GIS 5100 - Lab 4 - Visibility Analysis

SECURITY CAMERA PLACEMENT AT BOSTON MARATHON FINISH LINE

In Lab 4 we learned about several new tools in the Spatial Analyst and 3D Analyst toolboxes.  Using DEMs we focused on the two general types of visibility analysis: viewshed analysis and line-of-sight analysis.  The primary tools we used to perform the assigned tasks were viewshed, line of site, and visibility.   We also used the Extract Values to Points tool to perform additional analysis of one task.  

In Part C of the lab we were asked to view provided LiDAR data using the LAS Toolbar. Next we used the LAS Dataset to Raster tool to generate a DEM from the LiDAR data.  Our visibility analysis used this DEM along with a provided camera location to analyze visibility at the finish line of the Boston Marathon.   Using the DEM, an orthographic image of Boston, the study area boundary and the finish line, we were tasked to locate two additional cameras to provide the best possible coverage for the street segment where the finish line was located.  The visibility tool provides more options allowing for height offsets and view angle settings.

The original camera was located west of the finish line at a height of 100 feet and a viewing angle of 90 degrees.

I placed my 2^nd camera northeast of the finish line on top of a corner building with an offset of 100 ft using the identify tool and the elevation raster to determine the estimated height of the building.  The starting horizontal angle was 180 and the ending horizontal angle was 270 to create a viewing angle of 90 degrees.

I placed my 3^rd camera slightly northwest of the finish line on top of a building parallel with the finish line road segment.  Using the identify tool and elevation raster I estimated the building height at 165 ft and set my OFFSETA value.  The horizontal starting angle was 100 and the horizontal ending angle was 190. 

I also slightly changed the starting and ending angles for the 1^st camera to a horizontal starting angle of 350 and an ending angle of 80 for optimum coverage.

The assignment mentions using a combined set of three cameras for the analysis but I found it difficult to find starting and ending angles that would best combine coverage of the three cameras together.  It seemed best to perform a visibility analysis showing the coverage area from each camera location (and height) and display them individually and show the overlap areas as well as the individual coverage.

I also was unable to figure out how to remove the Not Visible classes from the Legend.  I tried using layer properties and properties within the Legend but was unsuccessful.

Visibility Analysis - Security Camera Placement at Boston Marathon Finish Line

I enjoyed this lab even though it was time consuming especially due to some travel commitments I had this week.   There were several great ideas posted in the discussion forum for a variety of applications for viewshed and line of site analyses.