Errors reducing method of Laser 3 D scanner •

This paper presents the factors that influence the form scanning processing by using the laser: light ambient, scanning surface, motion axial, focal length of the camera. This paper will present the method to reduce the error of the environment by using the camera calibration algorithms and the coordinate movements. This errors reducing method to solve the problem from local to genera: from solving errors created by the curve of the cameras to the laser-line width, to the dark gray threshold of the images by the camera aperture and coupling 2movement axis to scanning-coupling more effectively.


GENERAL INTRODUCTION
3D Laser Scanner is a combination of a moving axis and a scanning ray.Therefore, if there is not a good coordination, the asynchrony will appear and cause errors.In addition, when the laser ray is projected on the surface will cause reflections effective.If it is not handled, we will not be able to scan objects.CCD camera has certain flatness in the work area; we need to flatten the whole surface, to avoid focal curves generated by the focal distance.

ERRORS REDUCING METHOD
To scan accurately the objects, we need: -Feedback the rotating position syncing with camera.
-Adjusting the parameters of images extracted from camera -Reducing the errors of capturing images when laser capture is projected to the object by using light aperture parameters adaptation selfconfigured.[4] With the model in the citation, Laser and space environment aren't integratedly filtered.The model of integrated filter groups includes: -Laser filter.
-Continuously reading data from encoder to identify the frames while other models do not use this method.
-Coupling data-arrays bases on rotation mechanic model, reducing time and reducing errors better than just only coupling by software.

The synchronization values method
On moving axis, servo motor will be arranged     Gray threshold filter: when the lasers data was existed, we will set the threshold to remove points that are not the laser (the laser is brighter).After performing above processes, we will have a laser curve on a black background, but there will be some thorny points, the task of the algorithm will remove that spikes.

Figure 1 -
Figure 1-c.Model of scanner rotation form: Reality model with constant velocity controller [2].Encoder signals are feedback continuously to the software and synchronized with image data obtained.The Open CV software turns into image continuously capture mode.We will allocate more time for the scanning position, so if the video capture mode does not respond promptly, we still have time enough to collate and process [5].

Figure 2 .
Figure 2. The capturing image time synchronized processing and encoder signals blocks diagram2.2Adjusting cameraBecause CCD camera has only one flat certain area, so we need to stretch flatly the scanning area.

Figure 3 -
Figure 3-a.Chessboard image set in front of camera.

Figure 3 -
Figure 3-b.Points of the chessboard indentifing image

Figure 4 .
Figure 4.The filtering processes of program

Figure 5 .Figure 6
Figure 5.The threshold of lasers description