The Point tool allows single-point calculations of numeric coordinates. This tool provides easy access for testing a transformation or map projection on a single point. Users can simply type the coordinates into the tool and choose an operation to perform. For processing lists of coordinates in spreadsheets or tabular data, see Point File.
The following three Operation Types are supported:
- Conversion converts or transforms coordinates between coordinate reference systems.
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Forward is used to compute a new coordinate that is a given distance and azimuth away from a starting coordinate. Both the source and destination points must be referenced to the same geodetic base coordinate system. Forward calculations follow one of three paths:
- Geodesic ("great circle" or the shortest path between two points on the surface of the ellipsoid)
- Rhumb Line (constant azimuth)
- Grid Distance (valid for projected "grid" coordinates only)
- Inverse computes the distance between two known coordinates on the same datum. The result may be calculated using Geodesic, Rhumb, or Grid (valid for projected coordinates only) calculation methods. Both the source and destination points must be referenced to the same geodetic base coordinate system.
Point Conversion
Point Conversion converts or transforms coordinates between coordinate reference systems.
To perform point conversion, the following will be needed:
- Enter a coordinate pair
- Select the known source coordinate reference system
- Set the desired target coordinate reference system
- If the source and target coordinate systems use a different geodetic datum, you will be prompted to select an appropriate datum transformation from the GeoCalc Datasource to convert the source point to the target coordinate system
- Optional: Enter the elevation value (Z) associated with the X, Y and set the source/target vertical coordinate reference systems to prompt vertical transformation
- Optional: a source and target date are required to access time-dependent transformations
How to set up the Point Conversion Operation:
1. Under Source Point, enter a name (optional) and the coordinates for the source point.
2. Select the source and target coordinate systems, along with a transformation if needed.
Select a Source and Target Coordinate System
- Use the Search button
next to the Horizontal system field to launch the selection dialog. On the left side of the selection dialog, use the text field to narrow the options or expand the folders to locate your source horizontal CRS on the right side of the dialog.
- The default is WGS 84 [EPSG:4326], but this can be changed in Settings. Recently used coordinate systems will populate the dropdown.
- Use the
icon to see information on the chosen CRS. Click your desired horizontal CRS, and the dialog window will close automatically. The system, datum, and units fields will update accordingly. You may optionally search for and change the source or target units if needed.
- Use the Search button
next to the Vertical coordinate system to launch the selection dialog. Setting a different vertical system on the target will prompt for a vertical transformation. Setting a vertical coordinate system is optional; if the data does not have elevation values, it will not be possible to assign a vertical coordinate system.
- The Date field will display if time-dependent transformations are enabled in Settings. Source and target dates are required for time-dependent transforms to display in the transformation selection choices.
- Set the Target coordinate system using the same steps as above.
- For more information, see Searching the Datasource.
Supported Coordinate Formats
Use the Format button to select the display format and precision for your input and output coordinates. This is very important for angular units.
You can enter latitude and longitude degree coordinate values in many formats, not only decimal degrees. The formats that you can select are shown below with an example (all examples represent the coordinate: South 44 degrees, 30 minutes, 15 seconds):
- DD. (example: -44.50416 or 44.50416 S)
- DD MM. (example: -44 30.2500 or 44 30.2500 S)
- DD-MM. (example: -44-30.2500 or 44-30.2500 S)
- DD MM SS. (example: -44 30 15.000 or 44 30 15.000 S)
- DD-MM-SS. (example: -44-30-15.000 or 44-30-15.000 S)
- DD.MM (example: -44.3025 or 44.3025 S)
- DD.MMSS (example: -44.3015 or 44.3015 S)
- Packed DMS (example: -44301500 or 44301500S)
- Packed DMS. (example: -443015.00 or 443015.00S)
- Packed DM. (example: -4430.2500 or 4430.2500S)
- Brazil ANP (example: -44:30:15,000)
The direction (N/S/E/W) can be entered as either a prefix or suffix.
Select a Coordinate Transformation
If the source and target coordinate systems use different geodetic datums, use the Choose Transformation field or Search button to select a valid transformation.
- Use the Search field to limit the results by text (or EPSG code) or expand the folders on the left side to select the transformation.
- The Datasource Transformations folder will contain any predefined objects organized into subfolders by transformation type (Concatenated, Datum, and Parametric).
- Additionally, when applicable, there may be a folder of Generated Transformations that consists of two transformations via an intermediate datum. 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 geodetic of the source and target coordinate systems.
- The transformations are limited by source and target CRS selections.
- The default Area of Use filtering also limits transformations to the coordinates being transformed. If the desired transform is not showing up, set "Ignore Area of Use" in Settings. This allows using a transformation outside of its defined AOU polygon.
- Click the desired transformation. If a vertical transformation is needed, you will be prompted to select one. Then, the Select Transformation dialog window will close automatically and the selected transformation(s) will be shown.
If no transformation is needed, an alert message stating this will appear in the display box.
If no valid transformations are found between the two datums the box will say "No Choices". If you do not select a CT before processing, you will receive a message similar to: "Info: Transform is not initialized, choose a transformation. If no choices are available, enable Allow “None” Transformations." The "None" transformation can be enabled in Settings.
3. Click Process to convert the point and populate the Target Point definition fields.
The Source and Target fields can be reversed using the arrow button. This reverses the Operation Direction (left-to-right versus right-to-left). The arrow will reverse to indicate the direction.
Forward
A Forward Calculation is used to compute a new coordinate that is a given distance and azimuth away from a starting coordinate. Forward calculations follow one of three paths: Geodesic (Great Circle), Rhumb Line (constant azimuth), or Grid distance (valid only for projected coordinates).
