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

1) Locations

That is, what is at a specific location.

First, the specific location of an object or regional information must be defined. Common methods for defining location include determining positions through various interactive means or directly inputting coordinates. Second, after specifying the location of a target or area, expected results and all or part of its characteristics can be obtained, such as current land parcel owner, address, land use status, valuation, etc.

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 conditions, a list of all objects meeting the specified criteria can be obtained, such as highlighting all features on the screen that satisfy the given conditions. For example, houses located in residential areas, valued below $200,000, with four bedrooms, and constructed of wood.

3) Trends

This type of problem requires the integration of existing data to identify geographical phenomena that have already occurred or are undergoing changes.

First, identifying trends, though determining trends cannot, of course, guarantee correctness every time. Once a specific dataset is mastered, identifying trends may rely on assumptions, personal speculation, observed phenomena, or reported evidence.

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. 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.

To accomplish the aforementioned core tasks of a Geographic Information System, various functions need to be employed. Despite variations in the strengths and weaknesses of commercial GIS software packages and the differing technologies they use to implement these functions, most provide the following capabilities:

• Data Acquisition

• Preliminary data Processing

• Storage and Retrieval

• Search and Analysis

• Display and Interaction

Figure 1-8 illustrates the relationships between these functions and their different manifestations in data manipulation.

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.

** 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.