I’m Jinho — I built a 267K-building 3D Seoul with GPT-6 Astra, and it reached 330K+ views on X

Hi Product Hunt 👋

I’m Jinho, an Codex hands-on builder based in Seoul, South Korea. My background spans AI infrastructure, GPU Data Center computing, LLM training and inference, Kubernetes, and enterprise AI systems. These days, I’m especially interested in one question:

What happens when AI stops being just a coding assistant and becomes part of the entire product-building process?

That question led me to build Seoul 3D Atlas - Seoul on Miniature.

It started as a small experiment: could I turn Seoul into an interactive 3D city that people could actually explore?

The first version was simply about seeing Seoul in 3D. Then I started using it myself. Once the city existed, I wanted to know how people moved through it, so I added subway routes. Then buses.

Transportation led to landmarks, hotels, cultural sites, hiking trails, and tourism information.

As the experience grew, I added multilingual UI, multiple currencies, weather, seasons, day/night modes, mobile interactions, and more.

Today, Seoul 3D Atlas brings together 267,000+ buildings and multiple layers of city data in one interactive 3D experience. But the part I find most interesting is how it was built.

I developed it through repeated iterations with GPT-6 Astra and Codex.

Not:

prompt → code → done

but more like:

idea → implementation → test → problem → debugging → new requirement → iteration → repeat

I made the product decisions, tested the experience, identified what felt wrong or was missing, and kept directing the next iteration while Astra and Codex helped turn those decisions into a working product.

The project gradually became an experiment in human + AI software development, not just AI-generated code. Then something unexpected happened. I shared a demo on X, and it reached 330K+ views.

Seeing that response made me realize that people weren't only interested in the technology — they were interested in a different way of experiencing a real city.

So now I’m bringing the project to Product Hunt. I’m here not only to launch Seoul 3D Atlas, but also to meet other builders experimenting with AI agents, coding agents, interactive experiences, LLM infrastructure, and new ways of building software.

I’d especially love to compare notes with anyone using AI across the entire product lifecycle, rather than just for generating the first prototype.

And I’m curious:

If you had GPT-6 Astra and Codex as part of your development team, what would you build that felt too ambitious to build alone?

Glad to be here. 👋🏙️ https://seoul-3d-atlas-new.synabreu.chatgpt.site/