Quick Terrain Analysis in Global Mapper Mobile

Global Mapper Mobile® is a useful field data collection tool for any map user in need of data reference, editing, or collection on a mobile phone or tablet device. Along with the viewing and creation of digitized vector features in the app come quick terrain analysis tools for key functionalities. Unlocked with a subscription to the Pro Module in Global Mapper Mobile, available terrain analysis tools are: Contour Creation, Volume Calculation, and Viewshed Analysis.

All tools to operate on, query, or create data in Global Mapper Mobile can be found in the toolbox located at the bottom left corner of the interface. Tapping on the toolbox icon, which conveniently indicates the active tool in the icon, opens the Tools Menu allowing a tool to be selected for use.

Contour Creation

Debuting in version 3.0 of the mobile app, contour generation is the newest addition to the analysis tools in Global Mapper Mobile Pro. The mobile contour creation tool relies on loaded terrain data to create a new layer of vector features describing the terrain. While shaded terrain data is a useful visualization of terrain change in a 2D map view, contour lines can help to describe the steepness of the elevation change. Where contour lines are stacked close together the terrain is steeper, which combined with the elevation value coloring provides Global Mapper Mobile users with a more comprehensive description of the terrain in the map area.

To generate a layer of contour lines in Global Mapper Mobile Pro, open a map containing a layer of terrain data and tap the Toolbox to select the Contours tool. Similar to options in Global Mapper® desktop, the Contour Generation Options in Global Mapper Mobile Pro allow the creation of a fill set of contour lines at a given interval, or lines tracing only a single elevation. Additionally, the range of elevation over which the contour lines are generated can be set, the default is the range of the loaded terrain data. Other options include interpolation over small gaps in data, unit labels, line smoothing for more aesthetically pleasing lines, and a discard of closed contour lines below a set length threshold.

Volume Calculation

A tool for Volume Calculation has been in Global Mapper Mobile Pro for a few versions now. As a terrain analysis tool, the calculation relies on loaded terrain and the bounds for the operation are set by a selected area feature in the map. Again, accessed from the toolbox, the Volume tool will only open if terrain is loaded and an area feature is selected.

In the Volume Calculation tool, there are three options for the elevation of the selected area: flat base, vertex elevations, or terrain elevations. The first option, Cut and Fill (flat base) asks the user for a value to use as the area elevation. The second option, Cut and Fill (vertex elevations) uses the elevations of the selected feature vertices; the user can also view the vertex elevations as a list from this option. The third option Terrain Elevations samples the loaded terrain along the boundary of the selected area. Regardless of the method selected, the tool then creates an interpolated surface across the selected area using the elevations dictated by the Volume Calculation Options and compares that with the terrain within the selected area to calculate the volume.

New in version 3.0 of Global Mapper Mobile Pro is a Volume Calculation report screen with the option to add the calculated values to the selected vector area. This allows the results of the volume calculation to be attached to the vector area in the map for saving and sharing.

Viewshed Analysis

The third terrain analysis tool in Global Mapper Mobile Pro is the Viewshed tool. Useful for quick line-of-sight analysis in Global Mapper Mobile, the Viewshed tool uses a selected point or the GPS location to calculate the visible, or hidden, areas based on loaded terrain data. Being able to use the GPS location in the viewshed calculation allows users to complete a visibility calculation relevant to their current position in the field. Learn more about using the Viewshed tool in Global Mapper Mobile Pro in this blog.

From reference maps to collecting GPS-informed data, Global Mapper Mobile can get the job done. Available on iOS and Android mobile devices, download the free app today! For more information on subscribing to the Pro Module for advanced options and analysis tools in the app, visit bluemarblegeo.com/global-mapper-mobile.