What is the definition of pos-assisted aerial triangulation?

Pos-assisted aerial triangulation is a theory, technology and method that a positioning and attitude determination system (pos) composed of gps and imu is installed on the aerial photography platform to obtain the spatial position and attitude information of the camera station at the exposure time of the aerial photography instrument, and introduce it into the adjustment of the photogrammetry area network as an observation value, and determine the point position and evaluate its quality by using a unified mathematical model and algorithm. Pos information is obtained by airborne GPS and IMU as weighted observation to assist regional network adjustment.

First, the purpose and significance of aerial triangulation

Purpose:

Provide azimuth control points and photo azimuth parameters for mapping topographic maps.

Determine the unified coordinates of boundary points in a large range.

Calculation of coordinates of a large number of ground points in element model.

Analysis of close-range photogrammetry and non-terrain photogrammetry.

Meaning:

The position and geometry of the measured object can be determined without touching the object.

It can measure the position of points quickly and simultaneously in a large range.

So as to save the workload of field measurement and not be limited by visibility conditions.

In photogrammetry adjustment, the accuracy in the region is consistent and is not limited by the size of the region.

Second, the introduction of aerial triangulation

Aerial triangulation is a survey method that encrypts control points indoors according to a small number of field control points in stereo photogrammetry, and obtains the elevation and plane position of the encrypted points. Its main purpose is to provide absolute direction control points for regional mapping lacking field control points. Aerial triangulation is generally divided into two types: analog aerial triangulation, that is, optical mechanical aerial triangulation; Analysis of aerial triangulation, commonly known as computer encryption. Analog aerial triangulation is carried out on an omni-directional stereo measuring instrument (such as a multiplier). It is to restore the three-dimensional model of the route similar to or corresponding to photography on the instrument, select the encryption point according to the needs of surveying and mapping, and determine its elevation and plane position. In aerial photogrammetry, the method of indoor encryption control points is based on the inherent geometric characteristics of photos. That is, using continuous aerial photographs with certain overlap, according to a small number of field control points, the corresponding route model or regional network model (optical or digital) in the field is established through photogrammetry, so as to obtain the plane coordinates and elevation of the encrypted points. Mainly used for topographic mapping.