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At the end of the lesson, the student learn.....
1. Basic Geographic Concepts
2. Function of GIS
3. Spatial Analysis
4. GIS Concepts
Basic Geographic Concepts
Listed here are the basic geographic concepts for geographic understanding and inquiry.
Geographic Concepts
Basic geographic concepts are:
Place (physical and cultural attributes)
Density, Dispersion, Pattern
Spatial Interaction
Size and Scale
Location can be described in two ways: absolute and relative and answers the question of “Where is it?” Absolute describes the position of a feature or event
in space, using some form of geographic coordinates. Relative uses descriptive text to describe the position of the feature or event in relationship to another
object or event.
*What is the distance and direction of a place from another? For example, the hurricane will hit landfall 30 miles north of Town A. Understand the location of
features or events is the building blocks to geographic study, including using GIS for mapping and analysis.
Regions are groupings of geographic information. A region is a geographic area defined by one or more distinctive characteristics. Regions can be based on
physical features (such as a watershed), political boundaries (a county, country, or continent), culture or religion, or other categorized geographies. Regions
can be formal, functional, or perceptual. Formal regions are also known as homogenous or uniform region. Entities within a formal region share one or more
common traits such as the residents of a country. a functional region is a region anchored by a focal point.
*Examples are a customer service area for a restaurant delivery service or the school district for an elementary school. A vernacular region (also known as a
popular or perceptive region) is a geographic area that exists as part of a cultural or ethnic identity and therefore don’t adhere to political or formal regional
Place looks at the physical and/or cultural attributes of a place is important. Physical characteristics include: weather and temperature, land and soil, and plant
and animal life. Cultural attributes include: languages, religions and ethnicities, where and how people settle, transportation, economics, and politics.
Density, Dispersion, Pattern
Understanding spatial pattern is an important aspect of geographic inquiry. Spatial pattern looks at commonality in geography across regions. How are things
arranged? Is the arrangement regular? Is there a pattern to the distribution?
Spatial Interaction
Spatial interaction is the cause and effect of an event in one region or area that affects another area and takes a look at the connectivity and relationships of
features. For example, a change in land use from rural to high density can affect traffic congestion in adjoining areas. The 1980 eruption of Mount Saint Helen
affected an area far beyond the volcanic site with ash fallout reach across several states.
*Geographic features are visualized using a map which is a representation of reality. The size and scale affects the degree of generalization of the features
being mapped. The smaller the scale, the less detail is shown. In other words, a small scale shows a larger geographic area (e.g. a map of the world or of a
continent) but shows more generalized features and less detail (e.g. only major highways and major rivers). A large scale map shows a smaller geographic
area (e.g. a map of a city or a neighborhood) but shows a greater amount of detail (e.g. the entire street network and all branches of a river).
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
That’s what’s in a particular place.
*First, you must define the specific location of an object or region information, commonly used definition methods are: determine the location through various
interactive means, or directly input a coordinate; second, after specifying the location of the target or region, you can get the expected results and all or part of
their characteristics, such as the current plot 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
In order to accomplish the core tasks of the above GIS, different functions are needed to implement them. Although the advantages and disadvantages of
commercial GIS software packages are different, and the technologies they use to implement these functions are different, most commercial GIS software
packages provide the following functions: Data Acquisition, Preliminary data Processing, Storage and Retrieval, Search and Analysis, 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 the acquisition of data from observations in the real world, as well as from existing documents 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 the actual results. In the whole process of processing,
data storage and retrieval as well as interactive performance support are needed. In other words, these two functions run through the whole process
Overview of GIS functions (ellipses) and their representation (rectangles)
Six components of spatial information processing and analysis
Spatial operations, such as map union, intersection, subtraction, buffer calculation, selection, etc.
Spatial statistical analysis is used to describe and analyze the relationship between spatial data, such as spatial autocorrelation analysis.
Spatial model, focusing on spatial phenomena, spatial structure, spatial relations and spatial location analysis, such as network analysis and water
system generation, etc.
Spatial representation/visualization, focusing on the expression of spatial information;
Spatial database management, including spatial database design, spatial data structure, spatial data management and spatial query.
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 integrity of data in the GIS database in terms of content and space, numerical logic consistency and correctness.
In general, the construction of a GIS database accounts for 70% or more of the total system construction investment, and this ratio will not change significantly
in the near future.
*Therefore, information sharing and automated data input have become an important part of GIS research; at present, there are many methods and technologies
that can be used for GIS data collection, and some are only used for geographic information systems, such as hand-held tracking digitizers;
Data processing
The data processing of the steps mainly includes data formatting, conversion, and generalization. The formatting of data refers to the transformation between
data of different data structures, which is a time-consuming, error-prone, and requires a large amount of computation, and should be avoided as much as
possible; data conversion includes data format conversion, data scale change, etc. In the way of data format conversion, vector to raster conversion is faster
and simpler than its inverse operation. The transformation of the data scale involves the scaling of the data scale, translation, rotation, etc., the most important
of which is the projection transformation; generalization includes data smoothing, feature aggregation, etc.
*At present, the data summary function provided by GIS is extremely weak, and there is still a big gap between the requirements of map synthesis and further
Data storage and organization
This is a key step in the establishment of a GIS database, involving the organization of spatial data and attribute data. Raster models, vector models, or
raster/vector hybrid models are commonly used methods of spatial data organization. The choice of spatial data structure determines the function of data and
analysis that the system can perform to a certain extent; in the organization and management of geographic data, the most important thing is how to integrate
spatial data with attribute data.
