A 3D Reconstruction Method Based On Cross Structured Light And Accuracy Analysis

The 3D measurement with structured light is one of the most commonly method to measure the geometric parameters and to reconstruct surfaces of objects. It has such advantages as non-contract, large measurement range, fast speed and high precision, etc. Now, it is widely used in industrial inspectionSingle structured light(SSL) is widely used in 3D measurement. There are some disadvantages in the 3D reconstruction using SSL, such as incomplete reconstructed information. To overcome or improve these problems, 3D reconstruction based on cross structured light(CSL) is studied in this paper. The results show that CSL system can recover more complete contour and provide more information of the measured surface than SSL system. Main research contents and results are included:1) Construction model of 3D reconstruction system with CSL. The mainly feature of CSL is that the laser planes nearly vertical, so that CSL can get more information than SSL. Model of the whole system was constructed in this paper, and the principle of each module is analyzed.2) A calibration method of laser plane based on laser intersection line was improved. The two laser planes of the CSL projector are generated from the same light source, and split by a special spectroscope. However, the angle between the two laser planes is not 90° exactly. So, the two laser planes of the CSL projector are regarded as two stand-alone laser planes to perform the calibration. So it is necessary to distinguish the laser light use RANSAC algorithm. The method proposed in this paper was combined with the basic algorithms such as linear fitting and surface fitting, which is not only simple but also with high precision.3) An extraction and classification method of laser stripe centers was improved, which could result in both high accuracy and high efficiency. After compared the variety of tradition methods, an extraction method combining fast thinning algorithm, Hessian matrix and gray weighted center algorithm was put forward. All center points are located at the two crossed laser stripes, so they need to be divided into two groups where all center points come from the same laser stripe. In this paper, points can be distinguished by their normal direction though Hessian matrix.4) Construction of the experimental platform of the entire system. According to 3D reconstruction model, the corresponding experimental platform was build, which included hardware and software equipment. The image acquisition, image processing and 3D reconstruction can be effectively realized.5) Reconstruction precision analysis. A known cylinder was reconstructed, and the reconstruction error and its sources were analyzed. Reconstruction with an example of shoe last proves that the proposed reconstruction method based on CSL can obtain more abundant information than that based on SSL, which illustrates the practicability of the method proposed in this paper.