基于无监督学习的岩体孔壁全景展开图像拼接方法

Unsupervised learning-based panoramic unfolded image stitching method for rock mass borehole wall

  • 摘要: 岩体孔壁全景展开图像拼接时采用传统方法时存在相邻图像间建立特征对应关系的鲁棒性不足,提取的图像特征点质量差、数量少等问题,采用有监督学习方法无法获取足够精确标注的匹配点对。针对上述问题,提出了一种基于无监督学习的岩体孔壁全景展开图像拼接方法。通过基于分组卷积改进的ResNet网络对相邻2幅待拼接的岩体孔壁全景展开图像进行多尺度特征提取;引入匹配度交叉相关计算模块识别和对齐特征图中的特征,进而确定对应特征图间的空间关系;通过全局和局部变形偏移量计算网络模块对图像进行精确的空间特征对齐;通过单应性变形模块与图像网格变形模块,有效消除相邻图像间的特征变形,实现图像间的整体对齐和精细的局部调整,精准配准局部特征和变形。实验结果表明:该方法能有效克服图像特征偏移、内容错位、细节特征丢失和拼接失败等问题,拼接处几乎没有明显的拼接痕迹,提高了拼接图像的整体质量和视觉效果;在均方根误差(RMSE)、重叠区域的峰值信噪比(PSNR)和结构相似性(SSIM)指标上均优于其他主流的图像拼接方法,显著提升了岩体孔壁全景展开图像拼接精度。

     

    Abstract: Traditional methods for panoramic unfolded image stitching of rock mass borehole walls suffer from insufficient robustness in establishing feature correspondences between adjacent images, as well as poor quality, limited quantity of extracted image feature points and otherc problems. Meanwhile, supervised learning methods cannot obtain sufficiently precise labeled matching point pairs. To address these issues, an unsupervised learning-based panoramic unfolded image stitching method for rock mass borehole wall is proposed. Multi-scale feature extraction was performed on two adjacent panoramic unfolded images of the rock mass borehole wall to be stitched, using a ResNet network improved with grouped convolutions. A matching degree cross-correlation calculation module was introduced to identify and align features within the feature maps, thereby determining the spatial relationships between corresponding feature maps. A global and local deformation offset calculation network module precisely aligned spatial features of the images. Furthermore, homography deformation and image grid deformation modules effectively eliminated feature distortions between adjacent images, achieving overall alignment and fine local adjustments, enabling accurate registration of local features and deformations. Experimental results showed that this method effectively overcame issues such as image feature displacement, content misalignment, loss of detailed features, and stitching failure. The stitching seams exhibited almost no visible artifacts, improving the overall quality and visual effect of the stitched images. The method outperforms other mainstream image stitching approaches in terms of Root Mean Square Error (RMSE), Peak Signal-to-Noise Ratio (PSNR) in overlapping regions, and Structural Similarity (SSIM) index, significantly enhancing the stitching accuracy of panoramic unfolded images of rock mass borehole walls.

     

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