*At present, most systems store the two separately and connect them through common items (generally defined as feature identifiers). The disadvantage of
this organization is that the definition of data is separated from the data operation, and it is impossible to effectively record the changing properties of the feature
in the time domain.
Spatial query and analysis
Spatial query is the most basic analytical function that GIS and many other automated geographic data processing systems should have; spatial analysis is the
core function of geographic information system, and it is also the fundamental difference between geographic information system and other computer systems,
model analysis is to analyze and solve the space-related problems in the real world with the support of geographic information system, which is an important
indicator of the deepening of GIS applications. The spatial analysis of geographic information systems 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 retrieve the required information from large-scale GIS database effectively will affect the analysis ability of GIS; on the
other hand, the graphical expression 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 is the analysis of spatial models within GIS, which attempts to use GIS software to provide spatial analysis modules and develop a macro language
for problem solving models, this method is generally based on the complexity and diversity of spatial analysis and is easy to understand and apply, however,
the spatial analysis functions provided by GIS software are very limited, this tightly coupled spatial model analysis method is less used in the design of actual
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 in the form of either computer screen display
or hard copy maps such as reports, tables and maps, especially the map output function of GIS. A good geographic information system should provide a good,
interactive mapping environment for users of GIS to design and produce high quality maps.
What is spatial thinking?
Search Google Images for 'world maps' and you will be presented with a wide-ranging selection of maps that represent the world. Many of these images will
have been manipulated for a purpose. Save a collection of these images and use them with your students to help develop their critical map literacy. (Please
respect copyright law and do not distribute these images outside your classroom unless permission is expressly given on the websites where you obtained
Digital mapping
Geospatial technologies, such as Google Earth and GIS, are examples of high-tech systems that can help students become spatially literate. Refer to Geospatial
technologies (including GIS).
Such technologies enable students to ask five important questions that have been described as ‘spatial querying’:
Manipulating digital maps allows you to change them in many different ways. Developing spatial thinking is taking on new layers of complexity as technology
is literally changing the shape of maps as we know them. Danny Dorling comments, ‘On our screens, on our phones, in our textbooks and magazines, our
images of the world are changing faster than the world is itself.’ (2012). He has spent over 25 years drawing what he describes as strangely shaped maps.
Browse www.worldmapper.org which is a collection of world maps, with variables from refugees to house prices, where territories are re-sized on each map
according to the subject. Worldmapper was developed in 2006 and relaunched in 2018. There are now nearly 700 maps to explore and they give powerful
visual impact to current patterns in development.
Spatial analysis
Is a type of geographical analysis which seeks to explain patterns of human behavior and its spatial expression in terms of mathematics and geometry, that is,
locational analysis.
*Examples include nearest neighbor analysis and Thiessen polygons. Many of the models are grounded in micro-economics and predict the spatial patterns
which should occur, in, for example, the growth of networks and urban systems, given a number of preconditions such as the isotropic plain, movement
minimization, and profit maximization. It is based on the tenet that economic man is responsible for the development of the landscape, and is therefore subject
to the usual criticisms of that concept, such as the lack of free will.
New methodologies of spatial analysis include geocomputation and spatial statistical theory.
GIS Concepts
What can we do with GIS?
GIS can be used as tool in both problem solving and decision making processes, as well as for visualization of data in a spatial environment. Geospatial data
can be analyzed to determine (1) the location of features and relationships to other features, (2) where the most and/or least of some feature exists, (3) the
density of features in a given space, (4) what is happening inside an area of interest (AOI), (5) what is happening nearby some feature or phenomenon, and
(6) and how a specific area has changed over time (and in what way).
Mapping where things are. We can map the spatial location of real-world features and visualize the spatial relationships among them. Example:
below we see a map of frac sand mine locations and sandstone areas in Wisconsin. We can see visual patterns in the data by determining that frac
sand mining activity occurs in a region with a specific type of geology.
Mapping quantities.People map quantities, such as where the most and least are, to find places that meet their criteria or to see the relationships
Example: below is a map of cemetery locations in Wisconsin. The map shows the cemetery locations as dots (dot density) and each county is color
Mapping densities.Sometimes it is more important to map concentrations, or a quantity normalized by area or total number. Example: Below we
have mapped the population density of Manhattan (total population counts normalized by the area in sq. miles of census tracts.).
is happening or what features are located inside a specific area/region. We can
4. Finding what is inside. We can use GIS to determine what
determine the characteristics of "inside" by creating specific criteria
to define an area of interest (AOI). Example: below is a map showing a flood event and the tax parcels and buildings in the floodway. We can use tools like
CLIP to determine which parcels fall inside the flood event. Further, we can use attributes of the parcels to determine potential costs of property damage.
Finding what is nearby. We can find out what is happening within a set distance of a feature or event by mapping what is nearby using geoprocessing
tools like BUFFER. Example: below we see a map of drive times from a central location in the City of Madison, WI. We can use streets as a network
and add specific criteria like speed limit and intersection controls to determine how far a driver can typically get in 5, 10, or 15 minutes. (Map courtesy
of UW Extension)
Mapping change. We can map the change in a specific geographic area to anticipate future conditions, decide on a course of action, or to evaluate
the results of an action or policy. Example: below we see land use maps of Barnstable, MA showing changes in residential development from 1951
to 1999. The dark green shows forest, while bright yellow shows residential development. Applications like this can help inform community planning