Why is gps measurement less accurate than leveling?

Because the water level conditions required for GPS measurement are higher when measuring, and level measurement requires that the water level is not high, so the accuracy of the measurement is lower than that of level;

When using GPS measurement technology to indirectly determine the normal height of the ground point, the heights of all the GPS points in the measurement area are directly measured, and then the number and location in the measurement area that can satisfy the required elevation fitting are selected of several GPS points.

The normal height is measured by the water level measurement method and the difference between the heights of all GPS points and the normal height (elevation anomaly) is calculated. Plane- or surface-fitting based methods can fit the altitude to obtain the measurement area. Normal altitude of other GPS points in the interior.

The biggest advantage of GPS altitude measurement over traditional methods of measuring levels is that it is not limited by distance.

Expanded Information

GPS elevation application:

1, GPS is used for third level, fourth level encryption

Leveling adjustment in mountainous and hilly areas, the workload is large, GPS leveling can be used for the third and fourth level encryption.

2. GPS cross river leveling

Using GPS relative positioning, across a large distance, high accuracy. If existing national standard points on the bank are used, reasonable levels are chosen to form the GPS leveling network and GPS geodetic elevations can be converted to normal elevations using curve or surface fitting methods. Accuracy is fully guaranteed, while triangular elevation is difficult to realize.

3, GPS level for deformation monitoring

GPS measurement is widely used for monitoring crustal deformation and ocean surface changes due to its high speed, high accuracy, unobservable conditions and edge length limitations. For direct measurement of three-dimensional deformation, the layout can be extended to a relatively stable area to establish a reliable stability datum for deformation analysis.

Reference:

Baidu Encyclopedia-Plane Control Measurement

Reference:

Baidu Encyclopedia-Elevation Measurement