OpenTTD-Heightmap-Generator

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OpenTTD-Heightmap-Generator

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OpenTTD Heightmap Generator is a modern, high-precision web tool designed to generate realistic 8-bit heightmaps and extract real-world town data for OpenTTD.

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- - openttd_heightmap_4096x4096_fuji.png
  - openttd_heightmap_4096x8192_North_Japan.png
  - openttd_heightmap_8192x8192_Hokkaido.png
  - openttd_heightmap_8192x8192_ky.png
  - openttd_heightmap_8192x8192_osaka.png
  - openttd_towns_4096x4096_fuji.json
  - openttd_towns_4096x8192_North_Japan.json
  - openttd_towns_8192x8192_hokkaido.json
  - openttd_towns_8192x8192_ky.json
  - openttd_towns_8192x8192_osaka.json
  - shikoku_8192.zip
- OpenTTD-Heightmap-Generator.html
- OpenTTD-Heightmap-Generator_8192.html
- OpenTTD-Heightmap-Generator_8192_fix_rotate.html
LICENSE
OpenTTD-Heightmap-Generator_8192_fix.html
OpenTTD-Heightmap-Generator_8192_fix_11.html
OpenTTD-Heightmap-Generator_8192_fix_7.html
README.md

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🌟 Project Overview
OpenTTD Heightmap Generator is a modern, high-precision web tool designed to generate realistic 8-bit heightmaps and extract real-world town data for OpenTTD.Powered by OpenStreetMap (OSM) vector data and Terrarium DEM global elevation tiles, it enables players to select any geographic region on Earth, fine-tune terrain smoothing and water levels, and export game-ready PNG heightmaps along with structured JSON town configurations in one click.

### Try Out: https://zyliety.github.io/OpenTTD-Heightmap-Generator.html

### Note:

* Do not select an area that is too large. It is recommended to keep both the length and width under 8192 pixels, otherwise the export speed will be significantly affected.

* Do not set the Town Filter Threshold parameter too high, as it may cause town data fetching to fail.

### ✨ Key Features & Highlights

#### 1. 🍎 Friendly UI & Dual Theme System

* **Day / Night Mode Switch**: Starts in Light Mode by default. Effortlessly switch to Dark Mode via the top-right toolbar button.
* **Fixed Top-Right Control Bar**: Theme toggle and language selection are fixed at the top-right corner to ensure uncluttered map interactions.

#### 2. 📐 Fixed Aspect-Ratio Region Selection

* **Standard OpenTTD Tile Presets**: Supports official tile resolutions ranging from `64x64` up to `1048576`.
* **Locked Aspect Ratio Box**: The selection box automatically locks its proportions to match the selected map dimensions, preventing geographic distortion.
* **Shortcut Drag-to-Move (`Ctrl + Drag`)**: Hold the `Ctrl` key and drag the box to reposition the selection area seamlessly across the globe.

#### 3. 🏔️ DEM Elevation Processing & Terrain Smoothing

* **Bilinear Interpolation Sampling**: Smoothly resamples elevation tiles to prevent pixelation artifacts in scaled maps.
* **Precision Sea Level & Altitude Mapping**: Customize sea level cutoffs and maximum mountain elevations.
* **Multi-pass Box Filter Smoothing**: Flatten jagged mountain cliffs into gentler slopes that are ideal for building railway networks and roads.
* **Inland Lake Detection & Infill**: Built-in flood-fill algorithm automatically detects inland basins below sea level and fills them to prevent unnatural dry craters.
* **Custom Low-Elevation Offset**: Option to forcibly raise coastal or sub-sea-level land to specified target elevations.

#### 4. 🏙️ Real-World OSM Town Data Extraction

* **Live Overpass API Queries**: Fetches cities, towns, villages, and suburbs with their real-world names, coordinates, and populations within the box.
* **Multi-Mirror Endpoint Failover**: Automatically cascades across multiple Overpass API mirrors (`Overpass-API`, `Kumi`, `Mail.ru`) to ensure maximum reliability.
* **Population Scaling & Filter Thresholds**: Adjust population scale factors and filter towns based on OSM place ranks to control map node density.
* **Smart `city` Flag Assignment**: Automatically tags major urban areas with `city: true` based on place hierarchy.

