Overview of the functions of GIS

Release date:2021-12-15 Update date:2023-08-23 Editor:admin View counts:3906


Overview of the functions of GIS

The core issues of geographic information system can be summarized into five aspects: location, conditions, trends, patterns and models.

1) Locations (Locations)

That’s what’s in a particular place.

First of all, the specific location of an object or area information must be defined, and the common definition methods are: determining the location through various interactive means, or directly entering a coordinate; second, after specifying the location of the target or area, you can obtain the expected results and all or some of its characteristics, such as the current parcel owner, address, land use, valuation, and so on.

2) Conditions

That is, where there is something that meets certain conditions.

First, you can specify a set of conditions, such as selecting from predefined options; filling in logical expressions; and interactively filling in forms on terminals.

Secondly, after specifying the conditions, you can get a list of all the objects that meet the specified conditions, such as showing all the features that meet the specified conditions on the screen with high brightness, such as the land type in which it is located, the valuation is less than $200,000, four bedrooms and a wooden house.

3) Trends

Such problems need to integrate existing data in order to identify geographical phenomena that have occurred or are changing.

First of all, to determine trends, of course, the determination of trends does not guarantee that each time is correct, once a specific data set is mastered, the determination of trends may depend on hypothetical conditions, personal speculation, observation phenomena or evidence reports.

Secondly, in view of this trend, we can confirm or negate it by analyzing the data. Geographic information systems allow users to quickly obtain quantitative data and charts illustrating the trend. For example, through GIS, the characteristics of this trend can be identified: how many citrus plots have been converted to other uses? What’s the use now? How many such changes have taken place in a region? How many years can this change be traced back? Which time period best reflects this trend? One year, five years or ten years? Has the rate of change increased or decreased?

4) Patterns

Such problems are related to the analysis of events that have occurred or are occurring. Geographic Information System (GIS) combines existing data to better explain what is happening and find out which data is relevant to what happened.

Firstly, the determination of patterns usually requires long-term observation, familiarity with existing data and understanding of the potential relationship between data.

Secondly, after the mode is determined, a report can be obtained showing when and where the event occurred and a series of maps showing the event. For example, motor vehicle accidents often conform to a specific pattern, where does the pattern (accident) occur? Does the place of occurrence have anything to do with the time? Is it at a particular intersection? What are the conditions at these intersections?

5) Models

The solution of this kind of problem needs to establish a new data relationship to produce a solution.

Firstly, models are established, such as selection criteria, testing methods, etc.

Secondly, after establishing one or more models,which can generate a list that satisfies all the specific features, emphasizing the map of the selected features, and providing a detailed description of the selected features. For example, to build a children’s bookstore, the evaluation indicators for site selection may include 10, 15, 20 minutes of reachable space. The number of children aged 10 or under living nearby, the income of nearby families and potential competition around them.

In order to accomplish the core tasks of the above-mentioned geographic information system, different functions need to be used to achieve them. Although the advantages and disadvantages of current commercial GIS packages are different, and the technologies they use to implement these functions are also different. However, most commercial GIS software packages provide the following functions: data acquisition (Data Acquisition), preliminary data processing (Preliminary data Processing), data storage and retrieval (Storage and Retrieval), data query and analysis (Search and Analysis), graphic display and interaction (Display and Interaction).

Figure 1-8 illustrates the relationship between these functions and the different representations of their Manipulation data.

As can be seen from figure 1-8, data acquisition is obtained from real-world observations, as well as from existing files and maps. Some data are already in digital form, but data preprocessing is often needed to convert the original data into structured data so that it can be queried and analyzed by the system. Query analysis is to obtain a subset of data or transform it, and interact with real results. In the whole processing process, we need the support of data storage and retrieval and interactive performance, in other words, these two functions run through the GIS data processing all the time.


Fig. 8 Overview of GIS functions (ellipses) and their representation (rectangles)

** Six components of spatial information processing and analysis [Ding Yuemin]**

  1. Spatial operations, such as map union, intersection, subtraction, buffer calculation, selection, etc.

  2. Spatial statistical analysis is used to describe and analyze the relationship between spatial data, such as spatial autocorrelation analysis.

  3. Spatial model, focusing on spatial phenomena, spatial structure, spatial relations and spatial location analysis, such as network analysis and water system generation, etc.

  4. Spatial representation/visualization, focusing on the expression of spatial information;

  5. Spatial database management, including spatial database design, spatial data structure, spatial data management and spatial query.

