International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B3. Istanbul 2004 International Archi
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collinear error function was adopted with the observational
values of extracted linear primitives and their corresponding
object space linear primitives (Zuxun Zhang 2003). In this
paper, a more simple error function is proposed based on the
generalized point photogrammetry, which unifies the point
primitives and linear primitives.
From mathematical all lines or curves are consists of points
(figure 4) and the collinear equation is commonly used the all
mathematical points. In this research, the affine transformation
mathematical model based on parallel ray projection was
adopted (equation 1), which is the strict in theory and the
parameter computation of remote sensing image with high
resolution based on it is very stable, namely the problem of the
relativity of image parameter calculation is solved completely
by the strict geometric model (Jianging Zhang 2002). For every
pair of image space line segment and object space point, only
one equation, depending on the direction of the line segment, is
used. When 6 is more than 45°dx can be served as the error,
otherwise when 6 is less than 45°dy can be served as the error.
The underlying principle in this mathematical model is that the
projected point of the object space line by the mathematical
model (green point) lies on the line segment extracted from the
image (Figure 4). If we have little GCPs the hybrid adjustment
can be done without any modification of the error conditional
equation, which can solve the problem of too little GCPs or
improper distributing and improve robustness and accuracy of
adjustment.
P
Figure 3: perspective geometry model between the image space
line segment and the object space feature point on
line segment
A ec Lay
Figure 4: geometry condition between the image space line
segment and the object space feature point on line
segment, green point is projected from
corresponding 3D line, the red point is extracted
feature point corresponding to 3D line
x=(a, ta, X+a,Y+ az) £78. when [2 > 45°
^ mcosa
(1)
y=b+bX+bY+bZ when —|0|« 45?
Where x and y are image space coordinate in pixel
X and Y are object space coordinate in meter
In term of least squares estimation, equation (1) can be
considered as a nonlinear observation equation. Applying
Taylor's series to equation (1), dropping second and higher
order terms, the linearized form of the observation equation
becomes
A, dx A, - da, * A, da, + À, da,
+4, da, +4,-da+F, =0
(2)
A-dy+ A, -db,+ A, -db + A, - db,
+ A, db, + F, Z0
4. RESULT
In this section, results of the approach proposed in this paper
are presented. We select three SPOT3 PAN images with 10 m
pixel ground resolution at south of Gansu province of China,
which belong to mountainous area. The topographic database of
river net is vectored from map with the scale of 1:50000. The
DEM data is obtained with the precision of 25m-grid space.
Because of the non-linearity of the system, the final solution is
obtained iteratively. The result indicated that the iteration
converges very fast. After each iteration of the adjustment the
weight of each observation is recomputed with the weight
function of Helmert method. Then the weights of the
observations containing gross errors will become smaller and
smaller until finally approach zero. Therefore, the result of
adjustment will not be affected by the blunders. Based on the
exterior orientation parameter, SPOT3 PAN Images are
superposed by the georeferenced Map with the scale of 1:50000
(figure 5). To quantitatively assess the accuracy of the exterior
orientation parameters computed above, 50 check points for
every image (ground object points and their corresponding
points on image) was tested (table 2). The three test area are all
belong to mountainous area with the elevation interval of
1000m above and slope grade of 20°above. The conclusion can
be drawn that the exterior orientation can satisfy the
requirement of map revision with the scale of 1:50000 based on
the criterion in table 2 (Remote sensing institute of Sichuan
province, 2002).
Model RMSE X- Y- Max Max
name RMSE RMSE X-err Y-err
257281 1.266 0.978 1.500 -1.929 3.471
256282 1.309 1.300 1.318 3.124 -3.036
258282 1.485 1.461 1.508 2.608 -2.651
Table 1: Experiment Results Of Exterior Orientation with
Check Points (Unit: Pixel)
Type of Characteristic RMSE | Max Error
region
Plain or elevation interval 600m | 20m 2 times of
Hill grade 71 6° RMSE
Mountain | elevation interval 2600m 30m 2 times of
grade 2 6° RMSE
Table 2: Precision of Check Points for Map Revision with Scale
of 1:50000
Figure 5: . SPOT
Georefer
paramet
This paper introdi
exterior orientation
resolution by matcl
image against the c
river map or a GI
based on automatic
sensing imagery ar
result shows that
requirement of maj
presented procedure
therefore has the p
workflow. Propose
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Thanks for the sup;
China (No. 403370:
Ackermann,F. 1984
and potential applic
record, 11(64): 429.
Burns, J. B., A.R. E
straight lines, IEE
Intelligence, Vol. 8,
Doucette, P., P. Ag
Self-organised clu:
imagery, ISPRS |
Sensing, 55(2001):3
Gruen, A., P. Agour
With dynamic progr