Lab 4: Applications in GIS

This weeks lab covered visibility analysis.  Visibility analysis can be applied to a lot of different situations such as observation points or fire towers.  This weeks lab focused on viewshed analysis, and observation point tools.  Part of the lab covered visibility analysis using 3D Analyst and the LAS Dataset tool.

The first part of the lab used the Viewshed tool with the summit points and the elevation raster.  I also used the Observer Point Tool with the same inputs.  Once I had the outputs, I used Extract Values to Points to determine which summit is viewed by the most observation points.

Polyline Visibility Analysis

The next part of the lab used polylines to determine which areas of Yellowstone National Park are visible from the roads.  The inputs used the roads polyline shapefile and the elevation raster.

Part three of the analysis uses the 3D analyst extension.  This allowed for me to see a 3D model of city of Boston.  Once the streetview was selected, I was able to rotate the model to see all angles.  Next, I used the LAS Dataset to Raster tool.  This creates a new finish line raster.  I added the camera shapefile and used the viewshed tool to see how much area is visible by the one camera.  I then adjusted the offset so the camera was considered elevated and could see around the buildings.

It was important to then determine the start and end angle.  This allowed for a more realistic visible area.  I added two more cameras and performed the same analysis.  After I had the viewshed, I adjusted the symbology to show what area is seen by 1 to 3 cameras.

The last part of the lab covered line of sight analysis.  For this analysis, I needed the Create Line of Sight tool.  I created a line that connect two summits.  To see more details, I opened the Profile Graph.  The blue dot shows an obstruction.  I also used the Construct Sight Lines tool to create lines between all the towers.  This allowed to see which summits are visible from each summit.