March 29, 2022

What is GeoCalc Mode?

Written by: Mackenzie Mills


Global Mapper, the complete GIS software program containing tools for everything from data creation to analysis and 3D viewing, also contains the capability to reproject data. This is an essential part of a GIS program as data is often gathered from many different sources and may be in reference to different projections and geodetic systems. The early bound reprojection capabilities in Global Mapper allow data from different sources to be displayed and analyzed together in a single workspace.

Geodesy is the science of measuring and understanding the shape of Earth and the mathematical methods used to model earth and the coordinates used to pinpoint locations. Some coordinate reference systems, like geographic latitude/longitude cover the entire earth, while others are best suited for smaller areas of use. The reprojection capabilities in Global Mapper perform simple, early bound datum transformations between supported geodetic systems. All transformations in Global Mapper are all early bound to WGS84, a current global data used by many worldwide coordinate reference systems. The supported projections and datums can be explored further in the Global Mapper knowledge base.

To gain further control over how your data in Global Mapper is transformed, Blue Marble’s Geographic Calculator, a program for advanced geodetic transformation and coordinate system management, can be used in conjunction with Global Mapper. This collaboration between Blue Marble programs is GeoCalc Mode, a specialized geodesy tool that can be enabled in the Global Mapper user interface. GeoCalc Mode takes the advanced coordinate transformation capabilities of Geographic Calculator and makes them accessible through Global Mapper, allowing users to select from a wider array of geodetic systems and transformations, including vertical reference systems.

offset between layers that can be correction with Vertical reprojection
As the use of 3D data becomes more prevalent in all types of analysis, GeoCalc Mode helps users to transform vertical systems to accurately display and combine 3D data from different sources.

To access GeoCalc Mode, both Global Mapper and Geographic Calculator must be installed and licensed on the same machine. Using the GeoCalc Mode button on the GeoCalc Mode toolbar, the enhanced transformation capabilities of Geographic Calculator can be brought into Global Mapper. The program interface will not change in an immediately obvious way when GeoCalc Mode is enabled, but as you go to reproject data, note that the Configuration > Projection interface in Global Mapper has changed.

GeoCalc Mode in Global Mapper for reprojections
GeoCalc Mode provides users with full control over the horizontal and vertical transformations used to convert data in Global Mapper.

GeoCalc Mode accesses Geographic Calculator’s geodetic datasource allowing users to select both a horizontal and vertical system to use for data display in and export from Global Mapper. Once the desired systems are selected from the Datasource browser in Global Mapper’s Configuration > Projection dialog, specific transformations need to be selected for each layer in the workspace. The transformations for each data layer can be manually selected, or the most accurate transformation will be automatically selected if the Auto-Select option has been enabled from the GeoCalc Mode toolbar. The coordinate reference systems and transformations selected through the Projection settings are then used to display the data in the workspace and will be used when data layers are exported.

While the advanced geodesy provided by Geographic Calculator and GeoCalc Mode may not be necessary for all workflows in all industries that use Global Mapper and GIS programs for analysis and visualization, understanding the geodetic systems used in a project is an important aspect of GIS work. Fortunately, the Blue Marble programs work together to provide a full set of tools for advanced geodesy and complex data analysis.

Want to work in GeoCalc Mode? Download a free trial of Global Mapper and Geographic Calculator to explore the programs separately and how they work together to support advanced geodesy, visual mapping, and analysis. If you have any questions, contact us!

*To learn more watch a short video on this topic on the Blue Marble YouTube page.

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