MOTION—STEREO DOUBLE MATCHING
RESTRICTION IN 3D MOVEMENT ANALYSIS
ZHANG Chun-sen
Dept of Survey, Xi’an University of Science and Technology, No.58 Yantazhonglu, Xi’an 710054,China
-zhchunsen@yahoo.com.cn
Commission III
KEY WORDS: Image matching, Stereo-motion, Sequence image, 3D reconstruction, 3D motion analysis
ABSTRACT:
In order to realize the correspondence of arbitrariness object-side feature points of movement object in the different time in 3D
motion analysis based on binocular sequence images, Aiming at the fact that motion and stereo matching exists simultaneously,
motion and stereo matching of images in the process is studied. The algorithm of double restriction matching combining motion and
stereo image matching is presented. The basic image matching based on point feature is completed by correlation coefficients and
relaxation algorithm, and 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. And using these object-side sequence
“image” (coordinate) accomplishes 3-D object tracking location. A set of experimental results of real data are presented, it shows
that the accuracy of the final correspondence is about 76.5%,which can meet the requirements of the 3D motion object tracking
location based on point feature.
1. INTRODUCTION
The problems of 3D (three-dimension) motion estimation from
visual data are among the most challenging problems in
computer vision. The way of 3D motion estimation includes the
method of monocular sequence image and stereo (or binocular)
sequence image, but there are distinctions in the complexity of
computing and accuracy of computing result. When monocular
sequence image estimation is being used, only relative moving
information can be gotten, and it’s exist a scale factor related to
the structure information. In order to get the structure
information, the traditional approach is having the aid of the
equipment of range finder. But it is difficulty to integrate the
different equipment or eliminate the system error. This paper
presents an approach of integrating the two cues of motion and
stereo when two cameras that takes pictures of moving object
repeatedly. Multi-ocular cues or binocular sequence images
approach, compared with single sequence images, not only the
computation is simple, but also the absolute translation in space
(structure information) can be acquired. But it requires solutions
of these sub-problems: the images matching problem, referred
to stereo matching in different sequence which at the same time
and motion (sequence) matching in same sequence which at the
different time, the reconstruction problem, in which 3D
information is to be reconstructed from the correspondences,
and the features correspondence problem, referred to different
time correspondence of feature points in object side sequence
“image”. All of these are the most important and difficult things
in computer vision.
Aiming at the fact that motion and stereo matching exists
simultaneously in 3D movement estimation based on binocular
sequence images, the author studies the motion and stereo
matching of images in the process. The algorithm of double
matching restriction combining motion and stereo image
matching is presented. Matching of images based on point
feature is completed by correlation coefficients and relaxation
algorithm. 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. And using these object-side sequence “image”
(coordinate) accomplishes 3-D object tracking. An experimental
result of real data by means of this algorithm is presented in the
article. The result indicates that the accuracy of the final
correspondence is about 76.5%. It can satisfy the 3D motion
object tracking location based on point feature.
2. DOUBLE MATCHING RESTRICTION
2.1 Object feature points extracting and initial matching
Extracting feature points from image is the first step of feature
image matching. This paper uses Harris operator to extract
arbitrariness feature points on sequence image. The experiment
shows that this operator is simple, stable, and insensitive to
noise, illumination and so on. It can also extract as ration. And
the distribution of feature points extracted is rational. The aim
of initial matching is gotten a matching candidate set T. The
correlation coefficient method is used in this paper [2] . Namely,
for each feature point which m, G image a, m 2 G image b. Their
image coordinates are supposed to be (wi,vi), (w 2 ,v 2 ).If the
difference between the coordinate of nq and the coordinate of
m 2 dose not exceed a certain threshold, calculates correlation
coefficient of (2n+l)x(2n+l) window which is irq, m 2 as centre.
A pair of points is presented, if they are considered as matching
points candidate, the correlation coefficient must be greater
than a certain threshold. The matching candidate relation
between a certain feature point in image and some feature