Different algorithms are used in the different engines and different error estimates are produced. RTK and VRS vectors get theirs from the engine in the receiver. Post Processed vectors get their error estimates from the TBC processing engine. Q: How does network adjustment handle static GNSS, VRS, and RTK data?Ī: Usually you would want to use the Baseline Processor’s error estimates for GNSS data. The Reference Factor will tell you if the estimates from the field data need to be scaled. If you choose to use Imported Files as your source for error estimates, you do not need to enter an estimated value. That allows for a bit of leeway in deciding what estimate you wish to input in the setting field. In the end, the product of the input error estimate and the scalar for that observation type is what is used. Q: If you use the mean angles from multiple sets of terrestrial angles, do you need to adjust your weighting estimates for your horizontal angles?Ī: If you choose to use the Project Settings as the source for your error estimates, You can enter what you think is a reasonable estimate for your horizontal angles there and the Horizontal Angle Reference Factor will tell you whether you have guessed correctly or not. Is there a way to get all the HZ grouped together separated from V and slope D (and the same with V angles and Slope D) so that we end up with 3 lists of observations and residuals, sorted by residualĪ: You can customize the network adjustment report in order to split the table into three. Q: In the network adjustment report, the residuals (unreduced), are presented per shot (HZ, V, Slope D grouped together). Q: Is there any paper going into depth about the GNSS baseline processing in TBC available, linear combinations used etc?Ī: Here is a white paper you could visit: Modernized Approaches for GNSS Baseline Processing White Paper. It is possible that we could add this information to TBC but it is rarely requested. Oftentimes they have a scientific model that includes the deflection of the vertical information for an input position. It probably would be best to go to the source of the geoid model to obtain that information. Can you comment on this idea and explain why TBC does not provide this option?Ī: Deflection of the vertical is a function of the geoid model to ellipsoid relationship. Q: Some third party adjustment packages include the ability to model the Deflection of the Vertical. They both put parameters into the Coordinate System definition but those parameters do slightly different things to the GNSS vectors in the project. As explained in the webinar, the two types of adjustments work in different ways and are in large part incompatible. Q: Are you able to do a Network Adjustment and a Site Calibration in the same project? If not, why?Ī: No. Q: How do you set the error tolerances for your fixed control points or benchmarks?Ī: The most common approach is to use the default 0.000 constrained value, but you can set it as below. If your vertical datum is not tilted much compared to the satellite datum then this may be acceptable. This will result in elevations for the unknown points that aren’t really in the vertical datum as well. If the Deflections are turned off and you fix more than one point vertically then your network will have to be distorted to make the constraints work. They are still tilted to agree with the satellite datum. Note that your GNSS vectors are not providing vertical values for the unfixed points that agree with the vertical datum in the area if you do not fix three elevations and allow the tilts to happen.
So fixing one point will provide a vertical shift only, even if the Latitude and Longitude Deflections are turned on in your Adjustment Settings. It cannot calculate the tilt parameters until you lock more than one. Q: Is there a method to adjust the network vertically moving the entire dataset up and down to best fit the 3 vertical points instead of putting a tilt across it?Ī: It will effectively move the network up and down if you constrain only one point vertically.
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