سلمى
20-05-2005, 01:08 PM
عندي موضوع بالانجلش عن الاستشعار وابي ترجمة صحيحه له
حاولت اترجمه بالوافي بس ما فهمت له
الترجمه ماهي واضحه
ومحد عارف يترجمه له لانه فيه مصطلحات عن الاستشعار
تكفون اللي يقدر يساعدني لا يقصر معاي
وبكون شاكره لكم
الموضوع طويل ادري
بس انا ابي الزبده منه
اقصد ابي العوامل اللي تعيق المسح لبقع الزيت
طبعا بشرح واضح
ومشكورين مقدما
وهذا الموضوع
Algorithms of oil spill detection on SAR images
Satellite instruments are well adapted to monitor and therefore to detect oil pollution since they produce regularly images of the sea surface including the remote areas. Several kinds of measurements have A trained human operator is mostly able to discriminate between oil slicks and look-alikes based on experience, visual spill properties (shape and contrast between the feature and the surroundings sea), the presence and location of moving ships, oil platforms and other stationary objects relative to the dark features taking into account supplementary information (weather conditions, statistical data, geographical location of spill, and etc.) (Figure 1). The SAR signature of an oil spill and its surroundings as well as the spill shape depend on a number of parameters like wind speed, wave height, amount and type of oil released. The shape of the spill will also depend on the wind and current history between the release and the image acquisition.
The constraints related to SAR measurements are of several kinds. First, wind speed value has to be between 2-3 to 10-14 m/s. Secondly, it is rather hard to distinguish oil spill from other phenomena which analogously to oil spills have negative radar contrast (look dark on SAR images) relative the surrounding waters and commonly referred to as "look-alikes". Among such "look-alikes", are films of surface active substances (mainly, natural) observable particularly at wind speed < 5-6 m/s, wind shadow areas near the coast, heavy rains damping small scale roughness, upwelling zones and grease ice (Figure 2). Thirdly, the SAR image allows detecting oil on the ocean surface only, before it goes down in sub-surface layer as a result of dispersion (see: Behaviour oil at sea).
been tested: optical, infrared, radars with different frequencies. Below the main attention will be given to consideration of oil spills on Synthetic Aperture Radar (SAR) images. SAR seems to be one of the most suitable instruments to the detection of slicks since slicks damp strongly short waves measured by SAR and oil spills appear as a dark patch on the SAR image. SAR observations do not depend on weather (clouds) and sunshine, which allows showing illegal discharges that most frequently appear during night. SAR can also survey storms areas, where accident risks are increased.
http://cearac.poi.dvo.ru/en/research/detection/det_1a.jpg http://cearac.poi.dvo.ru/en/research/detection/det_1b.jpg
Figure 1. Subsections of ERS-2 SAR image for 20 May 1994 at 14:20 UTC (a) and for 23 March 1999 at 13:27 UTC (b) showing illegal discharge of oil-polluted waters by ships. Ships are clearly visible as white dots at the beginning of dark bands.
(a) Fresh discharge from a moving ship: dark band broadens as a function of the distance from the ship. Surface currents deform shape of oil band.
(b) Old discharge: ship on anchor. Width of the oil slick does not change.
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حاولت اترجمه بالوافي بس ما فهمت له
الترجمه ماهي واضحه
ومحد عارف يترجمه له لانه فيه مصطلحات عن الاستشعار
تكفون اللي يقدر يساعدني لا يقصر معاي
وبكون شاكره لكم
الموضوع طويل ادري
بس انا ابي الزبده منه
اقصد ابي العوامل اللي تعيق المسح لبقع الزيت
طبعا بشرح واضح
ومشكورين مقدما
وهذا الموضوع
Algorithms of oil spill detection on SAR images
Satellite instruments are well adapted to monitor and therefore to detect oil pollution since they produce regularly images of the sea surface including the remote areas. Several kinds of measurements have A trained human operator is mostly able to discriminate between oil slicks and look-alikes based on experience, visual spill properties (shape and contrast between the feature and the surroundings sea), the presence and location of moving ships, oil platforms and other stationary objects relative to the dark features taking into account supplementary information (weather conditions, statistical data, geographical location of spill, and etc.) (Figure 1). The SAR signature of an oil spill and its surroundings as well as the spill shape depend on a number of parameters like wind speed, wave height, amount and type of oil released. The shape of the spill will also depend on the wind and current history between the release and the image acquisition.
The constraints related to SAR measurements are of several kinds. First, wind speed value has to be between 2-3 to 10-14 m/s. Secondly, it is rather hard to distinguish oil spill from other phenomena which analogously to oil spills have negative radar contrast (look dark on SAR images) relative the surrounding waters and commonly referred to as "look-alikes". Among such "look-alikes", are films of surface active substances (mainly, natural) observable particularly at wind speed < 5-6 m/s, wind shadow areas near the coast, heavy rains damping small scale roughness, upwelling zones and grease ice (Figure 2). Thirdly, the SAR image allows detecting oil on the ocean surface only, before it goes down in sub-surface layer as a result of dispersion (see: Behaviour oil at sea).
been tested: optical, infrared, radars with different frequencies. Below the main attention will be given to consideration of oil spills on Synthetic Aperture Radar (SAR) images. SAR seems to be one of the most suitable instruments to the detection of slicks since slicks damp strongly short waves measured by SAR and oil spills appear as a dark patch on the SAR image. SAR observations do not depend on weather (clouds) and sunshine, which allows showing illegal discharges that most frequently appear during night. SAR can also survey storms areas, where accident risks are increased.
http://cearac.poi.dvo.ru/en/research/detection/det_1a.jpg http://cearac.poi.dvo.ru/en/research/detection/det_1b.jpg
Figure 1. Subsections of ERS-2 SAR image for 20 May 1994 at 14:20 UTC (a) and for 23 March 1999 at 13:27 UTC (b) showing illegal discharge of oil-polluted waters by ships. Ships are clearly visible as white dots at the beginning of dark bands.
(a) Fresh discharge from a moving ship: dark band broadens as a function of the distance from the ship. Surface currents deform shape of oil band.
(b) Old discharge: ship on anchor. Width of the oil slick does not change.
(