1d leads to: 
(4-1) 
oint is equal 
the attitude 
is the same, 
vo corrected 
le inspected 
rence plane 
parameters 
ected image 
n be simply 
d and nadir 
NN 
terrain 
EM (| 
ected image 
ditional part 
> result (4-2) 
(4-4) 
  
Figure 8 Produced DEM 
  
Figure 9 DEM with the corrected nadir image 
6. REAL TIME STEREO PROCESSING 
The use of very precise measuring instruments for the 
determination of flight location and position makes possi- 
ble an on-line stereo processing of data instead of the 
expensive procedures of the conventional photogramme- 
try. All iteration procedures can be changed by straightfor- 
ward-algorithms. The matching algorithm must be 
replaced by an on-line procedure, where a ray tracer with 
attitude information gives the start information for related 
pixels between different image strips, and a fast correlation 
algorithm finds conjugated points. It is necessary to find a 
compromise between the accuracy of the information and 
the number of calculated points. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B3. Vienna 1996 
Applications for the on-line procedure could be change 
detection (after disasters like earthquakes) or map updat- 
ing (e.g. for telecommunication). 
7. CONCLUSION 
The Wide-Angle Optoelectronic Stereo Scanner (WAOSS) 
built for the Mars-96 orbiter was used on board aero- 
planes. Direct and accurate measurement of attitude 
parameters (roll, yaw, pitch, ground speed and altitude 
variation) gives the parameters of exterior orientation for 
each measured CCD-line. The high accuracy of angle 
determination is strongly related to stochastic drift. The 
future work is focused on the on-line drift correction and 
precise determination of angle offset. 
Using attitude and camera calibration data CCD-line scan- 
ner data can be geometrically corrected. If these image 
strips are processed on the same mean flight path, the 
correction procedure is equivalent to the conventional inte- 
rior and exterior orientation and gives epipolar-like images. 
The geometrically corrected images are a necessary pre- 
processed data product for further 3-D processing and 
allow also a coordinate measurement with a photogram- 
metric workstation, for example, and the generation of dig- 
ital elevation models (DEM). 
The independence from additional GCPs and straightfor- 
ward algorithms makes an on-line approach for DEM gen- 
eration or DEM improvement on board the aircraft possible 
without human action. 
8. LITERATURE 
[1]D.Oertel, R.Reulke, R.Sandau, M.Scheele, T.Terzibas- 
chian, A Flexible Digital Wide-Angle Optoelectronic 
Stereo Scanner, International Archives of Photogram- 
metry and Remote Sensing, Vol. XXIX, Part B1, Com- 
mission I, 1992, pp. 44 
[2]M.Scheele, T.Terzibaschian, Attitude and positioning 
measurement system used in the airborne testing of 
the original Mars Mission Wide-Angle Optoelectronic 
Stereo Scanner WAOSS, International Archives of 
Photogrammetry and Remote Sensing, Vol. 30, Part 1, 
1994, pp. 47 
[3]M.Lehner, R.Gill, Photogrammetrical Adjustment of Tri- 
ple Stereoscopic Imagery of an Airborne CCD scanner, 
Optical 3-D Measurement Techniques, edited by 
A.Grün/H.Kahmen, pp.123, Karlsruhe 1989 
[4]A.Borner, Simulation  optoelektronischer Systeme, 
Diplomarbeit TU Ilmenau, 1995 
[5]Timm Ohlhof, Lokale, regionale und globale Punktbes- 
timmung mit Dreizeilenbilddaten und Bahninformation 
der Mars 96-Mission, Dissertation, München 1996