May 4, 2021

What’s New in GeoCalc 8.1

Written by: Mackenzie Mills


The Blue Marble Geographics GeoCalc Software Development Kit (SDK) is a fully object-oriented class library utilized in many geospatial and geodetic software programs for geodetic data management and conversion. With this development kit being widely used throughout many industries, GeoCalc is regularly updated to stay current with the latest geodetic standards.  

New Magnetic Declination Models

Version 8.1 of GeoCalc now supports two newly released magnetic models, WMM2020 and IGRF13. These models, both released in December 2019, are the current geodetic standards for magnetic declination. As Earth’s magnetic field changes, how magnetic north aligns with true or geographic north also changes. Over time, as these shifts occur, new models are needed to describe the changing relationship between magnetic north and true north, which is especially important for navigation applications.

The World Magnetic Model of 2020 (WMM2020) is produced by The US National Geospatial-Intelligence Agency (NGA) and The UK Defence Geographic Centre (DCG) based on collected data and continuous modeling of the Earth’s magnetic field from space. This model replaces the previous WMM2015 and WMM2015v2 and models future changes up to 2025. The WMM2020 is the standard for various government and defense agencies and is used in many navigation systems. 

The International Geomagnetic Reference Field 13th generation (IGRF13), developed by the International Association of Geomagnetism and Aeronomy (IAGA), models the Earth’s magnetic field from 1900 to future predictions in 2025. As an international effort, organizations from nine countries contributed data and models to describe the 2015 definitive field, the projected 2020 field, and predicted change from 2020 to 2025. In late 2019 multiple models were compiled into IGRF13. 

Projections and Transformations for Czechia

GeoCalc 8.1 now supports the Krovak Modified projection. This projected system produced by the Czechian government is an updated version of the Krovak projection that includes a polynomial correction. This system is used as an output for the transformations in the ETJTZU Library.

Transformations from the ETJTZU Library, updated last in 2019, have been developed for Czechia and are now supported in GeoCalc 8.1 (C++ version). These transformations bring the Czechian standards into GeoCalc and provide parametric transformations between the Krovak grids and the widely used systems WGS 84 and ETRS89. 

Improved Handling and Ease of Use

With GeoCalc users in mind, improvements are logically integrated to make the software easier to use. GeoCalc 8.1 offers updates for better handling of Areas of Use that cross the 180th meridian. With this enhancement, systems, and data crossing the antemeridian are more successful, improving program usability.

New user interface options to promote coordinate reference systems from Late Bound to Early Bound coordinate reference systems (CRS) types, helping to assist GeoCalc users in managing, adding, and editing the geodetic datasource. 


Additional updates related to the ease of use and operations of GeoCalc include enhanced reading of the CRS from GeoTIFF images, better handling of equidistant cylindrical projection types, and many others. 

The GeoCalc SDK allows developers to utilize the underlying geodetic library that supports the Blue Marble Geographic Calculator within their own programs. If you are interested in working with the GeoCalc SDK, visit our website to learn more and download a trial today. 



NOAA National Centers for Environmental Information, 10 Dec. 2019. 

BGS British Geological Survey. 



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