introduction to arcgis i (for arcview 8, arceditor 8, and...

IntroductionIntroduction to ArcGIS I (for ArcView 8, ArcEditor 8, and ArcInfo 8) 1-1


Course objectivesThis course will introduce you to ArcGIS and provide the foundation for you to become a successful ArcView, ArcEditor, or ArcInfo user. You will learn how to use ArcMap, ArcCatalog, and ArcToolbox and explore how these applications work together to provide a complete GIS software solution. The course covers fundamental GIS concepts as well as how to create, edit, and work with georeferenced spatial data. You will learn how to manipulate tabular data, query a GIS database, and present data clearly and efficiently using maps and charts.

This course covers a variety of topics but may not include specific tools or concepts used in your applications. If you have questions about particular functionality that does not appear to be covered by this class, feel free to ask your instructor.


ArcGIS is the name used to identify ESRI’s flagship family of GIS products. ArcGIS includes client software, server software, and data components. ArcGIS itself is not a GIS application; rather, it is a system of software products, each servicing a specific need.

Software products and applications

When someone purchases an ArcGIS system, they license software products which include one or more software applications. Understanding the difference between products and applications is important in understanding how ArcGIS is structured, and how the topics covered in this training class relate to the system as a whole.

For example, one group may license the ArcView software product, which includes the ArcMap, ArcCatalog, and ArcToolbox applications. Another group may license the ArcEditor software product, which includes the same three applications. After installing their respective products, both groups would find icons for the ArcMap, ArcCatalog, and ArcToolbox applications in their Start menus; neither would find an ArcView or ArcEditor icon. But upon running the applications, the ArcEditor group would find more useful buttons and menu choices than the ArcView group.

In another example, a group who licenses the ArcSDE software product may install and use the ArcSDE, ArcSDE CAD Client, and ArcSDE for Coverages applications.


Support resources

ESRI’s primary resource for software support is the Online Support Center (OSC) at http://support.esri.com. From the OSC you can request assistance from ESRI Technical Support, interact with other ESRI software users, and even help yourself to technical information and downloads.

Support resources are grouped by software product. When you click the name of a software product, a list of available resources expands below the name. In the graphic above, clicking the ArcGIS Desktop product name reveals links to technical articles, downloads, system requirements, and more.

Downloads

Software upgrades—also called service packs, patches, updates, and utilities—are ESRI-provided enhancements. These upgrades range from handy tools that facilitate common tasks to system upgrades that resolve bugs, improve performance, and add support for additional platforms. Unless otherwise stated in their descriptions, software upgrades are fully supported by ESRI Technical Support.

In-depth technical papers discuss topics like system design, performance, and integration. Documents available through the Technical papers link are written by ESRI, and the recommendations they make are fully supported by ESRI Technical Support.

The ArcScripts site is a repository of software utilities (scripts) supplied by the ESRI user community for the benefit of its peers. Here you will find ArcScripts, as these utilities are called, for most ESRI software products and customization environments, including ArcGIS VBA, Avenue, and AML. Download scripts anonymously, and create a free account to post tools to the archive. ArcScripts are provided as-is and are not supported by ESRI Technical Support. You may, however, purchase technical support for a per-incident fee.


Definitions of a geographic information system can vary considerably. The definition provided here combines both the components and functions of a GIS. The components needed to perform GIS tasks include:

People

This is the most important component in a GIS. People must develop the procedures and define the tasks of the GIS. People can often overcome shortcomings in other components of the GIS, but the best software and computers in the world cannot compensate for the incompetence of people.

Data

The availability and accuracy of data can affect the results of any query or analysis.

Hardware

Hardware capabilities affect processing speed, ease of use, and the type of output available.

Software

This includes not only actual GIS software, but also various database, drawing, statistical, imaging, or other software.

Procedures

Analysis requires well-defined, consistent methods to produce accurate, reproducible results.


Any GIS should be capable of the following fundamental operations in order to be useful for finding solutions to real-world problems.

Capturing data

A GIS must provide methods for inputting geographic (coordinate) and tabular (attribute) data. The more input methods available, the more versatile the GIS.

Storing data

There are two basic data models for geographic data storage: vector and raster. A GIS should be able to store geographic data in both models.

Querying data

A GIS must provide utilities for finding specific features based on location or attribute value.

Analyzing data

A GIS must be able to answer questions regarding the interaction of spatial relationships between multiple datasets.

Displaying data

A GIS must have tools for visualizing geographic features using a variety of symbology.

Output

A GIS must be able to display results in a variety of formats, such as maps, reports, and

Introduction

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Introduction to ArcGIS I (for ArcView 8, ArcEditor 8, and ArcInfo 8) 1-8


Because the geographic database is the expensive and long-lived component of the GIS, data entry is an important consideration. ArcGIS integrates a variety of data types from a variety of sources, so it provides multiple data entry options. ArcGIS offers efficient data entry methods for automating paper maps and other nondigital data sources. To take advantage of the vast collection of geographically referenced data that already exists in digital format, ArcGIS provides the most comprehensive data conversion capability of any GIS on the market. ArcGIS software's integrative capabilities also allow data to be shared with other applications without the need for conversion.


