Umbra Sphere

Umbra Sphere is a proof-of-concept app, we use a geospatial technology called "S²Geometry" to store the locations you've visited, identify which country or region they belong to and present them on a map as cleared shadows (umbra). S²Geometry is a geocoding system that divides the Earth's surface into "cells" ranging from 85 million square kilometers to 0.5 square centimeters. These cells are converted into 64-bit integers using the Hilbert curve. Compared with traditional latitude-longitude coordinate system and map projections, S²Geometry is less intuitive, but it avoids significant distortion, delivers globally consistent accuracy, and offers extraordinary indexing and querying performance. With these advantages, Umbra Sphere converts traces into a series integers and stores them in database with appropriate indexes to generate umbra fast in real-time for displaying. It also provides statistical features, presenting the areas of countries or regions you've visited on "visa" cards. Additionally, Umbra Sphere also features a simple S²Geometry visualization tool, allowing you to view S²Geometry cells and their corresponding integer IDs directly on the map. ● Umbra Sphere supports importing these file types: • GPX and KML trace files • Sync files and snapshot files from Fog of World • Backup CSV files from StepLife ● Privacy We respect privacy, and simply do not collect any of your data. All your data are stored in your device. Umbra Sphere does not provide sync feature, you can manually export and import your data.