Simutrans CityView (English)

These are slides presented at the Simutrans Idobata Meetup 2026 (January 24, 2026).

I've created a service called Simutrans CityView. The demo site is available at https://cityview.sou7.io .

Transcript

1. Simutrans CityView Simutrans Idobata Meetup 2026 2026-01-24 1
2. About Me I’m sou7 Simutrans experience: Playing since around when gradient slopes were introduced Favorite versions: Extended, OTRP Favorite paksets: Pak128.Britain-Ex Pak128.Japan 2
3. Contact ActivityPub/Misskey: @sou7@mi.sou7.io → Twitter: @sou7_ _ _ GitHub: @soukouki 3
4. Demo Site https://cityview.sou7.io/ 4
5. Why I Created CityView Have you ever wanted to show off or share your maps with others? Traditional Methods Post screenshots on social media You can only show a small portion Write a development blog Time-consuming to write Upload videos Even more time-consuming to produce Distribute save files High barrier to entry for people to download and run 5
6. The Challenge of Map Viewing in Multiplayer Some multiplayer servers accept visitors for map viewing, but there’s still a high barrier to entry: 1. Find a Discord invite link 2. Join a Discord server full of strangers 3. Download the client and pakset When I opened my own multiplayer server and accepted visitors, it seemed like no one actually got to the point of running it locally. 6
7. Previous Approaches Himeshi developed a system using Docker to run a VNC server that you could connect to via noVNC from a browser[1]. However, this approach has some problems: Significant input lag Terrible compatibility with right-drag camera movement These issues severely impact the user experience. I also tried other VNC clients and remote desktop software like RustDesk, but ran into the same problems. 7
8. CityView Features Users can explore maps simply by opening a website in their browser Smooth, responsive controls thanks to web mapping libraries Low server load during access since map tiles are pre-generated The tradeoff: tile generation is quite heavy and time-consuming Can host multiple maps Switch between different time periods of the same map Watch how locations develop over time! Supports Standard, Extended, and OTRP 8
9. How CityView Works Launch Simutrans in a Docker container and capture screenshots Screenshot positions have significant error, so alignment is needed Cut into square tiles for the map rendering library※ ※In practice, tiles are also combined to generate lower zoom level images and compressed. 9
10. Want to Try CityView? Would you like to publish your local development maps or multiplayer server maps with CityView? 10
11. Required Hardware Linux is recommended. In theory, any OS that runs Docker should work, but tile generation (which is already heavy) will be even slower on other systems. Memory requirements depend on settings, but I think 8GB minimum will work. 16GB is better, 32GB gives peace of mind. CPU-intensive processing, so more cores is better. Even with a 6-core 12- thread machine, capturing the Kumagaya map (1280x640) at 1x zoom took about 40 minutes. SSD recommended. 11
12. Setup Instructions 1. Install Docker, Docker Compose, and Git 2. Run git clone https://github.com/soukouki/CityView.git 3. Copy .env.sample to .env and edit the settings You can specify parallelism level, so adjust according to your CPU performance 4. Run sudo docker compose up -d --build 5. Access these screens: http://localhost:8000 : Map viewing interface http://localhost:8001 : Admin interface http://localhost:4200 : Prefect dashboard For monitoring map generation progress 12
13. 6. Place your Simutrans installation in the volume-bin folder Place Linux executable files and don’t forget to set permissions with chmod u+x <executable> The system searches intelligently under volume-bin , so subfolders are OK 7. Add a map through the admin interface 8. Wait a few minutes to several hours for map generation to complete, monitoring progress in the Prefect dashboard Runs tab 9. Once it shows Completed , your map will be viewable in the map interface 13
14. Future Plans Real-time Updates I want to set up a client connected to a multiplayer server and generate/view real-time map tiles at around 1 frame per second when zoomed in. Underground Display Capture in underground display mode too, so you can see subways and other underground features. 14
15. Label Search Use OCR to detect labels like station names, city names, and train route displays, making them searchable and useful in other ways. However, OCR doesn’t work well on raw screenshots, so I’ll need techniques like extracting just the label portions before running OCR. Auto-generate Map Highlights Use VLM technology (the currently popular AI/LLM image recognition tech) to automatically detect and generate interesting points on the map. 15
16. Summary Developed Simutrans CityView, a system for exploring maps in a browser Achieved smooth user experience by pre-generating map tiles Runs in Docker containers, making it relatively easy to set up Future plans include real-time updates and auto-generated highlights Demo site: https://cityview.sou7.io/ 16
17. Bonus Lines of code: Exactly 6000 lines Language Lines Python 2635 lines Ruby 1949 lines HTML 1416 lines I like Ruby, so I wrote parts that could be done in Ruby using Ruby. Category Lines prefect 1573 lines service-capture 968 lines service-* (others) 1062 lines Backend 981 lines Frontend 1416 lines 17
18. References 1. DockerでSimutransオンライン #Docker - Qiita 18