mesh-dem-to-terrain 🚀🥾

A Node.js library for converting DEM meshes (DXF, GeoJSON, etc.) into Cesium Terrain Tiles (quantized-mesh or heightmap), with flexible zoom-level control.

Table of Contents

* Features
* Installation
* Usage
* API
* Options Overview
* CLI Wrapper Example
* Contributing

🎉 Features

* 🔄 Preprocess Mesh Archive: Unpacks and prepares DXF/GeoJSON mesh archives into a working directory, reprojects coordinates using Proj4 strings. 🗺️
* 🗻 Terrain Tile Generation: Generates Cesium-compatible terrain tiles (quantized-mesh or heightmap) across specified zoom levels. 📈
* 📐 Projection Support: Accept any Proj4-formatted CRS string for flexible coordinate transformations. ✨
* 📊 Progress Callbacks: Receive real-time progress updates (percentage or log messages). 📢
* 🧵 Multi-threading: Customize worker threads for CPU-bound tasks. ⚙️

📥 Installation

``bash
npm install mesh-dem-to-terrain
`

💻 Usage

`js
import { preprocess, generate } from "mesh-dem-to-terrain/index.js";

(async () => {
// Step 1: Unpack and reproject your mesh archive 🛠️
await preprocess(
"D:\\dxf.zip", // Path to DXF/GeoJSON archive
"D:\\dxf_test", // Working directory for intermediate files
console.log, // Progress callback (log messages)
"+proj=utm +zone=32 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs +type=crs" // Proj4 CRS string
);

// Step 2: Generate Cesium Terrain Tiles 🌄
await generate(
"D:\\dxf_test", // Working directory from preprocess
(progress) => console.log((progress * 100).toFixed(2), "%"), // Progress callback (percentage)
{ endZoom: 16, startZoom: 0, threadCount: 2 } // Options: zoom range & threads
);
})();
`

⚙️ API

$3

* inputArchive (string) – Path to a ZIP archive containing DXF, GeoJSON, or other mesh files. 📂
* workDir (string) – Directory to extract and preprocess mesh data. 📁
* progressCallback (function) – Called with log messages or progress updates. 📢
* proj4String (string) – Proj4-formatted CRS string for coordinate transformation. 🌍

Returns: A promise that resolves when preprocessing is complete. ✅

$3

* workDir (string) – Directory prepared by preprocess(). 📂
* progressCallback (function) – Called with a number in \[0,1] indicating progress. 📈
* options (object):

* startZoom (number) – Minimum zoom level to generate (default: 0). ↗️
* endZoom (number) – Maximum zoom level to generate (required). ↘️
* threadCount (number) – Number of worker threads (default: number of CPU cores). 🧵

Returns: A promise that resolves when terrain tile generation is complete. ✅

🛠️ Options Overview

| Option | Default | Description |
| ------------- | ------------------ | ------------------------------------------ |
| startZoom | 0 | Minimum zoom level for generated tiles. ↗️ |
| endZoom | required | Maximum zoom level for generated tiles. ↘️ |
| threadCount | os.cpus().length | Number of parallel worker threads. 🧵 |

📜 CLI Wrapper Example

Wrap the library in a convenient CLI script:

`js
#!/usr/bin/env node
import path from "path";
import { preprocess, generate } from "mesh-dem-to-terrain/index.js";

const [,, archive, outDir, proj, startZ, endZ, threads] = process.argv;

(async () => {
// Preprocess mesh archive 🛠️
await preprocess(
path.resolve(archive),
path.resolve(outDir),
console.log,
proj
);

// Generate terrain tiles 🌄
await generate(
path.resolve(outDir),
(p) => console.log(${(p*100).toFixed(2)} %),
{
startZoom: Number(startZ) || 0,
endZoom: Number(endZ) || 16,
threadCount: Number(threads) || 4
}
);
})();
``

🤝 Contributing

Contributions are welcome! Please open issues or pull requests on the GitHub repository. 🙌