  6. Spatial model base management, including model management for spatial decision support system, etc.

Data collection, monitoring and editing

It is mainly used to obtain data to ensure the content and spatial integrity, numerical logic consistency and correctness of the data in the GIS database. Generally speaking, the construction of GIS database accounts for 70% or more of the investment in the construction of the whole system, and this proportion will not change significantly in the near future. Therefore, information sharing and automatic data input have become an important part of GIS research. At present, there are many methods and techniques that can be used for GIS data acquisition, some of which are only used in GIS, such as hand tracking digitizer. At present, automatic scanning input and remote sensing data integration are the most concerned. The application and improvement of scanning technology and the realization of automatic editing and processing of scanning data are still the main technical keys of GIS data acquisition research.

Data processing

The preliminary data processing mainly includes data formatting, transformation and generalization. Data formatting refers to the transformation between different data structures, which is time-consuming, error-prone and requires a large amount of calculation, which should be avoided as much as possible; data conversion includes data format transformation, changes in data scale and so on. In the conversion mode of data format, the conversion from vector to grid is faster and simpler than its inverse operation. The transformation of data scale involves data scale scaling, translation, rotation and other aspects, of which the most important is projection transformation; cartographic generalization (Generalization) includes data smoothing, feature aggregation and so on. At present, the function of data generalization provided by GIS is very weak, and there is still a big gap with the requirements of map synthesis, so it needs further development.

Data storage and organization

This is a key step in the establishment of GIS database, which involves the organization of spatial data and attribute data. Raster model, vector model or raster / vector hybrid model are commonly used methods of spatial data organization. To a certain extent, the choice of spatial data structure determines the function of data and analysis that the system can perform; in the organization and management of geographic data, the most important thing is how to integrate spatial data and attribute data. At present, most systems store the two separately and connect them through common items (generally defined as figure identification codes). The disadvantage of this kind of organization is that the definition of the data is separated from the data operation, so it can not effectively record the change attributes of the ground objects in the time domain.

Spatial query and analysis

Spatial query is the most basic analysis function that GIS and many other automatic geographic data processing systems should have. Spatial analysis is not only the core function of GIS, but also the fundamental difference between GIS and other computer systems. model analysis is to analyze and solve space-related problems in the real world with the support of GIS. It is an important symbol of deepening the application of GIS. The spatial analysis of GIS can be divided into three different levels.

Spatial retrieval

It includes retrieving spatial objects and their attributes from spatial locations and retrieving spatial objects from attribute condition sets. “Spatial index” is the key technology of spatial retrieval, how to effectively retrieve the required information from large GIS databases will affect the analytical ability of GIS; on the other hand, the graphic representation of spatial objects is also an important part of spatial retrieval.

Spatial topology overlay analysis

Spatial topology overlay realizes the union of input element attributes and the spatial connection of element attributes. The essence of spatial topological superposition is Boolean operation in spatial sense.

Spatial model analysis

In terms of spatial model analysis, most of the current research work focuses on how to combine GIS with spatial model analysis. Its research can be divided into three categories:

The first is the spatial model analysis of the external geographic information system, which regards the geographic information system as a general spatial database, while the spatial model analysis function relies on other software.

The second category is the spatial model analysis within GIS, which attempts to use GIS software to provide spatial analysis modules and develop macro languages suitable for problem-solving models. this method is generally based on the complexity and diversity of spatial analysis and is easy to understand and apply, but the function of spatial analysis provided by GIS software is very limited. This closely integrated spatial model analysis method is rarely used in the design of practical geographic information systems.

The third type is the hybrid spatial model analysis, which aims to make the best use of the functions provided by GIS and give full play to the initiative of users of GIS.

Graphic and interactive display

Geographic Information system (GIS) provides users with many tools for the representation of geographic data, which can be in the form of computer screen display or hard-copy maps such as reports, tables, maps and so on. special emphasis should be placed on the map output function of GIS. A good geographic information system should be able to provide a good and interactive mapping environment for GIS users to design and produce high-quality maps.

  • 1. Geographical Cognition of the Real World
  • 2. The abstraction of the real world
  • 3. Bit world
  • 1. Data meaning and data type
  • 2. Measurement scale of data
  • 3. GIS data quality
  • 4. Metadata of spatial data
  • 1. Map digitization
  • 2. Processing of spatial data entry
  • 1. Socialization of GIS
  • 2. Other problems of GIS socialization
  • 3. The impact of society on the development of GIS

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