The plate coordinates with the stereoviewer are updated from the ground
coordinates fifty times per second, using a rigorous perspective
projection together with corrections for lens distortion, earth
curvature and calibration constants.
2.3 SOLUTION TO ORIENTATION
The camera orientation is computed by a rigorous bundle solution which
can include a variety of parameters as control. As well as being able
to use coordinates of specific points, it can use the distance between
points or the direction between points (bearing) as additional
information. This means that a model can be set up by observing an
object of known dimensions such as a survey staff.
The results of the bundle are stored in the job file and are transmitted
to the stereoviewer. This means that the model can be re-setup at a
later date by simply measuring the fiducials (interior orientation).
2.4 SELF CALIBRATION FOR NON METRIC CAMERAS
For non-metric cameras the instantaneous focal length at the time of
exposure can be calculated automatically provided sufficient control is
available.
2.5 LENS DISTORTION
Aliowance is made for both symmetric and assymetric distortion using
constants derived from the lens calibration program. A polynomial is
used to compute a set of corrections at selected positions on the
photograph. As the system operates these corrections are included.
3.0 FACILITIES FOR TESTING THE SYSTEM
Accuracy and repeatability of the MPS measuring system and its operation
in Orientationand Digitising modes can be checked with special grid
plates provided with the MPS. These plates are engraved with
calibration grids, pseudo-camera fiducials, and a pattern of simulated
ground control, to an overall accuracy of better than one micron.
Systematic errors and non-linearities are removed from the basic XL, YL,
XR, YR measuring system by a calibration progran.
4.0 HOST COMPUTER SOFTWARE
MPS System Flowchart
Model Specification
CREATE JOB FILE Lens Specification
(MPS10) Camera Specification
Photographdata (optional)
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