Measuring flume surfaces for hydraulics research using a Kodak DCS460

A critical problem in hydraulics research is accurate measurement of fluvia lly worked sediments, both in the field and in scaled representations of fi eld situations in laboratory flumes. Such measurement must provide informat ion on individual gran characteristics, and their organisation into structu res referred to as bedforms. Existing measurement approaches are based upon mechanical or laser profiling devices, which are both expensive and take c onsiderable time to acquire data, particularly where information is require d at very high densities. This paper demonstrates how conventional automate d terrain model taction software, combined with image acquisition using a K odak DCS460 digital camera, has been effective in generating digital elevat ion models of complex bed morphology. This has reduced time spent collectin g data in the flume and has allowed data collection at much higher spatial and temporal densities. Application of the method is illustrated by researc h carried out at Hydraulics Research Wallingford. Issues discussed include configuration of photographs and control coordinates; appropriate camera ca libration methods stability of inner orientation of the Kodak DCS460; and a ccuracies obtained. Comparisons with independent check data reveal that acc uracies of +/-2.5 mm have been achieved using a camera-to-object distance o f 4.2 m.