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How do I create a local system?
There are two main ways to create a local system in tcpGPS: using point pairs (with visual map assistance) or by entering specific parameters.
You can watch this video for more information.
It is important to note that you cannot create a local system if one is already in use; you must remove the current one before starting the process.
This method allows you to define a local transformation by adding and editing control points. The source points are those already contained in the project. It is recommended to use the device in horizontal (Landscape) orientation to view the Global Map and the Local Map simultaneously.
DO NOT import points into the project to use them as target/destination points in a local system. Import the file within the local system option.
Transformation types: You can choose between 2D/3D Displacements and 2D/3D Helmert.
Point insertion:
Manual/GNSS: You can manually enter the coordinates or capture the source point directly with the GNSS receiver in real time.
Import: It is possible to import point files (formats
.txtor.pun) to use them as destination coordinates. If the point numbers match the source ones, the application will create the pairs automatically.
Integrity management: If you enter a point number that already exists in the database, the coordinate fields will be automatically filled with the saved data and cannot be modified, protecting the integrity of the previous information.
Precision analysis: In the numerical section, you can view the residuals (differences between source and destination) and the Root Mean Square Error (RMSE) to validate the quality of the transformation.
This method is performed via the path Menu > Local Systems > Create By Parameters and generates a file with the extension .ntr.
Depending on the type of transformation selected, the system will request different data:
2D/3D Displacement: Displacement values on the X, Y, and (optionally) Z axes.
2D Helmert: X and Y displacement, rotation, and scale factor.
3D Helmert: Displacements (X, Y, Z), rotations on the three axes, and scale.
Important note on format: All rotation data must be entered in the Degreesº Minutes’ Seconds” format, including the corresponding symbols.
Once the local system is created, it will be in the project folder, and you can change it by going to Project > Information.