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David – Cold Cities Warm Stories

2nd place in the City of Munich challenge at hackaTUM 2022: an iOS app that turns the city into a map of pinned stories, with ML genre tagging, upvotes and badges.

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Context

Every street in Munich has stories nobody has written down. At hackaTUM 2022, TUM's annual hackathon, Heidi and her teammates Bethany Wong, Akshar Singh and Hannes Wagner set out to make them visible, and took 2nd place in the City of Munich challenge.

Tagline: Write stories about your favourite places in town — see your city with new eyes.

Inspiration

Local tourist guides, museum audio guides, location-based games and the community sticky notes you find pinned up in coffee shops.

What we built

An iOS app that uses gamification to make people's experience of Munich warmer and more personal:

  • While walking through the city, users pin a story to a building as a digital sticky note on a map.
  • A machine-learning model classifies each story into a genre (bag-of-words NLP pipeline).
  • Users read others' stories by theme and upvote or downvote them.
  • A leaderboard ranks the top stories, and users earn badges based on how many stories they've written.
  • Goals: get people outside exploring, build a shared space for ideas, offer interest-based travel spots, and give writers live feedback from readers.

Tech

Swift (iOS app + UI, maps and location) · Java (HTTP backend server built from scratch) · Python (NLP preprocessing) · bag-of-words text classifier · JSON

Challenges and learnings

  • Integrating parts written in different languages across platforms, and connecting the app to the server/database.
  • Learned to build a bag-of-words pipeline, use device location on a map, and write an HTTP server from scratch.

What's next (from the team's plan)

Show notes within a radius of your location, ML recommendations of notes, and AR to scan buildings and read notes attached to them — with video and music so you feel you're living through someone's story.

Result

🥈 2nd place — City of Munich challenge, hackaTUM 2022 (November 2022).

Links