Point-to-Point Calculator

The Point-to-Point Calculator has three different operations which can be performed: Convert, Forward, and Inverse.

For a limited time the Point-to-Point Calculator can be used at no cost. However, you must be logged into GeoCalc Online using an account tied to a Geographic Calculator order. If you have any issues with this process, please contact our Sales Team (orders@bluemarblegeo.com).

Convert, Forward, and Inverse operations in the Point-to-Point Calculator all require an source coordinate and system, and a target coordinate system. Click on the system name to browse for and select the source or target coordinate system. When browsing for a system, note the Favorites group allowing easy access to objects tagged as a Favorite. The source and target systems can also be set with the Search Results Actions Set as Converter Source and Set as Converter Target.

The units for the source and target systems will be automatically populated with the units defined in the selected objects. Click on the system units value to change the source or target units for the calculation. The Format button allows the unit display settings to be customized for the coordinate format and precision.

After completing a calculation of any type in the Point-to-Point Calculator, a report is generated and can be viewed using the Report button. This will open a new tab containing a summary report of the calculation including source and target coordinates, systems, transformations, and parameters.

Convert Operation

Enter a coordinate, select source and target systems , and select a transformation to convert the source point to the new coordinate system.

The source and target systems can be populated two ways:

  • From the search page, use the Action button and choose Set as Converter Source or Set as Converter Target to populate the Convert page.
  • On the convert page press the gray system button to navigate the systems by folders of type and region.

The point values will appear red when they have been edited manually and have not been calculated or recalculated.

The bar below the point converter will inform you of any messages.

How to set up the Convert Operation:

  1. Under Source Point Coordinate System, select the coordinate system that corresponds to the source point coordinate that is to be converted:
    • Click in the System field to bring up a selection dialog for the horizontal coordinate system. Expand and navigate through the menus on the left side to locate your source horizontal coordinate system on the right side of the dialog. Select the horizontal CRS on the right side of the dialog and click OK to populate the System, Datum, and Units fields.
    • Click on the Vertical field to bring up a selection dialog for the vertical coordinate system. Expand and navigate through the menus on the left side to locate and select the vertical coordinate system on the right side of the dialog. Click OK to populate the vertical field.
    • Use the Format option to the right of the Units field to specify the format of the coordinates.
  2. Under Source Coordinate Point Definition enter the name and coordinates for the source point.
  3. Select the target coordinate system (using the same steps as above) to convert the coordinate to, under Target Point Coordinate System.
  4. If necessary, select a transformation by clicking Select Transform below the transformation box in the center of the page.
    If no transformation is needed, a message stating this will appear in the display box. If no valid transformations are found between the two datums, a warning message will display.
    • Expand and navigate through the menus on the left side to locate and select the transformation on the right side of the dialog:
      • The top level *All* folder will display all possible transformations.
      • The Datasource Transformations folder will contain all single Datum Transformations that can be applied, in addition to any Concatenated Transformations available. These will be listed under the same foldering scheme as the main datasource. A Coordinate Transformation may be a single datum transformation, a pair of datum transformations, or a direct transformation using some alternate calculation, such as an Affine Parametric transformation.
      • Additionally, there may be a folder for transformations that consist of two transformations via an intermediate datum. In this case, a pair of Datum Transformations will be displayed. Pairs of transformations displayed in this folder are created on-the-fly, and will correlate the Coordinate Transformations that are defined in the datasource between the underlying geodetics of the source and target coordinate systems. These transformations will be found in Generated Transformations.
    • Click on the Transformation’s name to select it, then click OK to return to the main job page. The selected transformation will be shown, in addition to the Geoid model being used if there is a Vertical Transformation.
  5. Click Calculate to convert the point and populate the Target Coordinate Point Definition fields.

Forward Operation

A Forward calculation is used to compute a new coordinate that is a given distance and azimuth away from a starting coordinate. The conversion will be calculated using either Geodesic (Great Circle), Rhumb Line (Constant Azimuth), or CCG. To complete a Forward calculation, you must enter:

  • A target coordinate system (on the same Datum as the starting coordinate)
  • A starting coordinate and it's coordinate system
  • Distance and Azimuth ahead from the starting coordinate (or CCG string, in the case of the CCG method)

Setting up a Forward operation will be similar to the Covert operation, as described above, with one exception. You will specify method parameters rather than transformation parameters.

Inverse Operation

An Inverse calculation computes the distance between two known coordinates on the same datum. The result may be calculated using Geodesic, Rhumb, or CCG methods. Both the source and destination points must be referenced to the same geodetic datum.

This is also true for Geocentric coordinate systems that are 3 dimensional by nature. 3D Cartesian coordinates will be reduced to the surface of the datum.

Setting up a Inverse operation will require setting up Sours and Target Coordinate Point Definitions, along with Source and Target Point Coordinate systems. The Distance, Azimuth, and Bath Azimuth will be calculated from those parameters.