Evaluating operational potential of video strip mapping in monitoring reinstatement of a pipeline route
The first part of this study evaluates whether video can be used to provide the information required for pipeline ROW monitoring. Comparisons of information content are made between the aerial photograph (as a representative of typical wide angel sensors) and video. The aerial photographic image had neither the ground pixel size nor inexpensive data within the narrow target due to its wide angle-of-view. The video realistically isolated the major communities of the narrow pipeline ROW by reliable spatial precision due to its narrow angle-of-view. These investigations led to the conclusions that video is the sensor, technically and economically, which can meet the information requirements for the proposed target. The second part of the study develops a digital mosaicking procedure for narrow strip video. Until now, due to the time consuming mosaic requirement, video imagery had tended to be neglected in a digital environment. A reliable mosaic creation method for strip video was developed by incorporating traditional analogue mosaicking and digital image processing. An interactive approach, registering video frames bi-directionally, produced an acceptable positional accuracy. The concept of bi-directional bridging is a major product of this project. Bi-directional bridging, requiring solely end lap, enables VSM to be a powerful remote sensing tool in terms of time and labour. The development of bi-directional bridging breaks down the typical concept of video as being used purely as a snapshot visual assessment tool. The final aspect of the project is related to change-detection of the pipeline ROW recovery. A definite requirement in post-construction management of the ROW site is to detect recovery status on a multi-temporal basis. However, such large-scale video systems are often discussed as being inadequate for a change-detection application due to geometric and radiometric calibration problems. In spite of such limitations, changes to several detailed land cover classes, particularly for the rapid recovered target of the ROW (usually 5-10 years), could be detected successfully by visual or quantitative methods and through further patch dynamics analysis in a GIS environment. The results of this study indicate that such calibration problems are generally not a major drawback in acquiring change-detection information in a practical operational application which requires mostly generalised thematic mapping for relatively simple classes.