The coastline changes along Yemen＇s the Red Sea （Al-muka, Al-khohah, Al-tiaf, Ras Katib and Al- Urji spits） were studied using a series of landsat images （MSS, TM and ETM ＋ , 1972, 1989, 2000, 2006）, coupled wit...The coastline changes along Yemen＇s the Red Sea （Al-muka, Al-khohah, Al-tiaf, Ras Katib and Al- Urji spits） were studied using a series of landsat images （MSS, TM and ETM ＋ , 1972, 1989, 2000, 2006）, coupled with geomorphological, sedimentological and meteorological findings. Comparison of satellite images provided a viable means for establishing long-term coastal changes （accretion and erosion） as observed in the studied spits （Al-Urj, Ras Sham, Ras Maemoon, Ras Katib, Al-Mandar, Nukhaylah, Mujamilah, Ras Ashab Abu-Zahr and Mukha）. The rate of the spit accretion has the greatest value up to 89 pixel/year corresponding to 72 290 m2/year in Mukha, while the spit erosion shows greatest value up to 131 pixel/year corresponding to 106 404 m2/year in Mujamilab. The patterns of accretion and erosion along the spits depend on the spit direction, natural processes mainly of wave-induced longshore currents, the sediments supply and depth of sea.展开更多
In this paper,a technique based on image pyramid and Bayes rule for reducing noise effects in unsupervised change detection is proposed.By using Gaussian pyramid to process two multitemporal images respectively,two im...In this paper,a technique based on image pyramid and Bayes rule for reducing noise effects in unsupervised change detection is proposed.By using Gaussian pyramid to process two multitemporal images respectively,two image pyramids are constructed.The difference pyramid images are obtained by point-by-point subtraction between the same level images of the two image pyramids.By resizing all difference pyramid images to the size of the original multitemporal image and then making product operator among them,a map being similar to the difference image is obtained.The difference image is generated by point-by-point subtraction between the two multitemporal images directly.At last,the Bayes rule is used to distinguish the changed pixels.Both synthetic and real data sets are used to evaluate the performance of the proposed technique.Experimental results show that the map from the proposed technique is more robust to noise than the difference image.展开更多
文摘The coastline changes along Yemen＇s the Red Sea （Al-muka, Al-khohah, Al-tiaf, Ras Katib and Al- Urji spits） were studied using a series of landsat images （MSS, TM and ETM ＋ , 1972, 1989, 2000, 2006）, coupled with geomorphological, sedimentological and meteorological findings. Comparison of satellite images provided a viable means for establishing long-term coastal changes （accretion and erosion） as observed in the studied spits （Al-Urj, Ras Sham, Ras Maemoon, Ras Katib, Al-Mandar, Nukhaylah, Mujamilah, Ras Ashab Abu-Zahr and Mukha）. The rate of the spit accretion has the greatest value up to 89 pixel/year corresponding to 72 290 m2/year in Mukha, while the spit erosion shows greatest value up to 131 pixel/year corresponding to 106 404 m2/year in Mujamilab. The patterns of accretion and erosion along the spits depend on the spit direction, natural processes mainly of wave-induced longshore currents, the sediments supply and depth of sea.
基金the National Basic Research Program(973) of China (No. 2006CB701303)the National High Technology Research and Development Program(863) of China (No. 2006AA12Z105)
文摘In this paper,a technique based on image pyramid and Bayes rule for reducing noise effects in unsupervised change detection is proposed.By using Gaussian pyramid to process two multitemporal images respectively,two image pyramids are constructed.The difference pyramid images are obtained by point-by-point subtraction between the same level images of the two image pyramids.By resizing all difference pyramid images to the size of the original multitemporal image and then making product operator among them,a map being similar to the difference image is obtained.The difference image is generated by point-by-point subtraction between the two multitemporal images directly.At last,the Bayes rule is used to distinguish the changed pixels.Both synthetic and real data sets are used to evaluate the performance of the proposed technique.Experimental results show that the map from the proposed technique is more robust to noise than the difference image.
