sun_mos_pro.tif: Image of the 4-m Sun-illuminated Topography of the Sea Floor off Eastern Cape Cod

The sun-illuminated topographic (shaded relief) image has a 4-m pixel size and was created by vertically exaggerating the topography two times and then artificially illuminating the relief by a light source positioned 45 degrees above the horizon from an azimuth of 0 degrees. In the resulting image, topographic features are enhanced by strong illumination on the northwestward-facing slopes and by shadows cast on southeastern slopes.

The image also accentuates small features (relief of a few meters) that could not be effectively shown as contours alone at this scale. Unnatural-looking features or patterns oriented parallel or perpendicular to survey tracklines are artifacts of data collection and environmental conditions. The data have a weak striping that runs parallel to the ship's track.

Some of the striping is the result of poor data return at nadir that appears as evenly-spaced thin speckled lines. Some striping is also due to critical angle effects, where the intensity of return varies as a function of the angle of incidence of the incoming sound on the seafloor (Hughes-Clark and others, 1997).

Note

The north and south sections of this data set were mosaiced and then reprojected from their native projection into North American Datum 1983 (NAD83) / Massachusetts State Plane coordinate system, Mainland Zone (Fipszone 2001) meters by the Massachusetts Office of Coastal Zone Management on Sept. 5, 2006.