tailieunhanh - Geographic Information Management in Local Government - Chapter 2

Sự phát triển của GIS trong chính quyền địa phương Những phương pháp được sử dụng để xử lý dữ liệu không gian trước khi GIS? Những người tiên phong đầu tiên của GIS là ai? Báo cáo Chorley là gì và tác động của nó là những gì? Đến mức độ nào đã làm báo cáo Chorley dẫn đến sự phát triển phối hợp của GIM trong chính quyền địa phương? GIS lây lan như thế nào thông qua chính quyền địa phương trong những năm 1990? Những gì tiến bộ đã được thực hiện mười năm sau khi báo. | CHAPTER 2 The Development of GIS in Local Government KEY QUESTIONS AND ISSUES What methods were used for handling spatial data before GIS Who were the early pioneers of GIS What was the Chorley report and what was its impact To what extent did the Chorley report lead to the coordinated development of GIM within local government How has GIS spread through local government during the 1990s What progress had been made ten years after the Chorley report How has the modernizing government agenda affected GIS development What lessons can be learned from this review of GIS development WHAT METHODS WERE USED FOR HANDLING SPATIAL DATA BEFORE GIS Before computers were commonly available in local authorities maps were the main means of handling GI. They were used in a whole range of applications for example plotting planning applications recording property terriers route finding calculating areas locating new school sites and understanding patterns of crime and accidents. In fact maps were so important that a wide variety of professions working within local government could not exist without them. Sieve mapping a technique combining several map layers on a light table to identify areas of overlay and interest was particularly important in handling spatial data. But paper maps have their own well-known limitations they stretch and shrink they are always out of date they often require complete redrawing for minor changes they need considerable storage space they can be easily lost or destroyed and they literally fall apart if in constant use for years. For those interested in environmental and land use information aerial photographs have been valuable sources for many years. While they provided snapshots 2004 by CRC Press LLC of geographic areas at particular instants in time they were expensive to obtain affected by cloud cover and because of poor ground resolution the depicted details were often too coarse for most local government activities. However because they involve