DIGITAL MAPS OF THE SEABED COLOR RENDERED IN TRUE COLOR

The color of seabed sediments is an important geological indicator of river outfall footprints, ocean oxygen layering, submarine outcrops of older horizons, hydrothermal activity and sediment provenance including terrigenous vs biogenic. For the first time, digital mappings of seabed color are available, built through the processing of information from large datasets (104 samples) acquired over many years of research.

Information on color is typically made available in geological datasets as Munsell Codes (GSA Rock Color Chart) or word-based descriptions (names). The Munsell codes of hue/value/chroma (HVC) are extracted from a variety of (typographic) formats and reported to output in one uniform format that can be drawn on by GIS. The word based descriptions are parsed to separate the functional classes of words: objects carrying absolute meanings, modifiers that have relative meaning and quantifiers that attach a weighting. For example: "occasionally [Q] very_dark [M] green [O]". The colour meaning of objects is conveyed as hue/value/chroma with a weighting; of modifiers as weighted adjustments to value and chroma. The mixing and combination of terms is performed in CIE colorspace which unlike Munsell HVC colourspace is linear and capable of supporting arithmetic operations. The resultant color is returned to Munsell colorspace. Validation of the process is done using datasets where the parsed output code can be compared to an original Munsell code observation. For hue, value and chroma the R²correlation statistics are 0.95, 0.7 and 0.3. A large part of these variations took place at time of the original observations. True-color display is achieved in the GIS displays by adjusting symbol colours to match the output Munsell codes.

Displays of seabed colour mappings are presented for the US east and west continental shelf areas and the Australasian region. They provide a new way to view the seabed rather like large-scale color remote sensing of the land.