What is the definition of pos-assisted aerial triangulation?

Pos-assisted aerial triangulation is the theory, technology and method of installing the positioning and attitude system (pos) composed of GPS and IMU on the aerial photography platform, obtaining the spatial position and attitude information of the station at the time of exposure of the aerial photography instrument, and considering it as an observation value to be introduced into the leveling of the photogrammetric area network, adopting unified mathematical models and algorithms for determining the point position as a whole, and evaluating the quality of the point position. The airborne GPS and IMU are used to obtain pos information, which is used as a weighted observation value to assist the participation in the regional network leveling.

I. Purpose and significance of airborne triangulation purpose

Purpose:

Provide directional control points and image orientation parameters for surveying and mapping topographic maps.

To determine the uniform coordinates of boundary points over a large area.

Calculation of the coordinates of a large number of ground points in the unit model.

Resolving close-up photogrammetry and non-terrain photogrammetry.

Significance:

Determination of the position and geometry of a measured target without touching it.

Points can be quickly and simultaneously determined over a large area.

In order to save the field measurement workload, not limited by the visibility conditions.

Photogrammetric leveling with uniform accuracy within the area and not limited by the size of the area.

Second, the introduction of aerial triangulation

Aerial triangulation is a three-dimensional photogrammetric survey, according to a small number of field control points, indoor control points encrypted, encrypted points to obtain the elevation and the plane of the position of the measurement method. Its main purpose is to provide absolute directional control points for the lack of field control points in the area mapping. Aerial triangulation is generally divided into two types: analog aerial triangulation, i.e., optical-mechanical method of aerial triangulation; and analytical aerial triangulation, i.e., commonly known as computerized encryption. Analog air triangulation is in the all-purpose stereo measuring instruments (such as multiples) on the air triangulation. It is to recover the stereo model of the route on the instrument which is similar or corresponding to that of the photography, to select the encrypted points according to the need of mapping, and to determine its elevation and plane position. Aerial photogrammetry utilizes the inherent geometric properties of the image film to encrypt control points indoors. That is to say, the use of continuously taken aerial camera film with a certain degree of overlap, based on a small number of field control points, photogrammetric methods to establish the corresponding route model with the field or regional network model (optical or digital), so as to obtain the plane coordinates and elevation of the encrypted points. Mainly used for topographic maps.