How to convert coordinates and elevations in railway survey using airborne lidar measurement technology

Jun 01, 2023

The airborne lidar measurement technology combined with GPS differential technology can quickly obtain the three-dimensional coordinates of ground objects. Of course, the coordinate system of most railway project exploration at this stage uses the national coordinate system or local coordinate system.

In view of the fact that the geodetic elevation based on the elliptical surface provided by the airborne lidar measurement technology in actual work cannot meet the normal elevation problem of the geoid as the reference in the railway project survey, the coordinates and elevation conversion of the positioning results are moderately carried out. for more precise positioning.

For example, a ground reference line can be set every 50 km on the ground, and the ground reference station can be constructed by using the conversion parameter control points in the national coordinate system or local coordinate system. Not only that, but it can also fully combine the GPS baseline vector network to obtain the constrained adjustment of the data, further obtain the conversion parameters, and then perform coordinate conversion after the conversion parameters.

Under normal circumstances, there will be three-parameter conversion, so two control points must be applied at this time. Based on this, the application of airborne lidar measurement technology can play the unique function of solving the conversion parameters of this technology. Elevation conversion is actually aimed at the elevation anomaly model of the geodetic height control that is made synchronously for the data point elevation anomaly existing in the airborne lidar measurement technology, moderately integrates the anomaly changes in different regions, and appropriately increases the control points The specific density value should be combined with the level change.