This week took us to ESRI direct, utilizing ArcGIS Online and 4 different ESRI hosted training sessions. The theme? Visibility analysis. This week carries forward with our look at LiDAR last week, by continuing to use some similar products, working with elevation layers and overlapping features of varying heights, shapes, sizes, make up types (points, lines, polygons) to work with different portrayals of 3D information. The modules themselves were:
- Introduction to 3D Visualization
- Performing Line of Sight Analysis
- Performing Viewshed Analysis in ArcGIS Pro
- Sharing 3D Content Using Scene Layer Packages
These modules all served to highlight how helpful 3D data and information presentation or visuals can be in identifying patterns not seen in 2D. They aid in providing new perspective of vertical content, and provides an extra sense of realism with the ability to navigate and explore in a 3D manipulable environment.
One of the key takeaways was in understanding the difference between a local scene and a global seen. They both typically revolve around the scale of information you are working with, but more explicitly in how they convey real-world perspective vs real-world context. One key difference being if the curvature of the earth is a factor in your information presentation or not.
We continued to work with LAS data, DEM's or other forms of elevation layers, but also with Z-values which provide the third dimension for points, lines, and polygons.
For points, you could add a height extrusion, such as showing how tall trees are, or lamp posts. For lines, you could establish a standard height above ground for a fence line, or make a particularly uniform elevation boundary. Polygons with Z information gain new dimensions as the shapes are shown. From a square or circle in the 2D to a full 3D building structure.
Other analyses can then be done with a fully extruded 3D scene. Line of sight and viewshed analysis was a big part of this weeks training. These revolved around constructing sight lines, then building lines of sight. Whats the difference you ask? Constructing sight lines involves an observation point with known elevation and a target point with known elevation and generating a line between the two. Then, the line of sight utility is used to determine if there are any obstacles from the observer to the target. Buildings, terrain changes, trees or foliage features, etc can all block line of sight. A viewshed takes this a step further in being able to establish what is in view based on what elevation and field of view parameters.
To take it a step further and apply it to the real world, look at the news this week, there are all sorts of graphics being modeled and analyzed after former President Trump was shot at. Building models, sight line distances, camera vantage points, obstruction analysis. All going on in the real world this week is the exact substance of this module.
Regardless of the ongoing real world applications, this module was culminated in creating a shareable scene layer package. An example of the type of deliverable generated for this is below.
Overall, these are all hugely relevant skills for GIS applications. They allow you to explore your data more in depth and provide much more immersive presentations. Onto the next week.
V/r
Brandon
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