中文摘要：

合理的配置公共服务设施对城市的现代化建设至关重要。空间可达性是度量公共服务设施配置是否合理的方法之一。在诸多的研究方法中,高斯两步移动搜索法由于直观且运算简便,因而得到广泛应用。但该方法也有不足之处,本文运用格网GIS方法,以上海市的绿地空间可达性为例,对两步移动搜索法进行模型方法的改进研究,并对高斯两步移动搜索法和格网化的高斯两步移动搜索法进行对比分析,结果表明：后者可降低空间可达性的误差,提高可达性精度,对上海市绿地空间可达性反映更加真实、客观。如果选择合理的数据将其格网化,该方法也可以用于其他公共服务设施的空间可达性研究。

英文摘要：

In recent years, urban public service facilities have increased rapidly. Spatial accessibility measurement can be applied to assess the soundness of public service facilities distribution. Among various kinds of methods, the Gaussian based 2-step floating catchment area （2SFCA） method is relatively straightforward, and the greatest strength of the method is that it overcomes the restriction of using only pre- defined regional boundaries. Therefore it is most widely used. However, further research is needed to improve its accuracy. Many recent improvements to the 2-step floating catchment area method generally account for distance-decay within a catchment or enable the usage of variable catchment sizes. In order to improve the method, this study conducted a case study of green space accessibility analysis for the city of Shanghai using the census data of 2000 and 2010 and raster GIS analysis. The result was compared to the original 2-step floating catchment area method output. The results show that the raster Gaussian based 2-step floating catchment area method is a more precise method than the Gaussian based 2-step floating catchment area method for measuring the spatial accessibility to green space. A map of spatial accessibility was developed to show the geographic distribution of spatial accessibility to green space in Shanghai. Spatial accessibility is higher in the peri-urban part as compared to the central part of the city. The raster Gaussian based 2-step floating catchment area method can reduce the error of Kriging spatial interpolation. In the Gaussian based 2-step floating catchment area method the result is expressed as values at the center points of streets and these values are discrete. But in the raster Gaussian based 2-step floating catchment area method the green space accessibility of a point in the space is computed for the grid cell. Thus the raster Gaussian based 2-step floating catchment area method is more precise than the Gaussian based 2-step floating catchment area method. Also, the