of the `laz-perf` library.

     * @param {string} [config.crs='EPSG:4326'] - Native CRS of the COPC

     * ressource. Note that this is not for now inferred from the COPC header.

     * @param {RequestInit} [config.networkOptions] - Fetch options (passed

     * directly to `fetch()`), see [the syntax for more information](

     * https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch#Syntax).

     * @param {Object} [config.attribution] - Attribution of the data.

     */

    constructor(config) {

        super(config);

        this.isCopcSource = true;

        this.parser = LASParser.parseChunk;

        this.fetcher = Fetcher.arrayBuffer;

        this.colorDepth = config.colorDepth ?? 16;

        const get = (/** @type {number} */ begin, /** @type {number} */ end) =>

            this.fetcher(this.url, {

                ...this.networkOptions,

                headers: {

                    ...this.networkOptions.headers,

                    range: `bytes=${begin}-${end - 1}`,

                },

            }).then(buffer => new Uint8Array(buffer));

        this.whenReady = getHeaders(get).then((metadata) => {

            this.header = metadata.header;

            this.info = metadata.info;

            this.eb = metadata.eb;

            proj4.defs('unknown', metadata.wkt);

            let projCS;

            if (proj4.defs('unknown').type === 'COMPD_CS') {

                console.warn('CopcSource: compound coordinate system is not yet supported.');

                projCS = proj4.defs('unknown').PROJCS;

            if (!proj4.defs(this.crs)) {

                proj4.defs(this.crs, projCS);

            }

            const bbox = new THREE.Box3();

            bbox.min.fromArray(this.info.cube, 0);

            bbox.max.fromArray(this.info.cube, 3);

            this.extent = Extent.fromBox3(this.crs, bbox);

            return this;

        });

    }

}

export default CopcSource;