Using Non-authoritative Sources During Emergencies in Urban Areas - Computational Approaches for Urban Environments - page 334

14.2.1.3 Non-authoritative Data

Non-authoritative data are not produced or distributed from necessarily trusted
sources and often lack any assertion of verification or accuracy. However, regard-
less of varying levels of certainty or trustworthiness, non-authoritative sources
can provide valuable, real-time, on-the-ground information during disasters when
traditional sources are unavailable, lacking, or slow to respond. For example,
following the Fukushima nuclear disaster in 2011, the Japanese public supplemented
authoritative government sensors with user-generated content. Individuals through-
out the country bought personal Geiger counters and contributed to a crowdsourced
Geigermap. 1

Crowdsourced Damage Assessment

Remote sensing data (photos) acquired by the Civil Air Patrol were assessed for
damage by thousands of people across the world. The photos were placed on a
Hurricane Sandy Google Crisis Map website (Fig. 14.3 ) for the public to assess
visible damage through a crowdsourcing portal supported by MapMill. This yielded
a large damage assessment dataset generated from crowdsourced, non-authoritative,
nontraditional sources. The photos were also made available online through a
Federal Emergency Management Agency (FEMA) website for residents to search
by street address to see what, if any, damage their homes may have sustained.
The crowdsourced damage assessments of photos captured between October 31
and November 11, 2012 for the area from 33N to 26N latitude and 90W to 84W
longitude were downloaded directly from MapMill. Because of the large volume
of photos and the scale of the domain, the photos were aggregated into a 500 m
grid structure. The value for each grid point is a function of the number of images
present in each grid and their average crowdsourced damage assessment. As a result,
each grid has a value from 1 to 10, with 1 representing no damage and 10 severe
damage/flooding.

Volunteered Geographic Information (VGI)

VGI was ascertained from YouTube videos which documented flooding and damage
in New York City following Hurricane Sandy. The data were collected from a
Hurricane Sandy Google Earth website where YouTube videos were supplied by
Storyful. YouTube, a video-sharing website, is utilized by millions of people for the
sharing of videos covering a wide range of topics and experiences. Through this
site the public voluntarily shares information, often documenting damage resulting
from natural hazards. The videos were provided with geolocated information and
were visually assessed by the authors. The small number of videos (n D 15)did