Sphere Web

Web Map to Equirectangular Projection System for Harvard Science Sphere Display

A browser-native system to display live geospatial web maps on spherical projection surfaces. The system captures web maps (Leaflet, OpenLayers, MapLibre), detects their projection, and transforms them in real-time to equirectangular format using WebGL fragment shaders.

## Two Complementary Approaches **OBS/MadMapper Workflow:** - Mixed media sphere content - Live presentations and VJ events - Multi-source composition - Full control during performances **Browser-Native WebGL:** - Automated 24/7 operation - Map-focused content - Unattended installations - Direct web integration

## Interactive Capabilities - **Presence detection**: Browser computer vision detects people approaching - **Mobile browser control**: Visitors control sphere from phones - **User-submitted URLs**: Visitors load URLs during their visit - **Class playlists**: Students load custom playlists for presentations - **Dwell-time adaptation**: Content pacing based on how long people stay

## Architecture ``` Chrome Extension loads target URL ↓ Content script detects & manipulates map ↓ WebGL context captures map viewport ↓ Fragment Shader transforms projection ↓ Output canvas renders equirectangular ↓ MadMapper → Science Sphere ```

## Projection Transform Web Mercator to Equirectangular via GLSL fragment shader: - Convert latitude to Web Mercator Y - Longitude passes through (both cylindrical) - Clamp to valid Mercator range (~85°) - Black fill outside bounds

## Target Installations Harvard Science Spheres at: - Cabot Library - Natural History Museum - Graduate School of Design