Here is an example of the output of LANDSAT Shorelines.....
Land is black & white. Water area is color coded, with dark blue indicating 100% immersion ("deep water") and red or brown indicating mostly above tide. The percentage is based on the frequency of water cover detected in the images used for the analysis. The more images, the more reliable the percentage. On top is text reading "Station: El Golfo....Tide range in images: -2.2/-0.7m ...." This means the predicted tidal range was -2.2 to +0.7m when the satellite images were captured. The prediction is based on a standard model and is for the nearest tide station, which in this case is nearby El Golfo de Santa Clara. The overall range of tide at this station is -3.9 to +3.9 m, which is over twice the range observed with the selected images. The satellite data thus did not capture the full extent of the tidal zone.
Below is a close up on farm irrigation or aquatic farming activity. In the time period covered by the imagery the water ponds were utilized 20-40% of the time.
Stripes are often seen in LANDSAT 7 imagery from April, 2003 on. The stripes are due to the SLC-off state. (See the USGS web page on the SLC failure.) jCube fills in the data gaps statistically, but it can't be perfect and the stripes are residual errors or uncertainties. The above example used SLC-on data. The following is the same geographical area with SLC-off image data, showing some residual striping.
The water-land discrimination is usually accurate but there is at least one notable exception: mountain slopes can be mistaken for water when the sun altitude is <30 degrees. Example of this can be seen in processing the mountainous areas of this image. In a future upgrade there will be an option to exclude low sun altitude images.
Contact jCube@jOmegak.com for more information about jCube.
© 2008 jOmegak