Recently land-use change has been the main concern for worldwide environment change and is being used by city and regional planners to design sustainable cities. Nakuru in the central Rift Valley of Kenya has undergon...Recently land-use change has been the main concern for worldwide environment change and is being used by city and regional planners to design sustainable cities. Nakuru in the central Rift Valley of Kenya has undergone rapid urban growth in last decade. This paper focused on urban growth using multi-sensor satellite imageries and explored the potential benefits of combining data from optical sensors (Landsat, Worldview-2) with Radar sensor data from Advanced Land Observing Satellite (ALOS) Phased Array type L-band Synthetic Aperture Radar (PALSAR) data for urban land-use mapping. Landsat has sufficient spectral bands allowing for better delineation of urban green and impervious surface, Worldview-2 has a higher spatial resolution and facilitates urban growth mapping while PALSAR has higher temporal resolution compared to other operational sensors and has the capability of penetrating clouds irrespective of weather conditions and time of day, a condition prevalent in Nakuru, because it lies in a tropical area. Several classical and modern classifiers namely maximum likelihood (ML) and support vector machine (SVM) were applied for image classification and their performance assessed. The land-use data of the years 1986, 2000 and 2010 were compiled and analyzed using post classification comparison (PCC). The value of combining multi-temporal Landsat imagery and PALSAR was explored and achieved in this research. Our research illustrated that SVM algorithm yielded better results compared to ML. The integration of Landsat and ALOS PALSAR gave good results compared to when ALOS PAL- SAR was classified alone. 19.70 km2 of land changed to urban land-use from non-urban land-use between the years 2000 to 2010 indicating rapid urban growth has taken place. Land-use information is useful for the comprehensive land-use planning and an integrated management of resources to ensure sustainability of land and to achieve social Eq- uity, economic efficiency and environmental sustainability.展开更多
矿区土地覆盖变化信息的高精度提取,是区域资源环境保护和地质灾害防治领域的关键问题。以SPOT-5高分辨率卫星影像为数据源,以分类后比较法为变化信息提取方法,利用分类性能良好的支持向量机(SVM)为分类算法,分别设置不同SVM核函数及参...矿区土地覆盖变化信息的高精度提取,是区域资源环境保护和地质灾害防治领域的关键问题。以SPOT-5高分辨率卫星影像为数据源,以分类后比较法为变化信息提取方法,利用分类性能良好的支持向量机(SVM)为分类算法,分别设置不同SVM核函数及参数对实验样区进行分类,并评价分析不同核函数及参数对分类效果的影响。实验发现在4种核函数中高斯核函数分类精度最高,为87.1%;Sigmoid和多项式核函数分类精度适中,线性核函数分类精度最低,为78.7%。因此,利用高斯核函数分别对3个时相的大屯矿区影像进行分类,提取出变化信息空间分布并定量统计分析其变化特征。结果表明:矿区植被覆盖面积在近十年内持续减少18.539 km 2,塌陷面积共扩大4.379 km 2,而矿区厂矿增加、煤矿开采规模扩大、采煤塌陷区面积扩大以及耕地占用面积增大等人为因素,是威胁大屯矿区生态环境的主要因素。展开更多
文摘Recently land-use change has been the main concern for worldwide environment change and is being used by city and regional planners to design sustainable cities. Nakuru in the central Rift Valley of Kenya has undergone rapid urban growth in last decade. This paper focused on urban growth using multi-sensor satellite imageries and explored the potential benefits of combining data from optical sensors (Landsat, Worldview-2) with Radar sensor data from Advanced Land Observing Satellite (ALOS) Phased Array type L-band Synthetic Aperture Radar (PALSAR) data for urban land-use mapping. Landsat has sufficient spectral bands allowing for better delineation of urban green and impervious surface, Worldview-2 has a higher spatial resolution and facilitates urban growth mapping while PALSAR has higher temporal resolution compared to other operational sensors and has the capability of penetrating clouds irrespective of weather conditions and time of day, a condition prevalent in Nakuru, because it lies in a tropical area. Several classical and modern classifiers namely maximum likelihood (ML) and support vector machine (SVM) were applied for image classification and their performance assessed. The land-use data of the years 1986, 2000 and 2010 were compiled and analyzed using post classification comparison (PCC). The value of combining multi-temporal Landsat imagery and PALSAR was explored and achieved in this research. Our research illustrated that SVM algorithm yielded better results compared to ML. The integration of Landsat and ALOS PALSAR gave good results compared to when ALOS PAL- SAR was classified alone. 19.70 km2 of land changed to urban land-use from non-urban land-use between the years 2000 to 2010 indicating rapid urban growth has taken place. Land-use information is useful for the comprehensive land-use planning and an integrated management of resources to ensure sustainability of land and to achieve social Eq- uity, economic efficiency and environmental sustainability.
文摘数据驱动的多元化发展导致数据异构性增强、维度提升和特征量规模扩大,给贸易经济分析带来更大挑战。为了提高贸易经济分析的科学性,采用非平行超平面支持向量机算法(support vector machine,SVM)对贸易经济进行预测分析。首先,根据贸易经济影响因素进行主成分分析,获取影响贸易经济的关键特征,并对特征进行量化和去噪处理。然后,采用广义特征值最接近支持向量机(proximal support vector machine via generalized eigenvalues,GEPSVM)进行贸易经济预测分类。根据预测指标要求,选择核函数GEPSVM算法(KGEPSVM算法)对分类的非平行超平面求解,通过类别划分函数获得经济预测结果。实证分析表明,对比常用的非平行超平面支持向量机算法,所提算法的贸易经济预测性能更优,而且在常用贸易经济指标的预测中,表现出较高预测精度和稳定性。
文摘矿区土地覆盖变化信息的高精度提取,是区域资源环境保护和地质灾害防治领域的关键问题。以SPOT-5高分辨率卫星影像为数据源,以分类后比较法为变化信息提取方法,利用分类性能良好的支持向量机(SVM)为分类算法,分别设置不同SVM核函数及参数对实验样区进行分类,并评价分析不同核函数及参数对分类效果的影响。实验发现在4种核函数中高斯核函数分类精度最高,为87.1%;Sigmoid和多项式核函数分类精度适中,线性核函数分类精度最低,为78.7%。因此,利用高斯核函数分别对3个时相的大屯矿区影像进行分类,提取出变化信息空间分布并定量统计分析其变化特征。结果表明:矿区植被覆盖面积在近十年内持续减少18.539 km 2,塌陷面积共扩大4.379 km 2,而矿区厂矿增加、煤矿开采规模扩大、采煤塌陷区面积扩大以及耕地占用面积增大等人为因素,是威胁大屯矿区生态环境的主要因素。
