期刊名称：ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences
印刷版ISSN：2194-9042
电子版ISSN：2194-9050
出版年度：2008
卷号：XXXVII Part B5
页码：1-6
出版社：Copernicus Publications
摘要：The use of consumer grade digital cameras for spatial measurement has rapidly increased over the past decade and is accepted in many industrial applications but also in diverse fields ranging from medical science to architectural work. Their uncertain internal geometry can be partially resolved by calibration. Research recent conducted at Loughborough University indicated the potential of consumer grade digital sensors to maintain their internal geometry but also identified residual systematic error surfaces, discernible in digital elevation models (DEM), which are caused by slightly inaccurately estimated lens distortion parameters.These remaining systematic errors degrade the accuracy of data that can be extracted.The stereopair configuration remains important for data extraction in photogrammetry, one that is employed by automated DEM extraction software. The aerial photogrammetric normal case is widely used, in which the camera base is parallel to the object plane and the camera axes intersect the object plane orthogonally. Initial results have demonstrated that using a convergent image configuration, where the optical camera axes intersect the object plane at the same point, minimises the residual systematic error surfaces in DEMs, even if extracted using inaccurately estimated lens distortion parameters. The developed methodology was tested using simulated data and verified by a practical test. However, such simple configurations are inflexible since almost every measurement task in close range photogrammetry, desires a unique image configuration, which is often oblique.This paper will demonstrate, how this simple constraint, which can be introduced to almost every stereopair configuration used for DEM generation, can minimise these systematic errors and may be suitable for many spatial measurement applications. A series of practical tests were conducted to verify the results from the simulation. In the first, accurate measurement and modelling of a flume bed surface, using digital photogrammetry, provided the opportunity to conduct a suitable case study in a semi-controlled environment. A flume or simulated river bed, located in a laboratory, needed to be measured. A series of images were acquired using a consumer grade digital camera (Canon EOS 10D). These included the normal case and a convergent configuration. Mosaic DEMs were extracted and this work and the accuracy achieved is presented.Flooding can cause loss of life and property and research activities in flood management are essential to determine accurately the flood conveyance. Accurate water surface elevation data are essential to develop computational flow models and a remote water surface measuring technique could be provided using digital photogrammetry. In the second case study, a photogrammetric method was developed to measure a dynamic water surface on a small river in Loughborough. A pair of synchronised Nikon D80 digital cameras were used to capture stereo image pairs (normal and convergent configuration) of the water surface. A fixed, horizontal survey staff located above the water surface, was used to access accuracy. This paper will demonstrate that a mildly convergent image configuration for DEM extraction, minimises residual systematic error surfaces caused by slightly inaccurately estimated lens distortion parameters. This approach effectively improves the accuracy achievable with non-metric sensors and provides an alternative approach to the need for an explicit and exact lens model
关键词：Close Range Photogrammetry; Digital Camera; Digital Photogrammetry; Image Configuration
