Tech Chat | How to adjust project coordinates when the base changes?
In surveying projects, sometimes we may need to update base station coordinates when many points have been measured. So how should we handle the previous measured points and continue surveying quickly?
In previous blogs, we have introduced the importance and one method of Grid Shift: Calibrate Point. Today, we will introduce another method – "add offsets to points at specified period" and comparing their difference in applications.
Read the previous blog:
Tech Chat | How to make your surveying more accurate? – Importance of Grid Shift
Application Scenarios:
During daily surveying, a common scenario arises – there are no known points in a project. To obtain precise coordinates for control points, we always need to conduct long-term static surveying. However, due to time constraints, we often start RTK surveying directly while collecting static data. In such instances, surveyors typically establish the base using single-point coordinates of the unknown point for RTK surveying, simultaneously starting static surveying on the base. Once static surveying concludes and known point coordinates are derived through post-processing, it's crucial to perform base grid shifts on all surveyed points within this period, ensuring all coordinates adhere to a unified reference. This is where the "Add Offsets to Points at Specified Period" function comes into play.
Function Introduction:
The "Add Offsets to Points at Specified Period" function does precisely what its name suggests: it adds base offsets to points surveyed over a specific period. Typically, this is to shift the base coordinates from unknown points to known points, ensuring relative unity of the project points.
Here's the main difference between "Add Offsets to Points at Specified Period" and the previously mentioned "Calibrate Point" method:
Calibrate Point applies the base offset to the point about to be surveyed but does not impact previously surveyed points. Points that have been saved in the point library before will not be subject to this offset.
This function is mainly used for large-scale projects where one base station cannot cover the entire area. When moving a base station to the next area, the new base station needs to be calibrated to be unified with previous points.
Add Offsets to Points at Specified Period offsets points that have already been surveyed without affecting those pending survey. You can see the base to which each surveyed point belongs. When offsetting a base or a point under this base, the same offset is applied to all points under that base. The applied offset is visible within this function and also in the point details. This process is repeatable; you can clear previous offsets and apply new ones.
The points surveyed under a base before and after using "Calibrate Point" are displayed as two distinct periods in "Add Offsets to Points at Specified Period" to distinguish them from each other. If you wish to eliminate this offset or apply it to earlier surveys, you have the flexibility to do so here.
Workflow of "Add Offsets to Points at Specified Period"
1. If the new known point is the base station point:
- Save the previous base coordinates to the point library in base information.
- Add known point coordinates to the point library.
- In this function, select the saved base coordinates as GNSS coordinates.
- Select the known point coordinates and apply the offset.
2. If the new known point is a measured point by the rover:
- Add the known point coordinates to the point library.
- In this function, select the GNSS point coordinates and the added known point coordinates.
- Apply the offset.
Both above functions are supported in SingularPad software, which is a powerful and versatile field surveying software for both GNSS devices and total stations. SingularXYZ team has put a lot of efforts into continuous research and development, enabling SingularPad to meet most of your requirements.
To learn more about SingularPad, visit:
https://www.singularxyz.com/SingularPad.html
