Bundle block adjustment
The term bundle block adjustment or bundle adjustment comes from photogrammetry and refers to the optimization of the "visual rays" of a 3D scene that is recorded by several cameras or by one camera from several perspectives. With the bundle block adjustment, the positions of the points in 3D space, the positions and orientations of the observing cameras and their internal calibration parameters can be adjusted to the measurement images in such a way that remaining errors (e.g. image distortions, measurement errors in the evaluation) are optimally applied to all Observations are distributed.
In particular, the term is used to photogrammetrically evaluate not only individual image pairs (2 overlapping measurement images each), but to link any number of connected images (block) with one another.
It does not matter whether such an image block represents a contiguous area of the earth's surface ( aerial photogrammetry ) or any object of close-range photogrammetry recorded from several terrestrial viewpoints.
One speaks of a bundle , since each pixel of a measurement image defines a ray through the projection center (camera lens) and all pixels measured in an image are therefore bundled into a bundle in the projection center ( central projection ).
The linking of the images is achieved with the help of corresponding points, which can be recognized in several overlapping images and which can each be precisely localized. This process is called aerotriangulation (also: image triangulation), with the help of which an area can be bridged without control points . The selection of these points can also be made or supported by automatic algorithms for pattern recognition .
A system of equations is used for the calculation , which mathematically maps the beam path shown above. Since there are significantly more observations (measurements) than unknowns, the errors in the measured image coordinates are minimized with the help of the adjustment calculation.
As a result of the adjustment calculation, the unknown orientation elements ( outer and inner orientation ) of all images and, in addition, the previously unknown object coordinates of all connection points are obtained at the same time . The more of these points are included in the bundle block adjustment in as many different images as possible, the more precise the subsequent adjustment calculation will be.
Following a successful bundle block adjustment, you can continue with the conventional photogrammetric evaluations and record any other objects in three dimensions .
See also
- Analytical photogrammetry , block triangulation , orthophoto
- Sebastian Finsterwalder , Armin Grün , Gottfried Otepka , Hellmut Schmid
literature
- Karl Kraus : Photogrammetry (7th edition) Volumes 1 and 2, de Gruyter, Berlin 2004.