基于激光点云的园林假山遗产特征定量化评价

Quantitative Evaluation of Garden Rockery Heritage Characteristics Based on Laser Point Cloud

基于湖石假山特征定量化评价的一种新方法,利用激光扫描采集高精度环绕式假山点云数据,分析点云模型的骨架线、轮廓转折点、透窝洞、粗糙度等关键特征,并以传统品赏标准中的“瘦、透、漏、皱”为引导,建立由体占比、透空率、洞穿率等14个指标构成的定量评价体系。通过对上海和扬州的假山实例研究,得出漏空比、出孔率、切占比和孔心分布系数能够综合反映假山“漏”的特征;透空率、出洞率、洞穿率和洞心分布系数能够表征“透”的特征;粗糙度和粗糙率能够表征“皱”的特征;体占比、转折数、轮廓弯曲度和骨架复杂度能够综合反映“瘦”的特征。方法有效利用了激光点云高精度、多细节的特点,结合数理分析及计算机可视化等手段构建了定量评价途径,为园林假山遗产的保护和传承提供了更科学的依据和新的思路。

An innovative approach for quantitatively evaluating the Taihu Lake stone rockery characteristics was created in this research.Key features of the digital model,including model skeleton extraction,contour scatter extraction,geometric holes,and texture roughnes,were examined.High-precision surrounding rockery point cloud data were collected using laser scanning.Based on the traditional Chinese evaluation criteria for garden rockeries,“Shou(slim),Tou(riddled through),Lou(well hollowed out),and Zhou(wrinkled)”,a quantitative evaluation system with 14 indicators,such as body proportion,air permeability,and penetration rate,was proposed.It was determined through the case study of rockery in Shanghai and Yangzhou that the characteristics of“Lou(well hollowed out)”can be seen in the mutual weighting of leakage ratio,porosity,tangent ratio,and hole center distribution coefficient;the air permeability,the hole rate,the hole penetration rate,and the hole center distribution coefficient can represent the characteristic of“Tou”(riddled through);“Zhou(wrinkled)”can be seen in the two indicators of roughness and roughness ratio;the body proportion,inflection number,contour curvature,and skeleton complexity can fully reflect the characteristic of“Shou”(slim).This method effectively makes use of the high-precision and multi-detail characteristics of laser point clouds.It also combines mathematical analysis and computer visualization.The quantitative evaluation approach can provide a scientific basis and new visions for the conservation and transmission of garden rockery heritage.