Visibility Analysis and Camera Surveillance

Modern society, in public places, is under nearly constant video surveillance.  (http://www.cnn.com/2013/04/26/tech/innovation/security-cameras-boston-bombings/) The merits and ethics involved in public video surveillance are endlessly debatable, but the logistic issues inherent in constant camera visibility do present some uniquely challenging problems involving spatial analysis.  Finding the best locations and viewing angles for cameras capturing the finish line of the Boston Marathon is the task du jour, aided by use of the 3-dimensional spatial analytic tools available in ArcGIS.

Above is the location in Boston where the finish line of the marathon is placed- symbolized with a pink star.  The purple circles are the camera locations, and the shades of blue and green are locations visible from one, two and all three of the cameras.  The cameras are placed to maximize the viewing angles and coverage of the finish line and the street on that block.  The blue and green colors are the output generated by the 3D Spatial Analyst to indicate the views offered by this combination of cameras, which is created with the use of an elevation layer that indicates the location and height of visible obstructions (buildings, etc).  The camera's locations are also input with a vertical offset, as if they were being placed on the top of the adjacent buildings, which further increases the size of their field of view.  If one were attempting to assess the placement of surveillance equipment these tools would be invaluable, as they would provide a convenient means of evaluating potential camera locations by indicating specifically which areas are visible from which cameras.