Henrik Haggrén
Implementation Issues for Orientation Algorithms
The paper deals with implementation issues for orientation algorithms as it regards digital
photogrammetric systems. The general application of these systems is the 3-D digitizing of objects and
space. The instrumentation used for the applications is generally any video recording system. The output
of the procedure is expected to be a geometric 3-D model including. The systems are assumed to be half
automatic with clear human interaction.
In the paper, first the definitions of coordinate systems, datums and orientations are discussed as it regards
the measuring procedures. The measuring procedures were then analyzed and described as graphical
process models. The graphs of tree application/instrumentation combinations are attached to this
document
1. Reverse Engineering / Video Profilometer.
2. Photorealistic Buildings / Still Video
3. Plants and Facilities / VCR Video
I all these models the relevant process flow is shown in bold with respect to the application in question.
Coordinate Systems
Image. The image coordinate system is the one in which the image will be recorded. It is two-
dimensional and presumed to be a plane. As it regards digitized images, the datum relates to the CCD
array of the imager chip, to the frame grabber clock, or to the film digitizer geometry.
Camera. The camera coordinate system is three-dimensional with its origin in the perspective Centre.
The datum relates to the image plane parallel to two of the coordinate axes and is determined by
coordinates of the fiducial marks and the camera constant.
Stereo. The stereo model is a result of a relative orientation between two images or between two camera
coordinate systems. The coordinate system is three-dimensional. Its origin is usually first defined to be one
of the perspective centers. The primary coordinate axis is aligned by the second perspective Centre,
whereas the secondary axes coincide with the principal horizontal and principal vertical.
Object. The object model is a result of several images, camera coordinate systems, or stereo models
transformed to a common coordinate system. Unless the object coordinates are transformed to a local
world coordinate system, a principal datum can be defined by any other 3-D coordinate system, e.g. one of
the stereo model coordinate systems.
Design. The design model is either analog or digital model of an object. It may be e.g. a clay model or a
CAD model. In such cases the datum is fictitious and relates to geometric entities, like planes, rotation
axes, their intersections, etc. The coordinate systems are three-dimensional and can vary upon functional
definition from traditional rectangular systems to parametric ones.
World. The world coordinate system is any local or global system to be finally referred by the above
mentioned other coordinate systems. The world coordinate system is usually monumented by control
points for local referencing.
Haggrén -1
