Select an area to compute wall orientations & infer historical magnetic declination
RISWMP · Vosburgh 2025Draw a box or choose a town, then click Analyze
The rose diagram will show how wall segments are oriented relative to true north
The RIGIS ArcGIS server blocks direct browser requests (CORS policy). Instead, download the GeoJSON yourself and drop it here:
The file stays local — nothing is uploaded anywhere.
Download the municipalities GeoJSON from rigis.org (Download → GeoJSON), then drop it here:
If the dominant bearing reflects a survey grid, the angular offset from a cardinal direction suggests the compass declination at time of survey.