CAJ | 학술논문

棋盘图像的角点提取问题往往决定着三维测量中摄像机标定的精度。针对SUSAN(Smallest Univalue Segment Assimilating Nucleus)算法无法区分棋盘标定板内角点与边缘点的缺陷，提出一种12像素对称灰度模板检测算法。该算法首先根据棋盘格内角点周围像素的中心对称性分布,设计一种12像素对称USAN模板，可以迅速区分出内角点与边缘点，同时将内角点与平坦区域作为候选点。再结合灰度均方差算子，利用平坦区域灰度方差较小的特点将其剔除，最终实现对棋盘格内角点的高效检测。同时，该算法在检测过程中完全摒除易受外界因素影响的外圈角点，以保证角点提取时的精度。实验结果表明：新算法对9阶棋盘格的检测时间为1.244577 s；用于张正友标定方法之后，得到的检测重投影误差仅为[0.3,0.3]像素。这两项指标，均优于传统SUSAN算法。
기반도상적각점제취문제왕왕결정착삼유측량중섭상궤표정적정도。침대SUSAN(Smallest Univalue Segment Assimilating Nucleus)산법무법구분기반표정판내각점여변연점적결함，제출일충12상소대칭회도모판검측산법。해산법수선근거기반격내각점주위상소적중심대칭성분포,설계일충12상소대칭USAN모판，가이신속구분출내각점여변연점，동시장내각점여평탄구역작위후선점。재결합회도균방차산자，이용평탄구역회도방차교소적특점장기척제，최종실현대기반격내각점적고효검측。동시，해산법재검측과정중완전병제역수외계인소영향적외권각점，이보증각점제취시적정도。실험결과표명：신산법대9계기반격적검측시간위1.244577 s；용우장정우표정방법지후，득도적검측중투영오차부위[0.3,0.3]상소。저량항지표，균우우전통SUSAN산법。
The problem of chessboard image corner extraction always determined the three-dimensional measurement′s accuracy of the camera calibration. By analyzing the defect for SUSAN (Smallest Univalue Segment Assimilating Nucleus) algorithm that could not effectively distinguish the chessboard internal corners and edge points, the authors made use of the symmetry of the pixels around the internal corners, and proposed a symmetrical 12 pixels gray template detection algorithm. Firstly, a symmetrical 12 pixels USAN template was designed for fast distinguishing the internal corners and edge points. Meanwhile, both of the chessboard internal corners and smooth region would be treated as the candidates. Then the less gray variance of smooth region could be used to abandon them. At the same time, the proposed algorithm abandoned the external corners of the chessboard, which were very sensitive to the external factors, ensuring the precision of the corner extraction process. Experimental results show that the new method detects the nine order chessboard image by1.244 577s, and its reprojection error was just [0.3, 0.3] pixels in Zhang′s camera calibration. Both of these two indicators are better than the traditional SUSAN algorithm.