Using Vertical Exaggeration to understand terrain variation in ArcGIS Earth

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05-08-2017 11:51 AM
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In September, ArcGIS Earth 1.3 released with several new features, including a new slider control for vertical exaggeration (VE). Vertical exaggeration enables users to highlight slight deviations in elevation that are not visibly obvious across relatively flat terrain. Through ArcGIS Earth you can create high value visualizations using 3D, adding real world context that speaks to your audiences who are not familiar with interpreting geographic data and maps.


The picture below shows a 2D view of Hurricane Matthew’s path across Haiti, loaded into ArcGIS Earth from one of many publicly available sources of information on ArcGIS Online. (Simply right-click and select properties in the table of contents (TOC) to expose metadata for any dataset).

2D view of Hurricane Matthew’s path across Haiti

Hurricane Matthew devastated Haiti. The tropical cyclone crossed Haiti's western tip as a Category 4 storm and then traveled into Cuba and onto Florida and the Carolinas. Hurricanes are typically known to slow down or even change path when encountering land. Mountainous terrain can disrupt the center of circulation of the storm. Unfortunately, Haiti’s mountainous terrain was not enough to slow this powerful storm. Matthew’s track steered west, away from higher peaks like Massif de la Hotte (Enter ‘Massif de la Hotte’ into ArcGIS Earth’

s search locator to fly to the location) and over lower terrain. Zooming in and rotating the view, lets you appreciate this from a 3-Dimensional perspective. In the view below however, the mountain range looks almost flat and hardly discernible.

Mountain range looks almost flat and hardly discernable

To better understand the terrain variation in Haiti, ArcGIS Earth’s VE tool is used to adjust the VE value to 2.0 in the image below, increasing the vertical heights of the mountains. The terrain is enhanced and this visibly changes the appearance of the topography. (Vertical exaggeration is calculated by dividing horizontal scale by vertical scale. In ArcGIS Eart#h the VE scale ranges in values from 0 to 3.  A value of 0 renders all terrain in Earth at mean sea level.)

 

VE tool used to adjust the VE value to 2.0

Matthew’s path is shown against the backdrop of the ‘Imagery with Labels’ basemap in the above pictures.  Using a different basemap, the user may be able to understand the true terrain variation while still seeing the vertical exaggeration, setting the stage for a better understanding and context in any map. One of key advantages of using ArcGIS Earth is its access to multiple basemaps. Changing the basemap to ‘Topographic’ displays contours and shows the actual range of heights of the terrain, although exaggerated and highlights the path of the storm across Haiti.

Topographic basemap displays contours and shows the actual range of heights of the terrain

ArcGIS Earth is a highly powerful, yet lightweight client tool that is fully integrated into the ArcGIS Platform. Its added value comes from leveraging thousands of robust datasets in the Living Atlas, ArcGIS Online as well as those you published and accessible through your organizations Portals. GIS experts, senior executives, managers, analysts, even casual users work with ArcGIS Earth to realize the bigger picture and uncover spatial relationships. In this example, the terrain over Haiti was exaggerated by ArcGIS Earth’s VE tool to highlight the mountainous terrain. ArcGIS Earth allowed us to change the basemap and understand both the storm's path and variation in height of the terrain. Try out this example or experiment with a host of other datasets with the latest release of ArcGIS Earth 1.3 here!

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