Introduction To Geospatial Information Technology
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Introduction to Geospatial Information Technology Video File: Introduction to Geographical Information System
The purpose of this module is to introduce you to the concepts of GIS. You will learn basic information that will be required to successfully complete the case studies required for this class. You may have used services like Google Earth (if you have not you really need to install it http://earth.google.com) or other web based maps. You may have used a GPS (Global Positioning Satellite System) when you hike or drive your car. It is assumed that you have never attempted to construct a map; it is also assumed that this class will serve as your first real GIS experience using professional mapping software. In this course you will use ESRI ArcMap software, you can use ArcView, ArcEditor or ArcInfo, it must be the current version of the software. The software will be made available to you.
Before you begin creating maps you first need to understand about the coordinate system and projections of the earth’s surface.
Geographical Coordinate and Projections The web link for content is located at:
Figure 1 Earth Projection
http://techcenter.jefferson.kctcs.edu/RS/topics/coordinates/Pages/default.aspx. When we create a map it in general is a two dimensional surface, but the earth is a three-dimensional object that both appears as Introduction to Geospatial Information Technology 1 a ball (not exactly a sphere), but also has elevation changes such as mountains. Therefore, it requires mathematical models that project the earth surface onto a two dimensional surface. There are multiple different types of projections in this course we want you to understand some of the basic information about projects. You will not be required to do any mathematical calculation on projects and coordinates, as the software used will accomplish these tasks. If data is not projected it cannot be displayed and two different datasets may not align properly. You also need to understand about coordinate systems, we must be able to locate objects on the surface of the earth and thus on your maps, just as in mathematics we locate points on a graph using an x and y coordinate system. You may be familiar with the latitude and longitude system. Lines of latitude run parallel to the equator from 0 to 90 degrees north of the equator and 0 to 90 degrees south of the equator. Lines of longitude run perpendicular to the lines of latitude. They are measured east and west of the prime meridian (0 degree longitude). They are measured from 0 to 180 degrees east longitude and 0 to 180 degrees west longitude. This system is very useful and note that it uses degree measurements, with one degree composed of 60 minutes of arc and one minute composed of 60 seconds of arc. You may need to convert the Figure 2 Earth Projection minutes and seconds into digital fractional degrees to make the numerical calculations easy to utilize. There are other systems that are used with different units such as feet and meters. When data is in different units that can effect how the data is displayed. There are other x,y coordinate system that uses feet and meters, such as the State Plane system. It is critically important than when data is imported into a map that it is of the same geographical projection as well as the same coordinate systems so that it will be displayed appropriately. ArcMap will attempt to place the data appropriately onto your existing map if there is a defined coordinate system and projection. The defining of coordinate systems will be covered more generally in this course then in Figure 3 Latitude and Longitude more advanced courses.
ArcMap
As stated previously there are multiple versions of ArcMap, but for this course it will be possible to use any of the three versions to complete the introduction and the six case studies. You must have access to the software. Many of the buttons and menus have a standard appearance. Two programs can be started from within ArcMap, Toolbox and ArcCatalog. ArcCatalog is represented by the file cabinet icon
Figure2 4 ArcMapIntroduction Buttons to Geospatial Information Technology (yellow icon) and Toolbox by the red toolbox icon. Both of these programs will be used to complete the requirements of this course.
Basic Map Data Shapefiles
There four major types of data. Data is placed on a map in layers. A layer is like putting pieces of transparent plastic on top of one another. Therefore, if what is drawn on the transparent plastic is opaque it will block anything on other plastic sheets placed below. If the object is a line or data point other information can still be observed. If the object is an aerial photograph nothing below the photograph will be seen. Objects can be made semi-transparent so that you can see through them. Ordering of layers is very important in map construction. Data is classified in one of four types.
A shapefile is not just a single file but requires multiple files that all must be in the same file folder or else they will not work properly. Therefore, when data is shared the entire folder must be shared, thus the best way to share data is in compressed or zipped information. As will be noted later in this module, once you place the data into a file structure it should not be moved because this will affect the ability to display the data appropriately. The screen shot shows three layers and a small portion of a map. The check box tells you if the layer is active or not, in this case all three layers are active. Right Clicking on layer will bring up the property window. There are three types of shapefiles.
