This image was generated using both the bathymetry and shaded relief images. By digitally combining these two data sets, both the elevation and structural information can be shown in the same image. The bathymetry data were color-coded to cover the depth range from 1 to 115 meters. The scale at the bottom of the image represents water depth in approximately 2.9-meter increments. The on-land data is from a portion of an IRS-IC satellite Pan image with approximately 6 meter resolution.

The shaded relief image generated from the bathymetry data. Utilizing digital image processing techniques, a shaded relief image can be generated with the sun positioned at any desired elevation and azimuth. This enhances the topographic component in the data, including surface fracture, linear features, faults, folds, drainages, and slopes. Several topographic landforms are easily seen in this image. Large sand waves, as well as the build up of dredged material, can be seen to the southwest and south of Alcatraz Island, respectively. Also, the three rock pinnacles to the northwest of Alcatraz Island can be seen in this image. They are Harding Rock (northwest), Shag Rock (center), Arch Rock (southernmost). The linear feature to the left of the pinnacles is a rock outcrop that is partially covered by sediment. The on-land data is from a portion of an IRS-IC satellite Pan image with approximately 6 meter resolution.

The stereo image is also the shaded relief image discussed above; however, the bathymetry data were used to create a stereo pair. Parallax was introduced into the shaded relief image in the horizontal direction using the bathymetry data to generate the stereo image. The stereo/3-D image can be viewed by using red/blue or red/green (red on the left) glasses. This is an excellent way to study and analyze the topographic component of an area and show the local and regional slope information. Note how well the sandwaves, dredged material mound south of Alcatraz Island, and the three rock pinnacles northwest of Alcatraz Island, are expressed in the 3-D image. The on-land data is from a portion of an IRS-IC satellite Pan image with approximately 6 meter resolution.

Color-Coded Shaded Relief Image (226 kb) TEXT	Shaded Relief Image (151 kb) TEXT	Stereo Shaded Relief Image (148 kb) TEXT