You can represent geographic features in vector or raster format.

Vector data

The vector data model represents geographic features much the same way maps do—using points, lines, and areas. An x,y (Cartesian) coordinate system references real-world locations.

Raster data

Instead of representing features by their x,y coordinates, the raster data model assigns values to cells that cover coordinate locations. Raster format is well suited to spatial analysis and is also appropriate for storing data collected in grid format. The amount of detail you can show for a particular feature depends on the size of the cells in the grid. This makes raster data inappropriate for applications where discrete boundaries must be known, such as parcel management.


Identifying specific features

One common type of GIS query is to determine what exists at a particular location. In this type of query, the user understands where the features of interest are, but wants to know whatcharacteristics are associated with them. This can be accomplished with GIS because the spatial features are linked to the descriptive characteristics.

Identifying features based on conditions

Another type of GIS query is to determine the locations that satisfy certain conditions. In this case the user knows what characteristics are important and wants to find out where the features are that have those characteristics.


You can perform analysis to obtain the answers to a particular question or find solutions to a particular problem. Geographic analysis usually involves more than one geographic dataset and requires the analyst to proceed through a series of steps to reach a result. Three common types of geographic analysis are:

Proximity analysis

• How many houses lie within 100 meters of this water main?

• What is the total number of customers within 10 kilometers of this store?

• What proportion of the alfalfa crop is within 500 meters of the well?

To answer such questions, GIS technology uses a process called buffering to determine the proximity between features.

Overlay analysis

An overlay process combines the features of two layers to create a new layer that contains the attributes of both. This resulting layer can be analyzed to determine which features overlap, or to find out how much of a feature is in one or more areas. An overlay could be done to combine soil and vegetation layers to calculate the area of a certain vegetation type on a specific type of soil.

Network analysis

This type of analysis examines how linear features are connected and how easily resources can flow through them.


For many types of geographic operations, the end result is usually best visualized as a map or graph. Maps are efficient for storing and communicating geographic information. Cartographers have created maps for millennia, but GIS provides new and exciting tools to extend the art and science of cartography. Maps can be integrated with reports, three-dimensional (3D) views, photographic images, and other digital media. This topic is discussed in greater detail in Lesson 3.


Sharing the results of your geographic labor is one of the primary justifications for investing resources in GIS. Taking displays created through a GIS and outputting them into a distributable format is a great way to do this. The more avenues for output a GIS can offer, the greater the potential for reaching the right audience with the right information.


Organizing spatial data

A GIS organizes and stores information about the world as a collection of thematic layers that can be linked by geography. Each layer contains features with similar attributes, like streets and cities, that are located in the same geographic extent. This simple but powerful and versatile concept has proven invaluable for solving real-world problems from tracking delivery vehicles to modeling global atmospheric circulation.

The onion analogy

Think of the world as a large onion. When you peel an onion, you see that it is composed of many layers. Real-world entities can be seen the same way; the earth can be “peeled” into many layers, each representing a different theme. For example, you can put all the streets in one layer and all the landuse areas in another layer. As you can imagine, the earth’s complexity allows you to create as many layers as you want. The question then becomes how to best organize these real-world entities into manageable geometric shapes (point, line, area) and store them digitally.


Abstracting real-world entities

It is impossible to capture everything from reality inside a computer. Instead, GIS users must somehow abstract real-world phenomena, or entities, into a geometric representation of those entities. There are three basic geometric shapes used for geographic features: points, lines, and areas. These shapes can be called geometric objects, geometric features, or feature types.

Note that there are different methods of making these entities digital, including scanning and digitizing.


Map scale is an important, but often misunderstood, concept in cartography. To represent a portion of the earth’s surface on a map, the area must be reduced. The extent of this reduction is expressed as a ratio called map scale. Map scale is the ratio of map distance to ground distance.

For example, if we draw a 4.8-km road as a 20-cm line on our map, the following statements would describe the map scale:

20 cm : 4.8 km, 20 cm : 480,000 cm, 1 cm : 24,000 cm, 1 : 24,000

The latter is known as a representative fraction (RF) because the values on either side of the colon represent the proportion between distance on the map and distance on the ground; that is, “1:24,000” means “1 map inch represents 24,000 ground inches”, “1 map meter represents 24,000 ground meters”, or “1 map centimeter represents 24,000 ground centimeters”, and so on.

Map scale can be expressed in several different manners: as a fraction (1:24,000), as a verbal statement (one centimeter equals one kilometer), or as a bar.

Map scale indicates how much a given distance was reduced to be represented on a map. For maps with the same paper size, features on a small-scale map (1:1,000,000) will look smaller than those of a large-scale map (1:1,200). In other words, a dime-sized lake on a large scale map (l:1,200) would be less than the size of the period at the end of this sentence on a small-scale map (1:1,000,000).

