at reasonable expences, concerning equipment and staff.
METHODS
The demands for accuracy with a minimum of ground control, makes it neces-
sary to use metric cameras. The test measurements are performed using wide
angle and super wide angle cameras of type WILD P31.
The various shapes of the objects and narrow enviroments at shipyards, often
require a great freedom concerning positions and directions of photography.
Thus, the system should not put any restrictions upon camera orientation.
Multistation photography is supposed to give the best accuracy, and is there-
fore recommended.
The images are digitized in monocomparator. In most cases a traditional ste-
reo-autograph will be inconvenient, due to limitations in depth of the object,
and orientation angles. If an analytical plotter is available, several con-
trol tasks may preferably be solved with this instrument. This applies for
example to straightness or smoothness of lines and surfaces. However, the
developed system could not be based on this equipment, because of its high
cost. There are also restrictions on convergence of photographs, due to dif-
ficulties with stereoscopic view.
Object co-ordinates are computed by bundle adjustment. An existing computer
program for bundle adjustment of aerial photography has been modified and
used. For the implementation on a shipyard, a tailor-made version will be
implemented on a smaller computer.
To obtain ground control has often been a time-consuming job. To meet the
demands on time consumption, a ground control network has to be established
around the areas where structures are built. The points should be permanent-
ly targetted, or prepared for quick targetting when required.
It may be difficult to establish a satisfactory three-dimensional network
of control points, especially at out-door sites. Therefore the computer
program must contain possibilities for using auxiliary control data, such
as distances between points, points lying on a plumbline or in a plane, etc.
Since the image digitizing is carried out in a monocomparator, each point
of interest has to be carefully targetted. Each point should be imaged in
at least three pictures. This will improve both the precision and the gross
error detection. To ensure correct identification, the targets should be
accompanied by identification codes.
The described system contains detailed descriptions for each task during a
measurement project. These procedure descriptions contain quide-lines for
decision-making during planning, and check-lists for operations. This will
save time and work during a project, and enable the transfer of tasks to
operators without high knowledge of photogrammetry, which is in the interest
of the shipyard's control department.
COMPUTER PROGRAMS
In addition to the procedure descriptions mentioned above, the FOMAKON sy-
stem contains a collection of computer programs. This program system hand-
les the data from the digitizing of pictures through the presentation of
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