Centre for Remote Imaging, Sensing and Prcessing (CRISP)
|Contact: firstname.lastname@example.org||Copyright © CRISP, 2001|
| Synthetic Aperture Radar (SAR) is
a valuable tool for monitoring ships because of its all-weather,
day/night capabilities, and its wide coverage area. Much information
about detected ships can be derived from the SAR image, including
the ship's location, heading, length, velocity, and possibly shiptype.
Ships in SAR Images
Ship Wakes in SAR ImagesMany types of wakes can be seen in SAR images, depending on the ambient and imaging conditions. These include turbulent wakes, Kelvin envelops, transverse waves, internal wave wakes, and narrow-V wakes[LINK TO PAGE ABOUT SHIP WAKE OBSERVATION].
In SAR images, moving ships are displaced from their wakes due to an effect known as the Doppler Effect. The wakes and their displacement further provide estimates of the ships’ velocity.
This ERS SAR image shows two ships moving in opposite directions in the Malacca Strait. Both ships are displaced vertically from their dark turbulent wakes. Calculations yield values of 6 and 12.5 m/s for the speed of the left and right ships respectively.
CRISP’s Ship and Ship Wake Detection SystemCRISP’s ship and ship wake detection system can process both ERS and RADARSAT images, and produce visual and textual information about the detected ships, such as the location, speed, heading, length and wake type of each ship.
Sample Graphic Output
The detected ships are highlighted in purple in this sample graphic output of the ship detection system. Large clusters of ships can be seen in the docking areas. The yellow regions in the image indicate mainly land areas which were masked out by the system.
A close-up of a graphic output shows the detection results more clearly. Detected ships are coloured cyan and highlighted by purple circles, while detected wakes are indicated by wake lines. Calculated ships headings are also marked. The detected ships in the image are annotated by numbers. The information about the ships are given in the textual output.
Textual OutputThe textual listing provides detailed information regarding the ships, including its location, speed, heading, length and wake type. It also contains information about the image itself, such as the latitude/longitude, time/date, and satellite incidence angle etc.
|Copyright © CRISP, 2001|