Exercise 1-1
The tutorial showed how to diagram a geodatabase to include feature classes along with their associated tables, domains, and subtypes. The goal was to think through the design, adding data integrity and behavior guidelines to the database.
In this exercise, you will repeat the process for another dataset required by the city planner. This one will contain the zoning data for Oleander. The zoning code for a piece of property determines the type of development that is allowed on a parcel (even though the land use may be different). The zoning districts may incorporate several parcels and generally follow parcel boundaries, but they can split parcels, too.
The zoning districts will be represented by solid shaded polygons, so you will want to design a polygon feature class for districts. The edges of the polygons should be symbolized in one of two ways—either as a solid line representing a zoning boundary or a dashed line representing a change in allowable development density. Because of this scenario, you will want to design an additional linear feature class for symbology purposes. The codes necessary for the zoning information are as follows:
R-1Single Family Residential
R-1ASingle Family Attached
R-1LSingle Family Limited
R-2Duplex
R-3Triplex
R-4Quadruplex
R-5Multifamily
C-1Light Commercial
C-2Heavy Commercial
THTownhomes
LILimited Industrial
I-1Light Industrial
I-2Heavy Industrial
TX-121121 Development District
POSPublic Open Space
Analyze the descriptions of this data and determine what feature datasets and feature classes must be made, what fields they should contain, any domains that might need to be created (and possibly contingent domains), and any subtypes that might be beneficial.
•Print a set of the geodatabase design forms as necessary.
•Use the forms to create the logical model for feature classes for the zoning polygons and zoning boundaries.
•Investigate the use of domains and subtypes to build data integrity and behavior into your design.
WHAT TO TURN IN
If you are working in a classroom setting with an instructor, you may be required to submit the design forms you created in tutorial 1-1.
•The completed geodatabase worksheets for:
Review
Over the last 30 years, the way that geographic features have been portrayed, stored, and manipulated in geographic information systems (GIS) has evolved from a file-based technology into the present-day Esri geodatabase format. By using the Esri geodatabase, GIS practitioners can more realistically manage geographic features and their relationships to other features. Although computer technology has enhanced the behavioral aspects of these relationships, the fundamental ways that these geographic features are represented—by points, lines, and polygons—has largely remained unchanged. Esri geodatabase technology has improved the management of these points, lines, and polygons by providing tools to create geographic feature representations, enforce data integrity, and establish relationships among the geographic features that more closely model real-world situations.
As illustrated in the previous exercise, the opportunities to manage data using GIS methodology can be enhanced by careful thought and preplanning to ensure that an accurate portrayal of geographic features and their relationships is contained in the geodatabase. Preplanning the geodatabase is enhanced through a structured, organized logical data model to ensure that every conceivable relationship is accounted for in the model. This preplanning phase is no easy task. However, it is much easier to spend time at the outset designing your geodatabase than it is to change it once you’ve begun entering data into the model.
Organizing your geodatabase using feature classes and feature datasets allows you to refine relationships and behaviors for the data. Feature classes, as the most basic representation of geographic data in the geodatabase, can be logically grouped together to form feature datasets. Although there are many different techniques for organizing geographic data in the geodatabase, the organization of the data must be guided by the behavior of these features in the real world. For example, if feature classes contained in the geodatabase work together to form a geometric network, represent a terrain, or establish a topology, the feature classes must reside in the same feature dataset. Such behaviors among the data must be considered while designing the geodatabase.
Once your design is complete, using domains for your attribute data and other techniques will reduce costly mistakes during the data entry phase of your geodatabase’s development. Additional techniques provided by the geodatabase, such as the creation of subtypes, optimize how data is organized and utilized within the geodatabase. Using the many tools available within your project, and with a thoroughly planned approach, your new geodatabase will adequately portray the geographic features and associated relationships among them. As a result, your model of reality as contained in the geodatabase will represent the real-world features as closely as possible.
STUDY QUESTIONS
Answers to the study questions in this book are available on the instructor resources DVD.
1.What is a logical model of a geodatabase, and why should you develop a logical data model when designing your geodatabase?
2.What are the principal advantages of using subtypes? Give one example of a situation in which you would create a subtype, and specify why.
3.What are the principal advantages of using domains?
4.What is the difference between feature classes and feature datasets? When must you create a feature dataset?
Other study topics
Search for these key phrases in ArcGIS Pro Help for further reading:
1.Fundamentals of the geodatabase
2.What is a geodatabase?
3.Introduction to attribute domains
4.Fields, domains, and subtypes
Tutorial 1-2: Creating a geodatabase–expanding the logical model
The components of a geodatabase can have various spatial relationships, or behaviors, that form a topology. These behaviors can exist among points, lines, and polygons and will impact the logical model of a database. The most efficient designs will consider topology from the beginning.
LEARNING OBJECTIVES
•Design linear feature classes
•Investigate data behavior
•Design for topology
•Design point feature classes
Introduction
The first tutorial used the geodatabase design forms to construct a logical design for a parcels database. That dataset consisted of a polygon feature class along with a linear feature class to aid in symbolizing the parcel boundaries.