disaster-response applications. For
more on the organizational issues that
arose in this more structured aspect
of the search, see the longer version of
this article. 3
Polytechture. The software-devel-opment-and-deployment process that
emerged was based on groups of experts working independently. Some
of the more sophisticated software
depended on preexisting expertise
and components (such as parallelized
image-processing pipelines and sophisticated drift-modeling software).
In contrast, some software was ginned
up for the occasion, building on now-standard Web tools like wikis, scripting languages, and public geocoding
interfaces; it is encouraging to see how
much was enabled through these lightweight tools.
Redundancy was an important
theme in the process. Redundant ftp
sites ensured availability; redundant
drift modeling teams increased confi-
dence in predictions; and redundant
target qualification by experts provid-
ed both increased confidence and lim-
its on “responsibility bias.”
Perhaps the most interesting as-
pect of this loosely coupled software-
development process was the variety
of interfaces that emerged to stitch
together the independent compo-
nents: the cascaded Mechanical Turk
interface for hierarchical expertise in
image analysis; the ftp/email scheme
for data transfer and staging; the Web-
based “common operating picture”
for geolocation and coarse-grain task
tracking; the self-service “checkin/
checkout” interface for expert image
analysis; the decoupling of image file
access from image browsing software;
and the transactional workflow inter-
face for drift modeling. Variations in
these interfaces seemed to emerge
from both the tasks at hand and the
styles of the people involved.
The Web’s evolution over the past
decade enabled this polytechtural
design. Perhaps most remarkable
were the interactions between public
data and global communication. The
manufacturer’s specifications for
Tenacious were found on the Web, aerial
images of Tenacious in its berth in San
Francisco were found in publicly available sources, including Google Earth
and Microsoft Virtual Earth, and a for-
The volunteer
search team’s
experience
reinforces the
need for technical
advances in
social computing.
mer owner of Tenacious discovered the
Tenacious Search blog in the early days
of the search and provided additional
photos of Tenacious under sail. These
details were helpful for parameteriz-ing drift models and providing “
template” pictures of what analysts should
look for in their imagery. Despite its
inefficiencies, the use of Mechanical
Turk by volunteers to bootstrap the image-analysis process was remarkable,
particularly in terms of having many
people redundantly performing data
analysis. Beyond the Turk pipeline, an
interesting and important data-clean-ing anecdote occurred while building
the search template for Tenacious. Initially, one of Gray’s relatives identified
Tenacious in a Virtual Earth image by
locating its slip in a San Francisco marina. In subsequent discussion, an analyst noticed that the boat in that image did not match Tenacious’s online
specifications, and, following some reflection, the family member confirmed
that Gray had swapped boat slips some
years earlier and that the online image
predated the swap. Few if any of these
activities would have been possible 10
years before, not because of the march
of technology per se but because of the
enormous volume and variety of information now placed online and the
growing subset of the population habituated to using it.
Networked search. It is worthwhile
reflecting on the relative efficacy of
the component-based polytechtural
design approach, compared to more
traditional and deliberate strategies.
The amateur effort was forced to rely
on loosely coupled resources and
management, operating asynchronously at a distance. In contrast, the
Coast Guard operates in a much more
prepared and tightly coupled manner,
performing nearly all search steps at
once, in real time; once a planning
phase maps out the maximum radius
a boat can travel, trained officers fly
planes in carefully plotted flight patterns over the relevant area, using real-time imaging equipment and their
naked eyes to search for targets. In
contrast, a network-centric approach
to SAR might offer certain advantages
in scaling and evolution, since it does
not rely on tightly integrated and relatively scarce human and equipment
resources. This suggests a hybrid