GIS5100 Module 3: Visibility Analysis

    Module 3 in Applications in GIS provided a change of pace. This module prompted us to complete selected courses from ESRI (below):

  • Introduction to 3D Visualization
  • Performing Line of Sight Analysis
  • Performing Viewshed Analysis in ArcGIS Pro
  • Sharing 3D Content Using Scene Layer Packages

It’s important to know that to create a 3D map, we need another coordinate than the typical x, y coordinates used in mapping. The z- value is needed to create height – not exclusively, as it can represent other attributes such as density or precipitation, but in these exercises, the focus is more so on elevation. We can use a 3D scene in ArcGIS, ensure there is an elevation source, and use extrusion to visualized data in 3D.

Line of Sight analysis allows us to determine obstructions if a target point is hidden, as well as the visibility along the line of sight from an observer point. We performed Line of Sight Analysis using a Construct Sight Lines (3D Analyst Tools) to create sight lines, the Line Of Sight (3D Analyst Tools) tool to determine visibility along the sight lines, and the Add Z Information (3D Analyst Tools) tool to calculate the length of our sight lines.

Viewshed analysis in ArcGIS Pro allows us to see what areas are visible from vantage or observer points. By default, the Viewshed (3D Analyst Tools) tool reflects visible light, but can model other wave-based items (radar, etc.) by adjusting the refractivity coefficient. Adding certain fields, such as distance or angles, to the input feature class can help specify the output of the Viewshed tool. This tool can be used to see the coverage of street lights, how terrain may obscure buildings, and so on.

ESRI also provided us insight on using ArcGIS Pro to author a 3D scene for creating a scene layer package for online publishing by using the Create 3D Object Scene Layer Content tool. In ArcGIS Online, we added our created scene layer package to our Content and used Create A Hosted Scene Layer so as to have the option to publish our data to the public.

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