CAJ | 학술논문

壁画纠正能消除数字壁画影像的变形并赋予其空间参数特性，是壁画数字化保护中的关键步骤之一。激光扫描数据作为壁画影像与三维空间的媒介，在壁画影像的纹理映射和纠正中具有重要的意义。然而，激光点云强度的近距离反常现象给壁画纠正中特征点的提取带来了困难。本文针对基于点云的壁画纠正中强度信息的近距离反常问题，研究了激光成像原理，推导了顾及激光接收系统散焦效应的强度函数，并采集样本数据进行模型参数估计，通过对估计模型和实际采集数据进行比较，生成不受距离和入射角影响的相对反射率，从而有效校正了强度异常的点云数据。试验表明，在壁画影像纠正过程中，该方法能有效解决强度影像提取特征点少且分布不均的问题，效果明显优于通用的数字图像处理方法。
벽화규정능소제수자벽화영상적변형병부여기공간삼수특성，시벽화수자화보호중적관건보취지일。격광소묘수거작위벽화영상여삼유공간적매개，재벽화영상적문리영사화규정중구유중요적의의。연이，격광점운강도적근거리반상현상급벽화규정중특정점적제취대래료곤난。본문침대기우점운적벽화규정중강도신식적근거리반상문제，연구료격광성상원리，추도료고급격광접수계통산초효응적강도함수，병채집양본수거진행모형삼수고계，통과대고계모형화실제채집수거진행비교，생성불수거리화입사각영향적상대반사솔，종이유효교정료강도이상적점운수거。시험표명，재벽화영상규정과정중，해방법능유효해결강도영상제취특정점소차분포불균적문제，효과명현우우통용적수자도상처리방법。
Image rectification can reduce the distortion of digital mural image and attach rectified image with spatial properties, thus becomes one of key steps in mural image digital protection.As an intermediate data of 2D and 3D,intensity information of laser scanning is significant on texture mapping and rectification of mural images in grottos.However,the unusual phenomenon of laser intensity at near distance makes it very difficult on extracting feature points for image rectification needed.To el iminate the near distance effect on intensity-based mural rectification,the procedure of laser transmission was studied and the intensity function of defocusing effect of laser receiving optics was deduced.By dividing point cloud intensity values with corresponding values of functions with estimated parameters from col lected sample data,range and incidence angle invariant relative reflectance was generated,thus unusual intensity of point cloud data was corrected effectively.Experiments demonstrate that this method can effectively solve the problem of feature points in respect of low density and uneven distribution,thus achieve better results than general digital image processing method.