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Rendering three-dimensional information of a scene from optical measurement is very important for a
wide variety of applications such as robot navigation, rapid prototyping, medical imaging, industrial
inspection, etc. In this paper, a new 3D measurement method based on mesh candidate with structured
light illuminating is proposed. The vision sensor consists of two CCD cameras and a DLP projector.
The measurement system combines the technology of binocular stereo vision and structured light, so as
to simplify the process of acquiring depth information using mesh candidates. The measurement
method is based on mesh candidates which represent the potential depth in the three dimensional scene.
First the mesh grid was created along the direction of axes in world coordinate system, and the nodes
were considered as depth candidates on the surface of object. Then each group of the mesh nodes
varying along z axis were mapped to the captured image planes of both cameras. At last, according to
the similarity measure of the corresponding pixel pairs, the depth of the object surface can be obtained.
The matching process is between the pixels in both camera planes corresponding to the spatial mesh
candidates. Aided by the structured light pattern, the accuracy of measurement system improved.
Appending the periodic sawtooth pattern on the scene by structured light made measurement easier,
while the computational cost did not increased since the projector had no need to be calibrated. The
3DS MAX and Matlab software were used to simulate measurement system and reconstruct the surface
of the object. After the positioned cameras have been calibrated using Matlab calibration toolbox, the
projector is used to project structured light pattern on the scene. Indicated by experimental results, the
mesh-candidate-based method is obviously superior in computation and accuracy. Compared with
traditional methods based on image matching, our method has several advantages: (1) the complex
feature extraction process is no longer needed; (2) the epipolar constraint is replaced by mesh
candidates so as to simplify stereo match process; (3) the candidate selection strategy makes
unnecessary the process of transformation from two dimensional coordinates to three dimensional
coordinates.
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