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Other airborne POS applications include gravimetry and 
gradiometry, laser bathymetry and stabilized sensor 
platforms. 
7. OTHER POS APPLICATIONS 
Road Survey Vans: POS/LV, (POS for Land Vehicles), was 
developed to measure vehicle motion dynamics for the 
purpose of computing road inspection parameters such as the 
transverse slope of the road (crossfall), and the longitudinal 
profile of the road. Measurements of crossfall provide useful 
information such as the bank of the road during curves, as 
well as whether the road is properly sloped for drainage 
purposes. Longitudinal profile is the vertical variation of the 
road with respect to the local level, for wavelengths of up to 
200 m. Such information is useful for evaluating road 
roughness which effects ride quality. In addition to GPS, 
POS/LV integrates measurements from a Distance 
Measurement Indicator (DMI) subsystem. The DMI provides 
accurate distance travelled and velocity measurements, which 
complement the aiding information from the GPS. This 
additional information increases the accuracy of the blended 
attitude solution to better than 2 arc-min RMS for roll and 
pitch. 
Track Geometry Cars: POS/TG (POS for Track Geometry) is 
quite similar to the /LV application. The IMU is mounted on 
the axle of a car to measure various types of deformation of 
the railway tracks. A DMI and GPS are used as the aiding 
sensors. 
Hydrographic Survey Applications: POS for Marine Vehicles 
(POS/MV). Motion compensation of multibeam sonars for 
quantitative hydrographic survey can take one of two forms. 
The returned echoes from the sea floor received on multiple 
acoustic beams fixed in the ship's reference frame are 
dynamically corrected for ship orientation relative to the 
geographic reference frame at the instant the bottom echo 
from each beam is detected. Alternatively, the multibeam 
sonar continuously "steers" its beam array so as to decouple 
the beam array orientation from the roll and pitch of the 
ship. In both cases, ship roll, pitch and heave data are 
required from a motion sensor that ideally monitors the 
motion of the sonar transducer directly. Typically the 
motion sensor is located near the sonar transducer on the 
assumption that the relative motion between the transducer 
and motion sensor is negligible. 
8.0 ACKNOWLEDGEMENTS 
The authors wish to thank the following organizations and 
individuals for their various forms of support: Mr. Bob 
Glanfield of NRC Canada, Mr. Robert Charpentier of DREV, 
and Dr. Jack Gibson, of Canada Centre for Remote Sensing. 
9.0 REFERENCES 
[1] C.D.Anger, S. Mah, S.K.Babaey, Technological 
Enhancements to the Compact Airborne 
Spectrographic Imager (casi) Ist International 
Airborne Remote Sensing Conference and 
Exhibition, Strasbourg, France, September 1994. 
[2] W. Gesing and D.B. Reid, An integrated multisensor 
aircraft track recovery system for remote sensing, 
IEEE Transactions on Automatic Control, Vol AC-28, 
March 1983. 
[3] 
[4] 
471 
J.R.Gibson, 
Photogrammetric Calibration of a 
Digital Electro-Optical Stereo Imaging System, 
GEOMATICA, Vol. 48, No. 2, Spring 1994, pp. 95- 
169: 
Mary Jo Wagner, Seeing in 3-D Without the Glasses, 
Earth Observation Magazine, July 1995, pp. 51-53. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B3. Vienna 1996