Figure 5 Layers
Point data is as it’s name indicates a single Introduction to Geospatial Information Technology 3
Figure 7 Line - Streams region of Kentucky Figure 6 Point Data - Hospitals region of Kentucky point, you can make the point whatever size or color that is appropriate for the map that will be created. In general point date is in the highest layers. Point date might be a building, town, cemetery or any other object that can be represented as a single point, such as the location of student homes. Points might be used for major cities on a U.S. map, but on a county map they might be represented by the actual city boundaries.
Line data represents objects in which the actual width is not specified and is not a closed object. Roads, streams are two of the most common line data shapefiles. If you are looking at a detailed view then the streams and roads would need to have width or if you are looking at a major river such as the Ohio it needs to have width. Polygon data represents a closed object, which can be filled. Objects such as state, county and city boundaries are usually represented by a polygon shapefile. Zip Code areas and Census blocks and tracts are also represented as polygons. When you fill an object with an opaque color you cannot see any data layers below the filled layer. You can make a fill semi-transparent so that you can see data below the layer.
Figure 8 Polygon - Barren County, KY
Raster is a picture, typical an object such as an aerial photograph or a scanned/digitized map. These objects are usually the lowest level on a map. The image must be geo-projected appropriately for it to be displayed. Raster images can also be made semi-transparent. Therefore, the layers in a map generally follow the order listed 4 Introduction to Geospatial Information Technology
Figure 9 Raster - Southern Indiana above with point files being had the highest level and raster images at the lowest level on a map. There are always reasons, which might be done differently, but these are the general norms. A shapefile is a vector quantity, which means the data can be expanded with the same quality as the original. A vector has a length and angle, so as you look at a line for example each segment is really a straight line, and the length of the line and the angle of the segment is the recorded information. Raster images are bitmaps and as you expand beyond the original resolution will become blurred and less clear. Project File
When you create a map it must be saved so that you can edit the content in the future, the file that is saved has an mxd extension. The file does not save your shapefile but only provides a pointer to the location of the content. Therefore once your begin creating a project file you can no longer move the data (shapefiles). If you do move the data it will need to be reassociated before the map can be produced or edited. You will know that data is not properly associated because it will appear to be grayed out instead of black print in the layer area.
If you move your mxd file from one computer to another and the data was stored on your local computer or mapped to a network server this will also cause the data to be disassociated. Using ArcIMS and ArcServers or any Internet based server location can solve some of these issues.
To re-associate the data you first most go to the property window for that layer, by right clicking on the layer. Then click on the source tab and you will need to browse to the location the data is now stored at, which is basically finding the data again. Parameters that you have set such as color will remain active once the data has been re- associated.
Maps can also be stored as a graphic image. Stored in a graphic image format will not allow for Figure 10 Re-associating Data any interaction with the data but will create a static image, that can be used in other applications. Map images can also be stored as a pdf file type (Adobe Acrobat format), which is much like printing a hard copy of the file.
Data Storage Since storing your data in the proper location from the very beginning is important, as discussed previous moving data cause disassociation problems. Therefore the development of a data storage methodology is Introduction to Geospatial Information Technology 5 very important. You should arrange your data by geography (states, counties, etc.) as well as the type of data (point, line, etc.). The method that we use is breaking each geo-political area down into its lowest level of subdivision. If you start with the world, next would be countries, then states, counties and finally cities. Under each of these geo- political divisions we break the data into the different types of shapefiles. In addition to the shapefiles we also have data (excel files, etc.) and compressed files saved in these locations. At times you may need to add a Figure 11 Tree Structure region that does not fit these divisions, for example if you are working with the service area of a college it will extend beyond a single county but not be across the entire state. This data is being stored on a local or network drive. If the data is on a networked drive it needs to be mapped to a drive letter. Another way in which data can be stored is on a geo data base server that has a url, this makes the data accessible from multiple locations and does not require the user to be inside of the network, appropriate permissions can be established. The data can also be stored on an ArcIMS server, which will require the use of additional software to put it into the appropriate format. The data on an ArcIMS server can also be used on the Internet by creating appropriate web pages. Data
Video: Adding Data to a Ma p
There are three main ways in which data can be placed on to a map. You can use the add data button, you can use ArcCatalog or drag and drop a shapefile onto a map.
