【目的】中国传统园林空间复杂多变,传统的分析方法难以深入探索传统园林复杂的三维视觉空间特征。三维激光雷达(light detection and ranging,LiDAR)点云技术在传统园林空间研究方面具有精度高、信息全等优势,借助LiDAR点云技术深入探...【目的】中国传统园林空间复杂多变,传统的分析方法难以深入探索传统园林复杂的三维视觉空间特征。三维激光雷达(light detection and ranging,LiDAR)点云技术在传统园林空间研究方面具有精度高、信息全等优势,借助LiDAR点云技术深入探索中国传统园林视觉空间特征,可为现代人居环境空间营造提供借鉴与参考。【方法】基于LiDAR点云技术提出一套适用于中国传统园林视觉空间分析的方法,并以三维可视性、视野舒展度及景物视野占比3项指标量化描述视觉空间。【结果】以寄畅园为例,构建了寄畅园LiDAR点云体素模型,利用提出的方法对锦汇漪西侧滨水步道11个视点的视觉空间进行了量化分析,解析了寄畅园的视觉空间特征,并探究了该步道的空间感知序列。【结论】证实了利用LiDAR点云技术展开传统园林视觉空间研究的可行性与准确性,提出的方法可应用于其他传统园林视觉空间的分析研究中。展开更多
A multipurpose image watermarking technique based on DCT is proposed to notify and protect the copyright of digital products. In order to achieve this objective, the DCT coefficients of each image block are divided in...A multipurpose image watermarking technique based on DCT is proposed to notify and protect the copyright of digital products. In order to achieve this objective, the DCT coefficients of each image block are divided into two parts for embedding the visible and invisible watermarks. The visible watermark is embedded in each DC DCT coefficient and most of the AC DCT coefficients of every block, and the invisible watermark in the rest. Based on the characteristics of Human Visual System (HVS), the embedding strength of the visible watermark is varied in accordance with the underlying content of the host image. The invisible watermark is embedded in a quaternity of midrange frequencies. Experimental results show that the visible watermark is hard to remove and the invisible watermark is robust to common digital signal processing operations.展开更多
文摘【目的】中国传统园林空间复杂多变,传统的分析方法难以深入探索传统园林复杂的三维视觉空间特征。三维激光雷达(light detection and ranging,LiDAR)点云技术在传统园林空间研究方面具有精度高、信息全等优势,借助LiDAR点云技术深入探索中国传统园林视觉空间特征,可为现代人居环境空间营造提供借鉴与参考。【方法】基于LiDAR点云技术提出一套适用于中国传统园林视觉空间分析的方法,并以三维可视性、视野舒展度及景物视野占比3项指标量化描述视觉空间。【结果】以寄畅园为例,构建了寄畅园LiDAR点云体素模型,利用提出的方法对锦汇漪西侧滨水步道11个视点的视觉空间进行了量化分析,解析了寄畅园的视觉空间特征,并探究了该步道的空间感知序列。【结论】证实了利用LiDAR点云技术展开传统园林视觉空间研究的可行性与准确性,提出的方法可应用于其他传统园林视觉空间的分析研究中。
文摘A multipurpose image watermarking technique based on DCT is proposed to notify and protect the copyright of digital products. In order to achieve this objective, the DCT coefficients of each image block are divided into two parts for embedding the visible and invisible watermarks. The visible watermark is embedded in each DC DCT coefficient and most of the AC DCT coefficients of every block, and the invisible watermark in the rest. Based on the characteristics of Human Visual System (HVS), the embedding strength of the visible watermark is varied in accordance with the underlying content of the host image. The invisible watermark is embedded in a quaternity of midrange frequencies. Experimental results show that the visible watermark is hard to remove and the invisible watermark is robust to common digital signal processing operations.
