k-forge blogNotes from building walker: GPS, offline maps, batteries and your data, and the maths behind it.https://k-forge.dev/blog/feed.xml2026-09-28T00:00:00ZMalikOffline map of Tyrol for hiking: districts and sizeshttps://k-forge.dev/blog/offline-map-of-tyrol2026-09-28T00:00:00Z2026-09-28T00:00:00ZTyrol's nine districts measured: how big each map and its terrain are to download, which ones a trip from Innsbruck needs, and how to test them offline.Record a hike with your phone: what the recording needshttps://k-forge.dev/blog/record-a-hike-with-your-phone2026-09-28T00:00:00Z2026-09-28T00:00:00ZLocation, battery, an offline map and free space: set up once, try it on a short test walk, then check the track and keep a copy of it.TopPlusOpen and aerial photos offline: official mapshttps://k-forge.dev/blog/official-topographic-maps-offline2026-09-28T00:00:00Z2026-09-28T00:00:00ZWhat Germany's official topographic map and the states' aerial photos show, what their open licences allow, the credit they ask for, and where they stop.An app with no serverhttps://k-forge.dev/blog/an-app-with-no-server2026-09-27T00:00:00Z2026-09-28T00:00:00Zwalker has no server, no account and no sync. How it keeps everything on the phone, how its encrypted backups work, and what that costs.Cleaning GPS tracks with a factor graph on a phonehttps://k-forge.dev/blog/cleaning-gps-tracks-with-a-factor-graph2026-09-27T00:00:00Z2026-09-28T00:00:00ZHow walker cleans GPS tracks on the phone: a hand-rolled factor graph with steps, the barometer and raw satellites, and what it measured.Hiking with offline maps on Androidhttps://k-forge.dev/blog/offline-maps-for-hiking-on-android2026-09-27T00:00:00Z2026-09-28T00:00:00ZWhy your hiking map should work without signal, how to download and test it before you go, and what an offline map can and can't do.Making contour lines and hillshading on the phonehttps://k-forge.dev/blog/contour-lines-and-hillshading-on-the-phone2026-09-27T00:00:00Z2026-09-28T00:00:00ZHow walker turns open lidar terrain into hillshading and contour lines on an Android phone: Horn's method, marching squares, Douglas–Peucker and MVT.Own your walks: GPX export and backupshttps://k-forge.dev/blog/own-your-walks-gpx-and-backups2026-09-27T00:00:00Z2026-09-28T00:00:00ZWhat a GPX file is, how to get your walks out of Strava, Komoot or Garmin Connect, and how to keep a backup that outlives any app or phone.Using every satellite your phone measureshttps://k-forge.dev/blog/every-satellite-your-phone-measures2026-09-27T00:00:00Z2026-09-28T00:00:00ZHow walker uses Android's raw GNSS measurements from five satellite systems and two bands on the phone, and what it gained on a real ride.What your walking app knows about youhttps://k-forge.dev/blog/what-your-walking-app-knows2026-09-27T00:00:00Z2026-09-28T00:00:00ZA walk track shows where you live and when you are out. Real cases of fitness data exposing people, and the settings that keep your home private in any app.When Android stops your tracker in the backgroundhttps://k-forge.dev/blog/when-android-stops-your-tracker2026-09-27T00:00:00Z2026-09-28T00:00:00ZKeep your hike's track whole: why Android stops a recording in the background, which phone settings prevent it, and how to tell when it happened.Why every app shows a different elevation gainhttps://k-forge.dev/blog/why-elevation-gain-differs2026-09-27T00:00:00Z2026-09-28T00:00:00ZSame hike, three different climbs. Why GPS height, the barometer, terrain maps and sea level all disagree, and which figure to trust.Why your GPS track is longer than the walk you tookhttps://k-forge.dev/blog/gps-track-longer-than-the-walk2026-09-27T00:00:00Z2026-09-28T00:00:00ZGPS noise makes almost every recorded walk too long. Why that happens, why two apps disagree, and how cleaning a track takes the extra out.Writing a whole Android app in Rusthttps://k-forge.dev/blog/android-app-in-rust2026-09-27T00:00:00Z2026-09-28T00:00:00Zwalker is an Android app written in Rust: egui on wgpu, offline vector maps, an embedded SurrealDB and a little Java. What worked and what hurt.