You can drag any shapefile onto a map and it should display and be placed into the layer window. While this way is functional it is not my recommended way of doing this data placement on a map.
Using the add data button gives you a very straightforward way of adding data but does not give any additional control of the data. It will open explorer type windows and can also add data from server sources. You may need to use the mapping tool, which is the arrow to the right.
6 Introduction to Geospatial Information Technology Figure 12 Adding Data
ArcCatalog is used to load informational data onto a map; it utilizes a file management system. This will include the downloading of information from local and remote sites as well as the attaching to a geo database server. A geoserver is different from downloading data from a traditional web based data server, since the geoserver presents geographically coded information. ArcCatalog is a program that can be launched from within ArcMap. ArcCatalog gives more control over the data, including creating new shapefiles and geodatabases. You will use drag and drop from ArcCatalog to ArcMap.
Introduction to Geospatial Information Technology 7 Figure 13 ArcCatalog
Compressed Data Most of the information that is downloaded will be in a compressed format (zipped). This is particular true when multiple files must be moved together from one user to another. This is very important that you have programs on your computer that can both decompress as well compress the information. For when you wish to share the information with other users you should compress it. There is free software that does this operation very effectively. You must decompress information prior to adding it to the map. The icons used for compressed data will vary from computer to computer depending on what software is installed for decompression. Windows comes with software installed, but many users will install there own decompression software.
8 Introduction to Geospatial Information Technology Properties
Properties give you the ability to display information in a logical format. As you look at the images in Figures 5 through 8 for point, line and polygon information, basic symbology was done on each data set. For the point data the symbol was changed from a diamond (default) to a hospital symbol to better represent the information. On the line image the colors of the rivers and county boundaries were changed to different colors to better Figure 14 Layer Properties describe the information. For the polygon data, the appropriate attribute was chosen as well as the ramp colors and break points. One of the most used tabs in properties is the symbology tab; it gives you the ability to control the data as well as many of the properties related to data display. To reach the property window, remember right click on the layer (shapefile or raster).
Labeling maps Placing labels onto features makes it much easier to understand the map that you are creating, care must be taken not to place too much information onto the map, because the map can become very hard to use. For example if you were looking at a state map in a standard size page size, you most likely would not want to name every city street and you would not want them to even be visible. Like wise you would not want to name every county in the state at this scale, but if you zoom in you might want these items to be appropriately named. This can be set both automatically or done manually.
Introduction to Geospatial Information Technology 9 In addition you want to make sure there is enough information provided on the map that it could be understood without need for additional documentation. Therefore, the map should have a title box that provides information about the map creator and the firm in which they represent. Directional arrows and scale indicators are extremely important as is providing a title to the map. Additional text boxes might be needed to explain the map, especially if it is going to be created in a large format. A legend is also needed to explain the symbols and the colors used in the map creation. Remote Sensing
Remote Sensing is the ability to gather data without direct contact with the area in which the data is being collected. For example when a satellite in orbit around the earth images the earth, this data is received by a satellite receiving station and is then georeferenced so that the data can be used to analyze specific features of the earth. Remote sensing is done both actively and passively. Passive remote sensing is the receiving of information by reflected or emitted electromagnetic wavelengths. This information maybe in the infrared, visible and ultraviolet regions of the spectrum, the information is normally detected by either airplane or satellite. Passive remote sensing is when energy strikes the surface of the earth and the reflected energy is recorded by a sensing platform, such as radar to measure the elevation of the earth’s surface. The study of remote sensing is beyond the scope of this class in general, to learn more about remote sensing you can take a complete course introductory course. Some content from the remote sensing class will be utilized in this course and some of the referenced material for content is located on the remote sensing course. For additional information: http://techcenter.jefferson.kctcs.edu/RS Report Creation
While creating the maps is a very important part of GIS, it is not the sole job of a geospatial specialist. The specialist must also provide written assessment of what was discovered through the geospatial research. Maps need to be integrated into the report as well as graphs and data tables. This information provides the foundations for the creation of the analysis of the information. Basic word processing, spreadsheet creation and database usage are also required to successful analyze the information to fully understand the material given and the conclusions drawn. Microsoft Office does a very good job, if you do not have it, you can use Google Docs (http://docs.google.com) or Open Office (http://www.openoffice.org), or Zoho (http://www.zoho.com) all are free. Make sure you save your document in Microsoft Word format, or if you are working with data in Microsoft Excel. In addition the material needs to be placed in a format in which the client can utilize but also not alter the conclusions of the geospatial specialist. Therefore it is recommended that final reports be provided in a printable format such as Adobe Acrobat (pdf). There are free softwares that can be used to create pdf, CutePdf (http://www.cutepdf.com) is a good one. Assignments
10 Introduction to Geospatial Information Technology In this introductory module you will create several maps, reports and graphs to show basic functionality of the software. These items will allow you to learn how to use basic software function and also how to integrate content into maps. Specific operations will be part of the case studies.
