Estimating the size composition of sediment surfaces through image analysis

This paper describes a technique to extract grain size information from areal images of sediment surfaces. An edge-detection algorithm is used to obtain the particle boundaries and segment the image into individual grains. Further processing of the segmented image can result in detailed information about grain size, position, orientation and, depending on the type of image, exposure. The images analysed in this paper were obtained by laser altimeter scans of sediment surfaces in laboratory conditions. Further development of the method could harness photo-grammetric methods which are currently under development as a means of obtaining suitable images. Alternatively, carefully lit photographs have the potential to provide sufficient contrast at grain edges for the successful implementation of the image-processing technique. Therefore, this paper can be regarded as an interim step towards the provision of an improved method for estimating surface sizes and composition. The results presented are sufficiently encouraging to make field trials, probably with other image types, an attractive possibility.