What’s that Mountain Over There? Using the Global Mapper Mobile Viewshed Tool

Have you ever looked out over a landscape and wondered, hey, what’s that mountain over there? Which island is that, across the bay? With Global Mapper Mobile Pro, the answer is in your pocket. Instead of squinting at Google Maps and trying to judge which hills are tall enough and at the correct viewing angle, the Viewshed tool in Global Mapper Mobile can highlight visible areas on the map for you. It’s as easy as streaming or loading an elevation layer, and clicking the Viewshed tool.

What is Global Mapper Mobile Pro?

Global Mapper Mobile Pro is a user-friendly tool for capturing and creating GIS data in the field using portable iOS and Android mobile devices. It utilizes the GPS capabilities of the mobile device, or Bluetooth-connected GNSS receivers, to provide situational awareness and locational intelligence for remote mapping projects. A perfect complement to the desktop version of Global Mapper, the mobile edition provides maps-in-hand functionality for engineers, surveyors, wildlife managers, foresters, and anyone who benefits from access to spatial data in remote locations.

What do You Need?

Here are the things you will need to have downloaded or will need to download onto your mobile device:

• Global Mapper Mobile Pro – The Pro version is required to use the Viewshed tool. This is available with a yearly subscription and can be purchased from the Apple app store, or from our website.
• *An elevation layer – a raster layer that represents the elevation of the terrain. This is what the Viewshed tool will read. Bonus, if you’re a GIS nerd like me, you can take trees, buildings, and other structures into account by creating a new digital surface model elevation grid from lidar data using Global Mapper desktop. The Max Binning method will create a layer that represents the tops of the trees. Just make sure the ground you will be standing on is included at your standing elevation!
• Recommended: *A topo map or similar map layer to display the names of landscape features.

*These can be streamed directly to your phone from the Online Data tool if you have cell service. You can also plan ahead and download the data as a package file from your desktop version of Global Mapper. For more information on that workflow, check out this blog on Data Sharing between Global Mapper Desktop and Global Mapper Mobile.

How to Use the Viewshed Tool 

So, how does it work? The viewshed tool runs an analysis and generates a layer that highlights all of the locations which are visible from a given point. In this scenario, the ‘given point’ is you. Although, you don’t even have to be there in person, because the Viewshed tool can also create viewsheds based on the location of a created point feature. If you are there in person, be sure your location is turned on!

With your data layers loaded, open the toolbox in the left-hand corner and choose Viewshed. In theory, you can use the default settings, but tweaking them can help narrow down to the specific area you are looking at. Let’s talk about what these settings mean.

Most of these settings can be left alone, but there are two you will probably want to change: 

• Radius – This is how far out you want the tool to look. You can attempt to gauge the distance between you and the mountain or back out of the Viewshed tool and use the Measure tool from the same menu.
• Transmitter height – This is the height above the ground that your eyeballs are in meters. Unless you’re standing on a tower, I would change this to “2”.  

For more information on the other settings, check out the tool specifications found in the Knowledge Base for iOS or Android. 

The Viewshed

The Viewshed tool will create a pink feature that highlights the visible areas on the map.

Once created, you can save this map to your device for future reference, or export it to the desktop version of Global Mapper. 

The Viewshed tool is one of the many features and tools available in the Pro version, accessed with a yearly paid subscription. To test out Global Mapper Mobile, download the free app from the iOS App Store or Google Play Store today and sign up for the upcoming webinar on August 2, 2023.