tailieunhanh - Geographic Information Management in Local Government - Chapter 4

Không gian dữ liệu Các đặc điểm chính của dữ liệu không gian là gì? Các loại chính và các nguồn dữ liệu không gian là gì? Một mô hình dữ liệu là gì và làm thế nào là dữ liệu không gian mô hình? Phương pháp thu thập dữ liệu có sẵn? Những loại cơ sở dữ liệu được sử dụng trong GIM và tại sao họ lại quan trọng đến như vậy? Tại sao là chất lượng dữ liệu quan trọng và làm thế nào để chúng ta đạt được điều đó? Những phân tích được thực hiện trên. | CHAPTER 4 Spatial Data KEY QUESTIONS AND ISSUES What are the main characteristics of spatial data What are the main types and sources of spatial data What is a data model and how is spatial data modeled What methods of data capture are available What types of databases are used in GIM and why are they so important Why is data quality important and how do we achieve it What analyses are typically carried out on spatial data How do models of spatial processes help decision making What are the main forms of GIS output WHAT ARE THE MAIN CHARACTERISTICS OF SPATIAL DATA GIS are simplified computer representations of reality. The data they use are typically observations and measurements made from monitoring and recording the world around us. However capturing the appropriate data can be a daunting and time-consuming task. Although there are many sources there are basically only two categories primary data collected through first-hand observation and secondary data collected by another individual or organization. All data typically have three dimensions relating to their location where they are their attributes what they are and the date when they were collected. GIM places the greatest emphasis on using the locational or spatial element for transforming data into information thereby giving it meaning. As we have seen already the traditional way of storing analyzing and presenting spatial data is the map. Cartographic methods are centuries old and there are many similarities between their approach and the theoretical framework for GIS. Hence there is a great deal to learn from the cartographer s approach not least that the purpose of the map 2004 by CRC Press LLC decides the features to select and defines the amount of generalization the spatial referencing system and the method of representing of the data. During the mapping process the cartographer must Establish the purpose the map is to serve Define the scale at which the map is to be produced Select the features .