Point-Clouds as Photogrammetric Representations of Linear Objects Surfaces : the Impact of Extrinsic Shooting Parameters on the Change of Roughness-Quality of Their Textures

Abstract

This paper investigates the impact of various extrinsic shooting parameters regarding change of roughness-quality of surface textures of linear objects/elements when presented in the form of unstructured photogrammetrially created point-clouds. To perfom this scientifically-wise, two types of specific quality-descriptors are identified: process-quality descriptors and smoothness related quality descriptors. Then, they are precisely defined, computed and mutually correlated. It can be generally concluded that for a fixed focal length, shooting directions perpendicular to the axis of targeted object/element, stationpoints uniformly radially distributed around it (at a circle of 360 deg.) and obtained process-quality descriptors values that belong to satisfying /recommended ranges, the performed photogrammetric digitalization is declared highly precise and satisfyingly accurate regarding roughness /smoothness and barely prone to object-to-camera distance.