You will submit several example maps to show that you understand the basic operations of the software prior to beginning the case studies. You will need to produce one brief report. In addition you will have a written assessment to prove basic knowledge. Module Requirements
As part of completion of this module will need to provide screen shots to your instructor, there several programs that can complete this operation for you. You can save your screen shot in any standard format, do not provide the mxd file, but save the file in case they are requested. You may wish to use Jing, which is a very good free screen capture program. http://www.jingproject.com. These exercises are not in a publication format they are only in a map creation format, to show experts. 1. Loading Data on Map - You will create a map of your state with county boundaries, major roads, rivers and major cities. Provide your instructor with screen captures of this successful operation. In this assignment you should have accomplished the skills of:
a. Unzip data set b. Load point, line and polygon data (all must be on same map)
c. Placing data in proper order Data Source: http://techcenter.jefferson.kctcs.edu/GIS/data/
Kentucky Data Source: http://techcenter.jefferson.kctcs.edu/GIS/data/country/USA/state/KY 2. Loading Raster Image - You will create a map of one or more raster images loaded onto the map. Provide your instructor with screen capture of this successful operation. The image should be in color and not black and white. The region should be a relative small region within your own state. Data Source: http://techcenter.jefferson.kctcs.edu/GIS/data/
Kentucky Data Sources: http://techcenter.jefferson.kctcs.edu/GIS/data/country/USA/state/KY/county/rowan/
http://techcenter.jefferson.kctcs.edu/GIS/data/country/USA/state/KY/county/henry/
http://techcenter.jefferson.kctcs.edu/GIS/data/country/USA/state/KY/county/Jefferson/
3. Report creation – You should create a short report, in which map images are loaded into the report, contain at least one tables and a spreadsheet graph. You should submit your report. Introduction to Geospatial Information Technology 11 The concept of the report should be to discuss the state in which you live and contain information about the state, the map should be a state map showing county boundaries, the graph should be a population growth over a defined period and the table should contain the numerical values. In this assignment you should learn: a. Import a map into word processor
b. Create a data chart c. Create a graph in a spreadsheet
d. Important graph into word processor e. Data Source: http://techcenter.jefferson.kctcs.edu/GIS/data/
4. Create a data file structure – You will create a data file structure on your computer and provide a screen capture of the structure, it is not expected that you will completely populate all states or counties. 5. Create a map that labels data – Create a county map of your state and make sure the counties are labeled in the state. You should provide your instructor a screen capture of the map. Note: Labeling is part of the layer property window.
Data Source: http://techcenter.jefferson.kctcs.edu/GIS/data/ Kentucky Data Source: http://techcenter.jefferson.kctcs.edu/GIS/data/country/USA/state/KY
6. There will also be a written assessment of the basic concepts that will show mastery of this chapter.
Case Studies Case Studies are being used for this course because they provide more real world scenarios and also allow the student to explore informational resources that maybe useful in working in the field of geospatial information technology. While each case is designed to learn specific techniques, they require multiple operations which is more realistic and also the creation of reports. Once the basic principles have been explored it is critically important that in-depth knowledge is obtained. This will be accomplished through six case studies, as part of these cases you will develop an expertise in the creation of maps and the reports to accompany them.
