The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B3h. Beijing 2008
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goal of these two matches are the same from the aspects of
image processing. During the process of object-side 3D feature
point’s correspondence, both stereo-sequence match and
sequence-stereo match can be applied. However, the different
matching order will has different matching effect to the final
moving object-side 3D feature point correspondence. In actual
operation, the adjacent images took by one camera are similar,
because the time interval between two adjacent images is very
short. Thus, the sequence image match from same camera is
easy, but because its base line between viewpoints is relatively
short, 3D reconstruction is difficult. Therefore, the estimated
depth is not precise in the situation when noise exists (it is even
impossible when baseline is fairly short). With this
correspondence, there is usually a certain baseline between
different cameras, the object-side 3D reconstruction precision is
fairly high among stereovision because the distance between
viewpoints is large, but stereo matching is difficult, especially
when huge disparity and image distortion exist. The double
match restraint namely first extracts random feature points on
moving objects from different-time but same-sequence images,
determining the corresponding relationship of feature points
among the same sequence images, establish the sequence match
of binocular image sequences. If the image sequence sample
density is appropriate, the reliability of the feature match in
sequence image can be guaranteed. Then according to match
corresponding point coordinates which obtained from the
sequence match result matching with corresponding images of
same-time different sequence (left and right images stereo
match). Therefore, the difficulty of random stereo match can be
decreased to a great level through this double match restraint.
As a result, the whole correspondence of moving object random
three-dimensional feature points can be obtained preferably.
The process of double matching restriction as figure 2 shows.
The left and right images at time /,■ are denoted by /, and A
corresponds point in images plane 7, and /’, are denoted by m,
and m The point Mi in 3D space expressed in the coordinate
system attached to m, and m 7? u+1 ,6, +1 is the rotation matrix
and the translation vector describing movement object from at
time ti to t i+l .R LR ,,t LR is the rotation matrix and the translation
vector between the left and the right camera. The images
matching between points m, and m ) is stereo matching, while
the images matching between points m, and m, +1 (or between
points m and m +1 ) is motion matching. The correspondences
between points Mi and M i+X are features correspondences. Here
/=3.
Figure2 motion-stereo double matching restriction
confirming corresponding connection of feature points in
sequence image and finishing move matching of double
sequence image. As long as sampling consistency of sequence
image is suitable, we can obtain the credible feature matching
of moving sequence image; Secondly, carry on stereo matching
between different sequence images and the corresponding
feature point is searched on the other image for matching
according to the preceding match result (coordinates). In order
to advance calculation speed and matching precision, the
strategy which examine the dynamic moving object, and limit
the matched object on moving object is used before moving
matching (screen the static background of moving object).
3. EXPERIMENTAL RESULTS OF REAL DATA
Using the established binocular stereo vision system in doors
for this research, obtains binocular sequence motion images of
model car in a certain way to move (as figure3). According the
request of 3D movement object’s location and tacking, the
feature point’s correspondence of movement object is
performed by motion-stereo double matching restriction of
binocular sequence image. Combining the results of the camera
calibration, using the triangulation process for reconstruction
feature points of moving object 3D coordinate from binocular
sequence images, the method guarantees the correspondence of
arbitrary object-side feature point of the move object at
different time. The concrete steps as follows:
Figure3. Binocular vision system
(T)Doing motion matching for movement object binocular
sequence images can obtain motion matching result which in
the same sequence at time t x and t 2 (as figured).The coordinate
matching file as table 1. Where X, Y and X', Y' is the matching
coordinate of the same feature point at time /j and t 2
respectively.
Figure4 Same sequence motion matching at time /[ and t 2
In order to finish double matching restriction, firstly the feature
points are extracted from moving images at different the time
(front and rear) simultaneously, and original matching table is
created between the features of two images, the possible
candidate match points of a feature are found in the other image.
Based on the above matching methods and some hypothesizes,
considering compatibility of feature matching in a certain range,
finding out the best feature as the final matching result,
Pixel
X
Y
X'
Y'
1
129.0
150.0
139.0
151.0
2
133.0
152.0
143.0
153.0
3
127.0
153.0
137.0
154.0
4
160.0
126.0
170.0
127.0
5
157.0
126.0
167.0
127.0
6
180.0
136.0
190.0
137.0
7
153.0
149.0
163.0
150.0