LiDAR fun

index.js

"use strict";

const vtpbf = require('vt-pbf');
const fs = require('fs');
const geojsonVt = require('geojson-vt');
const SphericalMercator = require('@mapbox/sphericalmercator');
const util = require('util');
const cp = require('child_process');
const PromisePool = require('es6-promise-pool')

function execute_pdal(options, callback) {
    var merc = new SphericalMercator({
        size: 4096
    });
    var bbox = merc.bbox(options.x, options.y, options.zoom, false, "900913");
    var bounds = "([" + bbox[0] + "," + bbox[2] + "],[" + bbox[1] + "," + bbox[3] + "])";
    var width = (Math.abs(bbox[2] - bbox[0]) / options.extent) * 16;
    var pdal_obj = {
        "pipeline": [
            options.input_file,
            {
              "type":"filters.crop",
              "bounds": bounds
            },
            {
              "type":"filters.voxelcentroidnearestneighbor",
              "cell": width
            },
            {
              "type":"filters.reprojection",
              "in_srs":"EPSG:3857",
              "out_srs":"EPSG:4326"
            },
            {
              "type":"writers.text",
              "format":"geojson",
              "order":"Red:0,Green:0,Blue:0",
              "precision": 6,
              "keep_unspecified":"false",
              "filename": "STDOUT"
            }

        ]
    };
    let tmp_pipeline_file = 'tmp/pdal_config_' + options.zoom + '_' + options.x + '_' + options.y + '.json'
    fs.writeFile(tmp_pipeline_file, JSON.stringify(pdal_obj), (err) => {
        if (err) throw err;
        cp.exec('pdal pipeline ' + tmp_pipeline_file, {maxBuffer: 1024 * 1024 * 1024}, callback);
    });
}

const create_tile = (options, callback) => {
    console.log('Creating tile: ' + options.zoom + ',' + options.x + ',' + options.y)
    execute_pdal(options, (err, stdout, stderr) => {
        if (err) {
            console.log(err);
            console.log(stderr);
        }
        try {
            var orig = JSON.parse(stdout);
            var tileindex = geojsonVt(orig, {
                buffer: 0, 
                dimensions: 3, 
                maxZoom: 19});
            var tile = tileindex.getTile(options.zoom, options.x, options.y);
            if (!tile) {
                console.log("no data to tile");
                callback();
            }
            var buff = vtpbf.fromGeojsonVt({ 'geojsonLayer': tile });
            fs.writeFile('tiles/'+ options.zoom + '_' + options.x + '_' + options.y + '.mvt', buff, callback);
        } catch (error) {
            console.log(error);
            callback();
        }
    });
}

const tile_promise = util.promisify(create_tile);

const generateTilePromises = function * () {
    let start_z = 16;
    let end_z = 16;
    // start and end in start_z coordinates
    let start_x = 18740;
    let end_x = 18748;
    let start_y = 25071;
    let end_y = 25073;

    for (let z = start_z; z <= end_z; z++) {
        let s_x = start_x * (1 << (z - start_z));
        let e_x = (end_x + 1) * (1 << (z - start_z));
        let s_y = start_y * (1 << (z - start_z));
        let e_y = (end_y + 1) * (1 << (z - start_z));
        for (let x = s_x; x < e_x; x++) {
            for (let y = s_y; y < e_y; y++) {
                yield tile_promise({
                    zoom: z,
                    x: x,
                    y: y,
                    extent: 4096,
                    input_file: "color.las"
                });
            }
        }
    }
}
 
const concurrency = 2;
const promiseTileIterator = generateTilePromises();

// Create a pool.
var pool = new PromisePool(promiseTileIterator, concurrency);

// Start the pool.
var poolPromise = pool.start();

// Wait for the pool to settle.
poolPromise.then(function () {
  console.log('All promises fulfilled')
}, function (error) {
  console.log('Some promise rejected: ' + error.message)
});

package.json

{
  "name": "mypoints",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "dependencies": {
    "@mapbox/point-geometry": "https://github.com/mapbox/point-geometry/tarball/3d",
    "@mapbox/vector-tile": "https://github.com/mapbox/vector-tile-js/tarball/vt3-3d",
    "geojson-vt": "https://github.com/mapbox/geojson-vt/tarball/3d",
    "vt-pbf": "https://github.com/mapbox/vt-pbf/tarball/vt3-3d",
    "@mapbox/sphericalmercator": "^1.0.5",
    "es6-promise-pool": "2.5.0"
  },
  "devDependencies": {},
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC"
}