Showing posts from August, 2020

Building a 3D Model of the Beirut Explosion

Blast damage assessment in Beirut is being carried out using two-dimensional satellite imagery. These approaches underestimate damage by failing to capture damage done to the sides of buildings. I outline an alternative approach using Open Street Map data to create a 3D model of Beirut and the explosion to analyze directional blast damage.  Satellite Imagery and its Limits Following the recent explosion in Beirut, I built a tool that uses Sentinel-2 imagery to map the destruction caused by the blast. After some trial and error, I arrived at a fairly simple two step process: first, measuring the change in spectral signatures between pre- and post-explosion images. Second, applying an X-Means clustering algorirthm to the resulting image (yielding the map on the right), or taking the absolute difference (yielding the map on the left): Red areas on the left indicate high levels change between the pre- and post- explosion images. On the right, the magnitude, direction, and spectral