تحميل كتاب مقدمة في نظم المعلومات الجغرافية Introduction To Geographic Information Systems GIS

تحميل كتاب مقدمة في نظم المعلومات الجغرافية Introduction To Geographic Information Systems GIS ، استكمالا لسلسلة تعلم GIS نقدم لكم في هذه المقالة كتاب مقدمة في نظم المعلومات الجغرافية Introduction To Geographic Information Systems GIS ، من تأليف Kang-tsung Chang .

Introduction book Introduction To Geographic Information Systems GIS

A geographic information system (GIS) is a computer system for capturing, storing, querying, analyzing, and displaying geospatial data. One of many applications of GIS is disaster management.

• CHAPTER ELEMENTS:

- GIS

- Elements of GIS

- Applications of GIS

- Integration of GIS, Web2.0, and Mobile

- Technology

- Organization of This Book

- Concepts and Practice

A basic principle in geographic information system (GIS) is that map layers to be used together must align spatially. Obvious mistakes can occur if they do not. For example, Figure 2.1 shows the interstate highway maps of Idaho and Montana downloaded separately from the Internet. The two maps do not register spatially. To connect the highway networks across the shared state border, we must convert them to a common spatial reference system. Chapter 2 deals with coordinate systems, which provide the spatial reference.

• CHAPTER ELEMENTS:

- Geographic Coordinate System

- Map Projections

- Commonly Used Map Projections

- Projected Coordinate Systems

- Options for Coordinate Systems in GIS

Looking at a paper map, we can tell what map features are like and how they are spatially related to one another. For example, we can see in Figure 3.1 that Idaho is bordered by Montana, Wyoming, Utah, Nevada, Oregon, Washington, and Canada, and contains several Native American reservations. How can the computer “see” the same features and their spatial relationships? Chapter 3 attempts to answer the question from the perspective of vector data.

The vector data model, also called the discrete object model, uses discrete objects to represent spatial features on the Earth’s surface. Based on this concept, vector data can be prepared in three basic steps. The first step classifies spatial features into points, lines, and polygons over an empty space and represents the location and shape of these features using points and their x-, y-coordinates. The second step structures the properties and spatial relationships of these geometric objects in a logical framework. Most changes for the past three decades have been related to the second step, reflecting advances in computer technology and the competitive nature of the geographic information system (GIS) market. The third step codes and stores vector data in digital data files so that they can be accessed, interpreted, and processed by the computer. The computer recognizes the format of the data files (i.e., how data are structured

and stored) by their extension.

• CHAPTER ELEMENTS:

- Representation of Spatial Features

- Topology

- Georelational Data Model

- Object-Based Data Model

- Representation of Composite Features

The vector data model uses the geometric objects of point, line, and polygon to represent spatial features. Although ideal for discrete features with well-defined locations and shapes, the vector data model does not work well with spatial phenomena that vary continuously over the space such as precipitation, elevation, and soil erosion (Figure 4.1).

A better option for representing continuous phenomena is the raster data model, also called the

field-based model. The raster data model uses a regular grid to cover the space. The value in each grid cell corresponds to the characteristic of a spatial phenomenon at the cell location. And the changes in the cell value reflect the spatial variation of the

phenomenon.

• CHAPTER ELEMENTS:

- Elements of the Raster Data Model

- Satellite Images

- Digital Elevation Models

- Other Types of Raster Data

- Raster Data Structure

- Raster Data Compression

- Data Conversion and Integration

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