"Coincidentally" the Geodatabase, Part 1

"Coincidentally"

Over the years, I've noticed that many people have yet to explore the power of an ArcGIS geodatabase. What I mean is that some users are still strong-arming their way with shapefiles (sigh) because they are comfortable with them or are simply loading their data into a geodatabase as a feature class. COME ON! Geodatabases have been around since about 2001. It's time to capitalize on that powerful tool you have with ArcGIS.

The plan

This series of blogs is going to focus on feature coincidence. To get there will take a number of weeks of blogs to fully post this series. Here's my plan:

Part 1 -- introduce the feature dataset and how to add your shapefiles

Part 2 -- introduce topology and two very useful rules: Must Not Overlap and Must Not Have Gaps

Part 3 -- introduce working with coincidence and Area Boundary Must Be Covered By Boundary Of

Part 4 -- editing Area Boundary Must Be Covered By Boundary Of errors

This information is taken in part from my ArcGIS Desktop: Geodatabase Power User class. For more in-depth detail, you can sign up for my class. More information at Web Classes.

Required software: 

Standard or Advanced version of ArcGIS Desktop (it used to be called ArcEditor and ArcInfo) version 10.1. (Much of this can be done with older versions of the software. I cannot keep track of what all works and doesn't work with the older versions.)  Since we will be building geodatabases in this series, Basic ArcGIS (ArcView) users don't have all the capabilities.

Assumptions:

I assume you know what a feature class is. Also, how to make a geodatabase and some of the basic functionality of one. If not, the ArcGIS Desktop: Managing Data class is a great way to get all the foundations about geodatabases and editing and managing feature data. Again, more information about my classes can be found at Web Classes.

The Feature Dataset (FD):

This geodatabase contains four feature datasets.

• Is a collection of feature classes (GirdD FD contains two)
• Is the environment for spatial reference
• Is the environment for topology (GirdD FD contains one)
• Is the environment for coincident geometry (topologic rules)
• Feature classes stored within an FD inherit it's spatial reference properties
• Feature data loaded into an FD can be projected on the fly

The FD provides the user with the “framework” to organize logical collections of feature classes (even different feature types – point, line, poly) together to represent the behavior and topologic relationships that the individual feature classes share. The extent of the flexibility delivered in using FD's is very exhaustive and efficient, but it does take some practice to capitalize on these capabilities. FD's contain “user grouped” feature classes. This allows the user to more accurately and efficiently model real world entities as “feature groupings” and establish topological relationships between those feature classes that participate in the topology. All of this is accomplished as a structured collection of tables in the RDBMS, thus exploiting the performance benefits of the database.

The FD can be interpreted as the “container” for feature classes. Benefit can be reaped from having a spatial reference defined for the FD so when new feature classes are loaded into an existing FD, the data will “project on the fly” (if necessary) into the spatial reference of the FD.

Creating a Feature Dataset:

Creating a feature dataset is quite easy. Using ArcCatalog or the Catalog Window in ArcMap, simply right-click on your geodatabase and choose New > Feature Dataset... 

There are some properties you will need to set when creating one: name, coordinate systems, and tolerance. I'm assuming you know how to work with feature classes, so I won't go through coordinate systems or tolerance as these are basic pieces of knowledge for feature classes. If you are unsure of these properties, now is the time to make certain you know exactly what is going on. These properties will affect the outcome of all feature classes within your FD.

Importing and Projecting Feature Data:

You now have a template (your FD) for importing shapefile or other feature data. Right-click on the FD and choose Import > Feature Class (single)... or Import > Feature Class (multiple)...

Simply use the tool to browse to and choose your shapefile. By the way, it is VERY easy to import 10, 20 or 100 shapefiles this way. 

You may choose a shapefile that is in the same coordinate system as your FD. It imports easily and quickly. You may also choose a shapefile that is NOT in the same coordinate system as your FD. In this case, it will project 'on the fly' as long as your input shapefile's coordinate system is correctly defined. If you are working with different datum's  I suggest projecting/transforming your shapefile before importing so you can easily keep track of all the properties. 

Here's the Feature Class to Feature Class tool populated with my example shapefile. 

The result:

So there you have it! A shapefile loaded into a feature dataset. 

In Part 2, I'll introduce topology and two very useful rules: Must Not Overlap and Must Not Have Gaps. I'll actually be using two real-world examples of parcels and zoning. 

As always, I appreciate your comments, suggestions, and even spelling correcetions!

Until then... Happy Geodatabasing!