The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part Bl. Beijing 2008
The error equations for parallax ( Ax , Ay ) at point 1 from
camera A and C is:
Vi ac (•*■) = AAx ~ ACx + (/ + - (/ + ~J-) A <P C +
“ A ®c + * y C hK c - ^ac
v \ac O') = ~ AC y + ~J ± A( Pa ~ A(p c + (/ + y
2 0)
-If + y ) A ® C + x a Ak a - x c A K c - Ay AC
where, Ax ac , Ay AC are the parallax observation values obtained
by least square matching of images from A and C; AAx , aAy,
ACx , ACy are the deviation values of the optical centre of A and
C; x A ,y 4 , x c ,y c are the image coordinates of point 1 projected
from A and C; f is the principle distance of the cameras; a<p A ,
Aco A , Ak a and a<p c , Aa> c , Ay are the errors of q>, co , k of A
and C need to be collected.
The error equations for point 2, 3...12 with other overlapping
structure from B-C, A-D, B-D and A-B can be derived similarly.
The following condition equations are accepted
<Pa + <Pb=°
0) c + CO D = 0 (2)
Ka+K b +K c +Kd= 0
From the equation (1) and (2),
the A(p A , Aco a , ak 4 , A<p D , Aco D , Ak d can be solved. Thusly,
the deformed errors due to the light and simple constructed
mechanical frame can be compensated. The remained error is
less than 0.4 pixels. This method is important for reducing the
weight of sensor system making possibility to be accepted by
UAV mapping.
Figure 8a, b, c, d and figure 9 show the images taking from
camera A, B, C, D and the equivalent image constructed by
above mentioned method.
4. PHOTRGRAMMETRIC PROCESSING
4.1 Aerial Triangulation
According to the feature of data get from the UAV acquisition
system, a special aerial triangulation program has been
developed. The advantage features of this software are as
follow: 1) Making high precision calibration for the geometric
distortion from normal purpose used digital cameral. 2) Using
Pos or GPS data combined with image matching to reconstruct
the topologie relation of the images along the flying direction
and between the neighbouring lines. 3) All the points in the
triangulation network are selected and measured fully
automatically (Figure 10.). 4) multi-view geometric relations of
the images are solved by large block adjustment with least
square method (Figurei 1.). 5) The coarse error are detected full
automatically by large number of redundant observations. 6)
The result of orientation elements and control points are
calculated through alternative solution to achieve 1:2000,
1:1000 or 1:500 scale mapping standard.
£3 u t MM •■■■■■& 3.
FigurelO. select and measure the observed points fully
automatically
Figureil. multi-view geometric relations of the images
4.2 DEM Production
After aerial triangulation the multi-view images are reorganized
to be divided automatically into basic units as the stereo pairs in
traditional photogrammetry. Then the DSM is automatically
generated by image matching and TIN interpolation within
every unit. It need a little manual interaction operation to
separate the points upon the building or lie down at grand for
generation DEM. ALL units are link up to form fully coverage
DEM (Figure 12.).
4.3 DOM Production
The DOM is also produced automatically based on the
orientation elements and DEM results. Because 80 percent
overlapping along flying direction have acquired from aerial-
photography, only the centre part of image in the frame have
been taken to be rectified into orthophoto imagery(Figurel3.).
Figure9. the equivalent image of above 4 images