Each case will have technical skills that must be mastered to complete the case. Each skill is composed of an independent website that will provide, video, web and print material as well as the data to complete the skills. You will need to use multiple skills to complete each case, the combination of these multiple skills will give you the knowledge require to solve the problem. The same skill may be referenced in more
12 Introduction to Geospatial Information Technology than one module, since the cases can be done in any order. The order that the cases are listed is the suggested order of completion but you can choose to do the cases in a different order. In addition the each case will be provided information on how to locate the data as well as the locations of some of the data. There will also be a list of all modular prerequisites; this introductory module will serve as a prerequisite to all other modules. Each case will describe a real world scenario that must be solved. The scenarios will be explained both in a video format as well as a web and print medium. The case will also clear state the requirements that must be received by your instructor to successful complete the case. The report should be submitted as a single file or multiple files zipped together. The images should be contained within the report in general. Do not destroy you project files while they are not initially required they maybe needed by your instructor to understand how information was created.
Introduction to Geospatial Information Technology 13 Definitions:
The following definitions will be useful as you work in the geospatial fields. This list will be added to as needed so therefore it should not be considered a complete list but does have terms that are useful to you in this class. ArcCatalog – This is a program that is contained within ArcMap and is used to create new layers as well as manage shapefiles. This program can also be directly accessed without starting ArcMap. Bitmap – A bitmap is composed of discrete points that have a color. Bitmaps make up the dots on certain types of photographs and scans. Once a bitmap image reaches a display point that every dot or pixel is displayed than it will lose resolution. It also does not have the same sharpness if it is resized.
Blocks – See Census Blocks Buffering – Buffering is a process of placing concentric surfaces around a feature. For example if you want to determine all of the students that live 25 miles away from a school you would use a buffer around the point. You can also buffer around lines and polygons. You can have concentric buffers around shapefile elements, such as a 10-mile, 20-mile and 30-mile ring around a point. Buffered surfaces can also be combined together, such as two 20-mile rings that overlap can be made into a single surface.
Census Blocks – A Census block is the smallest unit in which data is divided into in the US Census data set. The name originally referred to city blocks, but now can be larger or smaller areas than a city block.
Census Tracts – A Census tract is contained within one county and is composed of multiple blocks. At the tract level the most data is available for demographical work.
Clipping – Clipping is the process of taking one layer (clipping layer) of information and using it as a surface to remove information that is outside of the boundaries of this layer. The layer should be a polygon. Coordinate Systems – A coordinate system is a grid system to identify every point on a map. The most common coordinate system is latitude/longitude system. The equator is a line of latitude; the other lines of latitude are measured north and south of the equator from 0 – 90 degrees. Lines of longitude are perpendicular to latitude and are measured east and west of the prime meridian from 0 – 180 degrees. There are other systems that measure locations in feet, meters and miles.
Demographics – Demographics is the study of selected population characteristics. For example the data that is obtained from the US Census Bureau in general is demographical information. Demographic characteristics might include gender, race, income levels, marital status, etc.
Digitization – Digitization is the process of taking analog information or imagery and converting it to a digital format. 1) You convert features on a photograph into a shapefile so that it can be displayed without the image. For example you digitize the location of a river from an aircraft photograph or you wish to digitize the major wooded areas in an image into polygon shapefiles. Once the information is in a 14 Introduction to Geospatial Information Technology shapefile format it can be used in numerous applications just as any other shapefile can be used. 2) You can also take a paper map and scan it. Then create a geocorrection to correspond the map to geographic coordinates.
GPS – Is a physical device that can detect signals from satellites. The satellite signals are timing information and by receiving data from multiple satellites the device can determine your position on the earth in three dimensions. The greater the number of satellites, the better the accuracy in determining your positions.
Geocoding – Geocoding is the process of placing geography with a street address. Geocoding will not work with post office boxes and rural routes.
Join – A join occurs when a data set is added to a shapefile, for example data from the US Census Bureau might be added to Census tracts.
Labels – A label is information that is placed onto a map about a specific data set. A layer might be the name of a county or road. When a layer appears on the map is an important criterion. For example in a state map you would not want the names of every city street to appear. Automatic label turning on and off is part of the labeling process.