In general, small-scale maps depict large ground areas, but they have low spatial resolution, showing little detail. On the other hand, large-scale maps depict small ground areas, but have high spatial resolution, showing many details. The features on large-scale maps more closely represent real-world features because the extent of reduction is lower than that of a small-scale map. As map scale decreases, features must be smoothed and simplified or not shown at all. For example, at a scale of 1:63,360 (in which 1 inch = 1 mile), it is difficult to represent area features smaller than 1/8th of a mile long or wide because they will be 1/8th of an inch long or wide on a map.


Geometry

Geometry represents the geographic features associated with real-world locations. Geographic features are abstracted into points, lines, or areas.

Attributes

Attributes provide descriptive characteristics of the geographic features.Behavior

Behavior means geographic features can be made to follow certain types of editing, display, or analysis rules, depending on circumstances defined by the user.


The relationships between features on a map, or where they are located in space relative to one another, communicates important information. Connectivity, adjacency, and containment are types of spatial relationships shown in the graphic above. Interstate 80 connects San Francisco with New York City. San Francisco is adjacent to the Pacific Ocean, and California is withinthe USA.

The spatial relationships between connecting or adjacent features in a geographic data layer are often referred to as topologic relationships. Topology is the branch of geometry that deals with the properties of features that remain unchanged even when the features are bent, stretched, or otherwise distorted.

ArcGIS uses these spatial relationships and feature properties like area, length, and direction to identify complex spatial patterns.


The ArcGIS Desktop includes a suite of integrated applications: ArcMap, ArcCatalog, and ArcToolbox and Geoprocessor interfaces. Using these applications together, you can perform any GIS task, simple to advanced, including mapping, data management, geographic analysis, data editing, and geoprocessing. In addition, ArcGIS allows you to tap in to an abundance of spatial data and resources available through ArcIMS services on the Internet or stored in an ArcSDE® database. The ArcGIS Desktop is a comprehensive, integrated, scalable system designed to meet the needs of a wide range of GIS users.

The ArcGIS Desktop can be accessed using three software products, each providing a higher level of functionality. ArcView provides comprehensive mapping and analysis tools along with simple editing and geoprocessing tools. ArcEditor includes the full functionality of ArcView, plus advanced editing capabilities. ArcInfo extends the functionality of both to include advanced geoprocessing and also includes the applications for ArcInfo Workstation (Arc, ARCPLOT™, ARCEDIT™, and so on).

Because the ArcGIS products all share a common architecture, users working with any of these clients can share their work with other users. Maps, data, symbology, map layers, custom tools and interfaces, reports, metadata, and so on, can be accessed interchangeably in all three products.

Much more information about the entire ESRI product line can be found at http://www.esri.com.


All ArcGIS products (ArcView, ArcEditor, and ArcInfo) are comprised of the ArcMap and ArcCatalog applications, both of which contain the Toolbox and Geoprocessing windows. ArcMap is the application for performing analysis and making maps. ArcCatalog is a tool for accessing and managing your data. ArcToolbox contains tools for data conversion and management. The Geoprocessing window allows you to write, import and run scripts, and access individual commands.


ArcMap provides tools for creating visual displays of your data, querying, and creating presentation-quality maps. ArcMap makes it easy to lay out your maps for printing, embedding in other documents, or electronic publishing. It also includes analysis, charting, reporting functions, and a comprehensive suite of editing tools for creating and editing geographic data. When you save a map, all of your layout work, symbols, text, and graphics are automatically preserved.

ArcMap is the primary ArcGIS application for displaying, querying, editing, creating, and analyzing data.


The ArcCatalog application helps you organize and manage all your GIS data. It includes tools for browsing and finding geographic information, recording and viewing metadata, quickly viewing any dataset, and defining the schema structure for your geographic data layers.


The ArcToolbox window provides you with tools for data conversion, managing coordinate systems, changing map projections, and more. ArcToolbox supports easy-to-use drag-and-drop operations from ArcCatalog; with ArcMap, you need to browse to or type in the variables. For ArcInfo users, ArcToolbox provides additional and more sophisticated data conversion and spatial analysis tools.


The ArcGIS Desktop Help provides several methods for finding the help you need to use the software most productively. The Contents tab lets you search for information by topic. The Index tab lets you search for topics containing words from the Help index, such as Layer or Table. The Search tab lets you search the Help document for a word you specify. The Favorites tab lets you store your favorite help topics so you can easily access them when needed. Your word does not have to be in the index in order to search the document for it, but the search will take longer if it is not in the index.

In ArcCatalog, ArcMap, and ArcToolbox, button and tool names are displayed when you move the mouse over them (these are called ToolTips). You can also click the What’s This? tool in ArcMap or ArcCatalog and then click on a button or tool to access additional help about it (this is called context-sensitive help). For applications like ArcMap that have graphical user interfaces, context-sensitive help is useful for finding out what all the various buttons and tools do.

Selecting the ESRI Support Center link will connect you with a wealth of additional online resources. The Web site URL is http://support.esri.com.


At this point, your instructor may choose to demonstrate some of the concepts discussed in this lesson. You will also be introduced to the ArcGIS applications you will use for the remainder of the class.