Module 5 - Applications in GIS - Visibility Analysis

Security Camera Coverage of the Boston Marathon Finish Line

This week's Application in GIS was visibility analysis.  We studied how viewsheds and lines of sight are developed in ArcGIS.  A viewshed is a representation of everything that is visible or not visible from particular observation points or along lines of observation such as roads.  A line of sight is a single line between an observer and a target, showing which portions of the line are visible to the observer and which are not.  Applications that we worked with included an analysis of the visibility of landscapes in Yellowstone National Park and the best placement of security cameras at the finish line of the Boston Marathon (above).

For the Boston Marathon exercise, we started with the view that a single camera has (#1 on the left), then experimented with the placement, angle and height from the ground of two more.   For this, we used Viewshed and Visibility tools in ArcMap, adjusting the positions of cameras #2 and #3, as well as their height from the ground and the 90 degree angle they cover.  This figure shows my best result for surveillance camera coverage of the finish line. The map indicates areas of visibility from all 3 cameras (yellow), any 2 cameras (green) or only 1 camera (purple).  Areas that are not seen by the cameras at all have no color overlay.

Here is a table with the details of the camera parameters.  (They are numbered 1, 2, and 3, from west/left to east/right.  In this figure the camera positions are represented by red dots, but are a little hard to see.)

Surveillance Camera Parameters

All in all, this week's topic was really interesting, and I continue to be amazed at the versatility of ArcGIS!