Geographic Calculator delivers powerful coordinate conversion and transformation tools to anyone requiring accurate horizontal or vertical positioning. Known for its accuracy, comprehensive geodetic parameter database, and format support, Geographic Calculator is unsurpassed in the fields of geodetic science and geomatic calculation. Version 2023 SP1 improves upon the software’s capabilities with notable new features such as LAZ format support, a four-parameter Helmert Transformation method in the Best Fit job, and support for several new transformation methods, including the Natural Resources Canada BYN grid format, New Zealand Deformation Models, and a parametric Similarity Transformation. Together, these enhancements continue Blue Marble’s commitment to support users of geodetic data, including surveyors, energy and seismic data managers, and many others.

LAZ format support (compressed LAS point cloud)

Lidar processing—particularly vertical datum transformation—is a key feature of Geographic Calculator. Version 2023 SP1 now supports the LAZ format, a compressed version of the popular LAS point cloud data format. In addition to vertical transformations, horizontal transformations, and reprojection, and LAS version translations (among versions 1.0 through 1.4) can be performed during processing in the Vector Data Conversion job. LAZ point clouds can also be displayed in the application’s Viewer.

Best Fit job: Four Parameter Helmert Transformation Method

For many years, the Point Database Best Fit job has been very popular for deriving a fitted coordinate system that relates local grid coordinates to a known coordinate system via a series of control points. Now, in the tradition of user-driven development, Blue Marble has added a 4-parameter Helmert option to the Affine through 5th-order polynomial methods to derive these fitted systems. This Helmert method allows for a single scale factor and rotation (of the X-Y plane about the Z axis) and translations in X and Y.

“Why can’t I export a fitted coordinate system as a ‘Well Known Text’ or ‘PRJ’ file?”

While we’re on the subject of fitted coordinate systems, it may be worthwhile to answer this question we receive on occasion. The explanation involves consideration of how a known coordinate system is defined vs a fitted coordinate system, and why they are different.

A known coordinate system is defined by standard parameters such as ellipsoid, datum, projection (if applicable), units, and identifiers. These parameters allow the system to be used in coordinate conversions or transformations. By its nature, a local coordinate system has few, if any, of these parameters, but the Best Fit job creates a transformation bridge to a known base system. While the fitted coordinate system allows coordinates in the local system to be converted or transformed, the fitted system contains transformation parameters, not the standard coordinate system parameters found in a known system definition that can be exported to a “Well Known Text” or “PRJ” file.

New Transformation Methods

Natural Resources Canada BYN Grid Format

A new natively supported geoid transformation in GeoCalc 9.1 is the BYN format. Natural Resources Canada (NRCAN) uses geoid grids in this format for the CGVD vertical datum of various epochs and combinations of target systems. One of the unique things about geoid transformations, in general, is that no one standard grid format has taken over in terms of common use and popularity around the world. In the realm of horizontal transformations, there have been a few common standards used worldwide; notably, the NTv2 grid file standard created by the Canadian government for transformations between NAD27 and NAD83. NTv2 grids have since become very common, with many other governments around the planet adopting the use of this format.

Presently, vertical transformations do not have a clear standard. Almost every geoid in the database has a unique grid type in which its data is stored. The formats for storing geoid grid data are chosen individually by the survey authority for the country where the data applies, and extremely few share a common data format. To implement geoid grids in GeoCalc, it was often simpler to restructure the data into an internal format that was already supported.

Then along came BYN, with several additional grid tables being published, handling many iterations of transformations for the Canadian Vertical Geoid of 2013 and the CVGD 2013a variants. Now, enough new grids are using the BYN format that it simply made sense to add support for the file format itself, such that when new grids are published in the future, GeoCalc SDK users will be able to add them without needing to update their GeoCalc SDK libraries.

New Zealand Deformation Models

Another new method in GeoCalc is a deformation model for New Zealand. Deformation models are particularly interesting because they acknowledge that the world is moving. As Dave Doyle, a retired Chief Geodetic Surveyor for the United States, says, “Everything is in motion, all the time!”. Modern coordinate systems are beginning to acknowledge the motion of the Earth’s crust with the development of velocity models that map how the tectonic plates slowly drift around the surface of the planet. However, this slow, steady motion is not necessarily uniform. The plates and surface sometimes warp, twist, crunch together, pull apart, and generally change shape. Localized motion is a complicated factor in dynamic coordinate systems, and that’s where deformation models come in.

These models are time-based by nature and are used to calculate where things were based on the distortions of the entire control networks. Deformation models help us to figure out where things are when a sudden shift in locations occurs, such as before and after an earthquake, but they also apply to slower motions that change the shape of a plate over time. The New Zealand deformation model is one such example. It factors in changes to the New Zealand landmass in snapshots of time, helping to calculate positions at the various points in time around seismic events. This allows specific models to be chosen to reflect a period of time where data may be applied from a particular epoch, similar to how a conventional time-based transformation helps more precisely model the changing earth.

Parametric Similarity Transformation

GeoCalc and the Geographic Calculator now support the “Similarity Transformation” operation that was defined by the IOGP’s EPSG working group. This operation is a four-parameter mathematical transformation that can be used to identify the relationship between two given coordinate reference systems. For many years, Geographic Calculator has provided a similarity transformation in two jobs under the name “Helmert Four Parameter.” But whether it be the Point Database Scale and Translate job or the Vector Data Conversion job (manual transformation option), the parameters are entered manually and can only be saved within the job. The new method allows users to create and save a custom Similarity Transformation object in the Datasource for use across jobs. They can even be exported and shared with other users.

Explore all the new features available in Geographic Calculator 2023 SP1 by downloading a 14-day free trial today! If you have any questions, please contact us.

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