#### 5. 📦 Multiple Export Formats & One-Click ZIP Packaging

* **Real-time Canvas Preview**: View the grayscale heightmap on an integrated preview canvas before downloading.
* **Multiple Town JSON Formats**:
* **OpenTTD / RoadTycoon Official Spec**: Normalized ratio coordinates (0.0–1.0) with swapped X/Y axes and `city` boolean flag.
* **Standard GameScript (GS)**: Absolute tile integer coordinates (`x`, `y`) with scaled population.
* **Minimal Ratio Mode**: Clean ratio coordinates with town names only.

* **One-Click ZIP Packaging**: Powered by JSZip, export both the PNG heightmap and Towns JSON together into a single downloadable ZIP file.

#### 6. 🌐 Intuitive Interaction & Multi-language Support (i18n & Tooltips)

* **Native i18n**: Seamless switching between **English (EN)**, **Chinese (ZH)**, and **Japanese (JA)**.
* **Hover Parameter Documentation**: Hovering over any parameter section displays an interactive tooltip explaining its usage based on OpenTTD specifications.
* **One-Click Reset Button**: Easily revert all sliders, checkboxes, and selections back to default baseline values.

---

### 🛠️ Tech Stack

* **Frontend**: HTML5, CSS3 (Custom Variables, Backdrop Blur Filters), Pure JavaScript (ES6+)
* **Map Engine**: [Leaflet.js](https://www.google.com/search?q=https://leafletjs.com/) (CartoDB Dark Tiles & OpenStreetMap Light Tiles)
* **DEM Data Source**: Amazon S3 Terrarium Elevation Tiles
* **GIS API**: OpenStreetMap Overpass API
* **Archiving**: [JSZip](https://www.google.com/search?q=https://stuk.github.io/jszip/)
* **Bunburya's script**: Bunburya's OpenTTD Heightmap Generator

### 🔰 Parameter Beginner's Guide

#### 1. Water Level Cutoff

* Determines the elevation altitude below which pixels are recognized as sea/water in the heightmap. `0m` (default), fine-tune based on shorelines.

#### 2. Max Elevation

*  Maps the highest real-world mountain peak in your selection to OpenTTD's maximum height steps (default is 2000m).

#### 3. Terrain Smoothing (Box Filtering)

*  Applies a smoothing algorithm to raw elevation tiles to soften jagged noise and sheer cliffs.(default is 2x).

#### 4. Force Lift Sea Level & Below Pixels

*  Forcibly elevates land areas that are at or below sea level by a specified offset, preventing them from being submerged. **Checked** when mapping low-lying coastal regions (e.g., Netherlands, Venice).

#### 5. Force Lift Low-Elevation Land

*  Ensures all land tiles near the coastline maintain a distinct minimum height step above water to avoid rendering artifacts.

#### 6. Inland Lake Detection & Infill

* Uses a flood-fill algorithm to separate ocean coastal water from inland below-sea-level basins, automatically filling dry interior depressions.

(You could check them on https://github.com/bunburya/bother)

#### 7. Population Scale

*  Multiplies real-world OpenStreetMap population figures by the specified scale factor to convert them into balanced starting populations for OpenTTD.
* **Calculation Formula**:

$$\text{In-Game Population} = \text{Real OSM Population} \times \text{Population Scale}$$

* **Examples**:
* **Example 1 (Scale = `0.01` / 1%)**: Real metropolis with **1,000,000** residents becomes $1,000,000 \times 0.01 = 10,000$ in-game population; town of **50,000** becomes $500$.
* **Example 2 (Scale = `0.05` / 5%)**: A city with **1,000,000** residents yields $50,000$ in-game population.
* **Example 3 (Scale = `0.001` / 0.1%)**: A city of **1,000,000** becomes $1,000$ residents; town of **50,000** shrinks to $50$.

#### 8. Town Filtering Threshold

*  Filters out small settlements or low-priority nodes based on population size or administrative rank to prevent map clutter.
* **Threshold Values (`0`, `0.5`, `1`)**:
* **Set to `1` (Keep All)**: Retains 100% of OSM nodes in the selection (including small villages, tiny hamlets, and farmsteads).
* **Set to `0.5` (Balanced Clean-up)**: Automatically purges minor hamlets, keeping medium-to-large towns and main cities intact.
* **Set to `0` ( Major Cities Only)**: Strips away almost all minor towns to keep only top-tier urban centers.

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