GIS Module 3 - Visibility Analysis

Module 3 of Applications in GIS was a four-part assignment that covered different topics of the ESRI tutorials page. It consisted of four hands-on tutorials, four quizzes, and four introductions to the various capabilities of this extensive software platform. The four tutorials were: Introduction to 3D Visualization, Line of Sight Analysis, Viewshed Analysis, and Sharing 3D Content using Scene Layer Packages. Each are discussed in detail below.

3D Visualization

The first ESRI tutorial was an introduction to the 3D capabilities of ArcGIS. While all of the data was provided in 3D format, it was a neat introduction into 3D navigation [slightly different than navigating a 2D map], the difference in various 3D map scenes [Local and Global], and the 3D symbology that is included in the software package. The ESRI documentation provides a 3D Workflow page that provides a lot of introductory information; this page can be viewed by clicking here. As shown in the map below, we were provided with all the required data to create a realistic, three-dimensional map of San Diego, California.

Line of Sight Analysis

The second ESRI tutorial was a lesson on Line of Sight [LOS] analysis. LOS is a visualization of which points [along a line] can be seen from an observation point; the ESRI documentation for this geoprocessing tool can be view here. This tutorial was based on the 3D knowledge obtained in the first lesson, so it was important to work these in order. The subject of this lesson was to analyze how much security coverage there was on a parade route that progresses through downtown Philadelphia, PA. Essentially, two security observation points were chosen, and the tutorial provided an analysis of how much of the parade route was visible from those two security observation points. As shown in the image below, the two security observation points are symbolized by reddish colored dots on the roofs of two buildings located in the central business district. The LOS analysis was performed at 30 feet increments [a parameter of the geoprocessing tool], and the visible points are notated with lime green lights. The choice of these two security observation points provides a great deal of visual coverage while the parade is taking place.  

Viewshed Analysis

While Line of Sight Analysis function executes among points or along lines, the Viewshed Analysis is performed over geographic areas, as in 360° from the observation point [unless set differently in the user parameters]. Click here to view the ESRI documentation for this ArcGIS Spatial Analyst tool. In the third tutorial, property owners of a campground wanted to illuminate their property using two specific lighting fixtures; specifically, they knew where the fixtures were going to be placed but needed to know at what height the fixtures needed to be placed to achieve 50% illumination, or greater. As shown in the map below, a viewshed analysis was performed [according to the specifications of the light fixtures] at a height of 3 meters and at a height of 10; it is obvious that the 10-meter height exceeds the illumination requirement while the 3-meter height is substantially lower.

Sharing 3D Content Using Scene Layer Packages

The fourth and final tutorial was taking what was taught in the previous modules [specifically the Introduction to 3D Visualization Tutorial] and sharing it to the web. A great resource on this subject is the ESRI Share A Web Scene Layer documentation page, and this hands-on tutorial was a great introduction into Scene Layer Packages and sharing them to ArcGIS online. The final product was a 3D landscape of Portland, Oregon published to the web. A still image has been pasted below, and the 3D map can be viewed by clicking here.