Abstract: In this paper, using the urban night light to simulate the distribution and expansion of urban, during the last 21 years in Chengdu and Chongqing area. The night light image processing is divided to three steps：Mutual correction, contrast filter segmentation and gray threshold classification. The urban area is extracted from the image, and the extraction accuracy is assessed using area ration method. Through the Geo-Spatial Analyst, combined with the transportation net to monitor the direction and structure of urbanization in Chengdu and Chongqing area, the results show that：（1）The combination of contrast filter segmentation and gray threshold classification improve the accuracy of classification and the [An] is 0.052. （2）The urban expansion show the different characteristics between Chengdu and Chongqing. Chengdu and adjacent areas mainly presented in Mianyang - Chengdu - Leshan as the main axes, and expansion direction is north-east and south-west, the urban extended range increased significantly from 2003 year. The direction of expansion of Chongqing is north-west and toward Chengdu. （3）The expansion structure of Chongqing is star style. While, Chengdu and its adjacent area have the ring style, containing the outer ring of Chengdu, Pengzhou-Lezhi-Zhongjiang-Meishan-Dujiangyan and Mianyang-Suining-Neijiang-Zigong-Leshan.

Key words: Chengdu and Chongqing region, DMSP/OLS image, contrast filter segmentation, urbanization monitoring

摘要： 成渝地区快速城镇化的背景下，利用该地区夜晚灯光的分布和亮度变化来模拟区域城市扩展情况。对近21年的DMSP/OLS夜光遥感数据的相互定标、梯度分割、灰度阈值分类，提取出城市空间分布，同时采用面积比值法进行提取精度评估。基于Geo-Spatial Analyst模块对成渝地区城市分布的矢量图形进行空间叠加分析，结合该区域的交通网，来监测区域城市化进程和城市结构的变化，研究结果表明：梯度分割和灰度阈值分类的组合方式，提高了对图像城市区的识别精度，精度[An]达到了0.052；成渝双核城市化扩展呈现不同特点，成都以及毗邻区主要呈现以绵阳—成都—乐山为主轴的东北西南向扩展特点，从2003年以后开始，该地区城市扩展范围增加明显。而重庆地区则是重庆为内核向四周扩展；成都和重庆的城市扩展呈现了独特的扩展结构，成都及其毗邻区呈现以成都外环、彭州-乐至-中江-眉山-都江堰、绵阳-遂宁-内江-自贡-乐山，的三环卫星城网络结构。而重庆的扩展结构呈现星型，以重庆为中心向外辐射，辐射方向主要是西北和西南。

关键词: 成渝地区, 夜光遥感图像, 梯度分割, 城市化监测