Latitude – An earth coordinate that the equator is the zero line. The lines are parallel to the equator and measured north and south from the equator. Latitude lines are from 0 – 90 degrees north or 0 – 90 degrees south. Layer – A layer is a shapefile or image that has been placed onto a map. In general you place point files on top of line files, which are on top of polygons, raster images are usually placed at the lowest levels. If an opaque layer is placed above another layer the lower layer cannot be seen. You can also make opaque layers semi-transparent. Line – A line shapefile is an object that has length, but no width (the width can be changed in the representation but not in the geographical location). You can modify the displaying of a line file such as color, symbol and width. Roads and rivers are two common line files used in GIS. A river might be changed from line file to a polygon file at a specific zoom level. Longitude – An earth coordinate that goes from pole to pole and is perpendicular to the equator. Lines of longitude are measured from the prime meridian to the east and west. The values range from 0 – 180 degrees east and 0 – 180 degrees west.
Meridian – A meridian is the same as a line of longitude.
Merge – A merge is the process of combining more than one shapefile. The shapefiles to be combined should have the same attributes. Orthographic Projection – An orthographic projection represents a three-dimensional surface onto a two-dimension page. For example a photograph of the earth is a two-dimension image of a three- Introduction to Geospatial Information Technology 15 dimension surface, curvature errors become more of a problem as you move toward the edge of the image. Corrections to the image can be done so that curvature problems become a minimum. Point – A point shapefile is a single locate x,y item. The symbol, color and size of the icon representing the information can be changed, but the actual representation is a single location. Examples of point shapefiles might be a building, campus, residence or other information that at a specific scale is appropriate to represent as a single location. At different scales a polygon might be a better representation. For example a city might be represented as a point on world map but on a county map it might be a polygon. Polygon – A polygon shapefile is a closed figure that can be filled with a color. Zip code, county, state, census tracts and census blocks are all examples of polygons. Projections - A map projection represents the curved shape of the earth’s surface onto a flat surface. There are numerous types of projects that are used. Some projections work well in small region but errors increase as you move away from the targeted area.
Query – A query is when a logical question is asked of the data and then only specific data is shown on the map. For example, if you were looking at income levels, you might query the data to show those Census Tracts that have incomes less than $35,000 per year. Most major logic functions can be used and nested queries can be done with multiple data attributes.
Raster Image – A raster image a bitmap, which is usually either a photograph or a scan of an old map (such as a topographic sheet). Since it is a bitmap to maintain resolution there will be a maximum amount of zoom that can be used before it becomes distorted. Shapefile – A shapefile is a layer in a map. Theses files contain both a geography and data that can be projected onto a map. There are three types of shapefiles, point, line and polygon. Opaque layers should be displayed below transparent layers. In general point data is displayed above line data, which is displayed above polygon data. Raster Images are usually displayed as a bottom layer. Raster images are technically not a shapefile. Shapefiles are vector data.
State Plane – There are 126 geographic coordinate systems that designate areas of the United States. There may be one or more regions within a state; each state has at least one region. The state plan uses a simple x,y coordinate grid, while it works well within the region, errors become a major problem as you move outside the state plane area.
Symbology – Symbology deals with providing colors and line types to shapefiles as well as determining the type of data. In symbology you change the type of symbol, the color, the size and the break points of the data. You can also determine the number of breaks within the data and how the breaks are calculated as well as manually doing breaks within the data. Symbology is located in the properties window.
16 Introduction to Geospatial Information Technology Toolbox – Toolbox as its name indicates are group of geospatial tools that can be used within the ArcMap software. There are numerous different tools that will be discussed as need in different exercises. One tool of specific interest is the projection tool.
Tracts – see Census Tracts Vector – A vector is a mathematical tool, which displays the magnitude (length) and direction of a straight line. Vector data can be expanded and contracted without losing resolution. Shapefiles are vector data. For example a road shapefile would be composed of numerous vector segments, every time the road-changed direction a new segment would be created. If you zoom in on the road, it will be a sharp image because it contains all the information stored in a vector format. The length (magnitude) of the vector would be expanded proportionally to the zoom percentage and the angle would remain the same.
Introduction to Geospatial Information Technology 17