Effect of Reduced Resolution on Image Quality

These images were taken using a test system we are developing at the University of Washington's Applied Physics Lab. The system is a single-channel sonar which uses two thin acoustic lenses to focus sound. The system is scanned across the underwater landscape on a ram mounted in the R/V J.E. Henderson , one of APL's research vessels. These images were taken in Lake Union.

In a working diver-held system, the beams will be formed simultaneously, rather than by scanning a single element. Fewer beams and a slower sampling rate means a faster, cheaper, and smaller system. However, fewer beams means reduced resolution in azimuth and a slower sampling rate means reduced resolution in range.

The resolution of the test sonar system is 0.09 degrees in azimuth by 0.5 cm in range. By ignoring data appropriately, we can simulate the images which would be obtained using a system with less resolution. These images explore the effects of reduced resolution in both range and azimuth. Note that the resolution of these pictures is less than 0.5 cm in range due to the limited number of pixels available.

The smoothed images were created by linear interpolation in azimuth. The images were not smoothed in range. The non-smoothed images (and all images in range) were created using pixel replication.

Sector Scan Images

Rowboat Images

Tire Graveyard Images

Test Barrel Images

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kfink@scn.org