when discussing large volumes of remote imagery, and various members of the amateur team voiced concern about personal privacy during the process. Although popular media-sharing Web sites provide widespread access to crowdsourced and aggregated imagery, they have largely confined themselves to benign settings (such as tourism and ornithology), whereas maritime SAR applications (such as monitoring marinas and shipping lanes) seem closer to pure surveillance. The potential for infringing on privacy raises understandable concern, and the policy issues are not simple. Perhaps our main observation on this front was the need for a contextual treatment of policy, balancing general-case social concerns against specific circumstances for using the data, in our case, trying to rescue a friend. On the other hand, while the search for Tenacious and its lone sailor was uniquely urgent for us, similar life-and-death scenarios occur on a national scale with some frequency. So, we would encourage research into technical solutions that can aggressively harvest and process imagery while provably respecting policies that limit image release based on context.

From Imagery to Coordinates

Here, we discuss the processing pipeline(s) and coordination mechanisms used to reduce the raw image data to qualified search coordinates— the locations to which planes were dispatched for a closer look. This aspect of the search was largely data-driven, involving significant technical expertise and much more structured and tool-intensive processes than those described earlier. On the other hand, since time was short and the relevant expertise so specialized, it also led to simple interfaces between teams and their software. The resulting amalgam of software was not the result of a specific architecture, in the usual sense of the word (archi- “chief” + techton “builder”). A more apt term for the software and workflow described here might be a polytechture, the kind of system that emerges from the design efforts of many independent actors.

Overview. The figure here outlines
the ultimate critical-path data and
control flow that emerged, depict-
ing the ad hoc pipeline developed for
Digital Globe’s satellite imagery. In
the paragraphs that follow, we also
discuss the Mechanical Turk pipeline
developed early on and used to process
NASA ER- 2 overflight imagery but that
was replaced by the ad hoc pipeline.