🌟 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.
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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.
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Do not set the Town Filter Threshold parameter too high, as it may cause town data fetching to fail.
- 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.
- Standard OpenTTD Tile Presets: Supports official tile resolutions ranging from
64x64up to1048576. - 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 theCtrlkey and drag the box to reposition the selection area seamlessly across the globe.
- 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.
- 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
cityFlag Assignment: Automatically tags major urban areas withcity: truebased on place hierarchy.
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Real-time Canvas Preview: View the grayscale heightmap on an integrated preview canvas before downloading.
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Multiple Town JSON Formats:
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OpenTTD / RoadTycoon Official Spec: Normalized ratio coordinates (0.0–1.0) with swapped X/Y axes and
cityboolean flag. -
Standard GameScript (GS): Absolute tile integer coordinates (
x,y) with scaled population. -
Minimal Ratio Mode: Clean ratio coordinates with town names only.
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One-Click ZIP Packaging: Powered by JSZip, export both the PNG heightmap and Towns JSON together into a single downloadable ZIP file.
- 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.
- Frontend: HTML5, CSS3 (Custom Variables, Backdrop Blur Filters), Pure JavaScript (ES6+)
- Map Engine: Leaflet.js (CartoDB Dark Tiles & OpenStreetMap Light Tiles)
- DEM Data Source: Amazon S3 Terrarium Elevation Tiles
- GIS API: OpenStreetMap Overpass API
- Archiving: JSZip
- Bunburya's script: Bunburya's OpenTTD Heightmap Generator
- Determines the elevation altitude below which pixels are recognized as sea/water in the heightmap.
0m(default), fine-tune based on shorelines.
- Maps the highest real-world mountain peak in your selection to OpenTTD's maximum height steps (default is 2000m).
- Applies a smoothing algorithm to raw elevation tiles to soften jagged noise and sheer cliffs.(default is 2x).
- 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).
- Ensures all land tiles near the coastline maintain a distinct minimum height step above water to avoid rendering artifacts.
- 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)
- Multiplies real-world OpenStreetMap population figures by the specified scale factor to convert them into balanced starting populations for OpenTTD.
- Calculation Formula:
- Examples:
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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$50$ .
- 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.