Images of Faure Sill, Shark Bay, Western Australia. Images A to D are about 20km wide; image E is a perspective of a section of these. Image descriptions are as follows: (A) Landsat TM bands 1,2 and 3 combined in red, green and blue (RGB) respectively. Note that colours of bottom-types are subdued by contrast effects due to changing water depth. wide. (B) Substrate reflectance derived from SWIM processing of bands 1,2 and 3 (=RGB) after the removal of water depth effects. Blue and cyan colours indicate aquatic vegetation, largely seagrass, and reds and yellows are sandy areas. (C) SWIM derived water depth, bright tones are deeper. (D) Bottom structures highlighted by applying artificial illumination to the depth image and substituting the result for the intensity of image B using the hue, saturation and intenstity (HSI) technique. (E) A 3D perspective image of the sill using inverted depths as elevation and substrate colours derived from the SWIM algorithm.