For both Forward and Inverse conversions, when height values are entered, the distance is scaled to a height above the ellipsoid.
Forward Calculation requires the following:
- Enter the starting coordinate pair as the source point
- Set the source and target coordinate system (target must be on the same datum as the starting source system)
- Enter the desired distance and azimuth from the starting coordinate
- Choose the line calculation method (Geodesic, Rhumb, or Grid)
How to set up the Point Forward Calculation:
1. Under Source Point, enter a name (optional) and the coordinates for the source point.
2. Set the Source and Target Coordinate System (remember the target system must use the same datum as the source).
Select a Source and Target Coordinate System
- Use the Search button
- The default is WGS 84 [EPSG:4326], but this can be changed in Settings. Recently used coordinate systems will populate the dropdown.
- Use the
- Use the Search button
- The Date field will display if time-dependent transformations are enabled in Settings. Source and target dates are required for time-dependent transforms to display in the transformation selection choices.
- Set the Target coordinate system using the same steps as above.
- For more information, see Searching the Datasource.
Supported Coordinate Formats
Use the Format button to select the display format and precision for your input and output coordinates. This is very important for angular units.
You can enter latitude and longitude degree coordinate values in many formats, not only decimal degrees. The formats that you can select are shown below with an example (all examples represent the coordinate: South 44 degrees, 30 minutes, 15 seconds):
- DD. (example: -44.50416 or 44.50416 S)
- DD MM. (example: -44 30.2500 or 44 30.2500 S)
- DD-MM. (example: -44-30.2500 or 44-30.2500 S)
- DD MM SS. (example: -44 30 15.000 or 44 30 15.000 S)
- DD-MM-SS. (example: -44-30-15.000 or 44-30-15.000 S)
- DD.MM (example: -44.3025 or 44.3025 S)
- DD.MMSS (example: -44.3015 or 44.3015 S)
- Packed DMS (example: -44301500 or 44301500S)
- Packed DMS. (example: -443015.00 or 443015.00S)
- Packed DM. (example: -4430.2500 or 4430.2500S)
- Brazil ANP (example: -44:30:15,000)
The direction (N/S/E/W) can be entered as either a prefix or suffix.
3. Under Transformation, select the Operation Type drop-down to select Forward.
4. Choose a method: Geodesic (Great Circle), Rhumb Line (constant azimuth), or Grid distance (valid only for projected coordinates).
5. Set the Distance. Click the m button to change the Units.
6. Set the Azimuth. Click the deg button to change the Units.
7. Click Process to convert the point and populate the Target Point definition fields.
The Source and Target fields can be reversed using the arrow button. This reverses the Operation Direction (left-to-right versus right-to-left). The arrow will reverse to indicate the direction.
Inverse
An Inverse Calculation computes the distance between two known coordinates on the same datum. The result may be calculated using Geodesic, Rhumb, or Grid methods. Both the source and destination points must be referenced to the same geodetic datum.
For both Forward and Inverse conversions, when height values are entered, the distance is scaled to a height above the ellipsoid.
Setting up an Inverse operation requires the following:
- Enter the source and target coordinates
- Set the source and target coordinate system (target must be on the same datum as the starting source system)
- Choose the line calculation method (Geodesic, Rhumb, or Grid)
The Distance, Azimuth, and Back Azimuth will be calculated from those parameters.
How to set up the Inverse Calculation:
1. Under Source Point, enter a name (optional) and the coordinates for the source point.
2. Set the Source and Target Coordinate System (remember the target system must use the same datum as the source).
Select a Source and Target Coordinate System
- Use the Search button
- The default is WGS 84 [EPSG:4326], but this can be changed in Settings. Recently used coordinate systems will populate the dropdown.
- Use the
- Use the Search button
- The Date field will display if time-dependent transformations are enabled in Settings. Source and target dates are required for time-dependent transforms to display in the transformation selection choices.
- Set the Target coordinate system using the same steps as above.
- For more information, see Searching the Datasource.
Supported Coordinate Formats
Use the Format button to select the display format and precision for your input and output coordinates. This is very important for angular units.
You can enter latitude and longitude degree coordinate values in many formats, not only decimal degrees. The formats that you can select are shown below with an example (all examples represent the coordinate: South 44 degrees, 30 minutes, 15 seconds):
- DD. (example: -44.50416 or 44.50416 S)
- DD MM. (example: -44 30.2500 or 44 30.2500 S)
- DD-MM. (example: -44-30.2500 or 44-30.2500 S)
- DD MM SS. (example: -44 30 15.000 or 44 30 15.000 S)
- DD-MM-SS. (example: -44-30-15.000 or 44-30-15.000 S)
- DD.MM (example: -44.3025 or 44.3025 S)
- DD.MMSS (example: -44.3015 or 44.3015 S)
- Packed DMS (example: -44301500 or 44301500S)
- Packed DMS. (example: -443015.00 or 443015.00S)
- Packed DM. (example: -4430.2500 or 4430.2500S)
- Brazil ANP (example: -44:30:15,000)
The direction (N/S/E/W) can be entered as either a prefix or suffix.
3. Under Transformation, select the Operation Type drop-down to select Inverse.
4. Choose a method: Geodesic (Great Circle), Rhumb Line (constant azimuth), or Grid distance (valid only for projected coordinates).
Click Process to convert the point and populate the Distance, Azimuth, and Back Azimuth fields.
The Source and Target fields can be reversed using the arrow button. This reverses the Operation Direction (left-to-right versus right-to-left). The arrow will reverse to indicate the direction.