Introduction to the Geodatabase

What is a Geodatabase? What are feature classes and feature datasets? What are domains Design a personal Geodatabase Import data to a Geodatabase

What is a Geodatabase? A container for tables, feature classes, feature datasets…. Tables – attributes of rows and columns Standalone feature classes (conceptually like shape files) Feature datasets (a collection of feature classes) Rules and relationships A relational database that contain geographic information

Store geographic features represented as points, lines, or polygons, and their attributes; Can also store annotation and dimensions. Tables may contain additional attributes for a feature class Feature classes…..

Feature classes can be organized in Feature datasets. All feature classes in a feature dataset share the same coordinate system. Feature classes in a feature dataset can be organized into a geometric network. The network maintains topological relationships between its feature classes. Feature datasets…..

Personal geodatabase - stores data in a Microsoft Access database - size limit 2 GB - directly read through ArcCatalog - does not support raster data Multiuser geodatabases - data stored in IBM DB2, Informix, Oracle, or Microsoft SQL Server - connected through ArcSDE or direct - ArcSDE license necessary for editing - supports raster data Personal vs. Multiuser Geodatabase

All data (vector, raster, address, measures, CAD, etc.) is stored together in a commercial off-the- shelf DBMS Simplify support and maintenance, and reduce costs Allows multi-user access (with ArcSDE license) Support for intelligent features, rules, and relationships between feature classes Why Geodatabase?

Dynamic Geocoding Annotation subclasses Subtypes within Feature classes Coded attribute and range domains Improved topology and editing More advantages…..

…however they are simply modern equivalents of shapefiles and coverages stored in a commercial database. Confused? -The geodatabase may seem complicated…..

- Geodatabases can be created and managed easily using the standard tools in ArcCatalog - ArcMap and ArcToolbox provides tools to work with geodatabases Geodatabases in ArcGIS

Design process Create an empty Geodatabase in ArcCatalog Define the database structure Set spatial reference and coordinate domains Load data Define topology rules and relationships Creating a Geodatabase Think before you create

Design process What data layers to include in the geodatabase Shape files – Coverages Look-up tables How to organize the feature classes into logical feature datasets Think about what topolygy rules you may want to apply – how are the feature classes related to each other spatially?

Create a new Geodatabase in ArcCatalog

Shape files and coverages are converted to feature classes Attributes can be left out or renamed CAD data, dBase files, annotation etc. can be imported Data of the same spatial extent can be imported to the same feature dataset Migrating existing data into the Geodatabase

Importing existing data In ArcCatalog or ArcToolbox Tools and wizards are available Works with coverages, shapefiles, tables, CAD etc.

Creating Feature Datasets Right-click on the geodatabase – New – Feature Dataset Name the Feature Dataset and define the coordinate system Set X/Y domain Set Z domain and M domain Set manually or import from existing data sets

Coordinate Domains Lost data Large area Smaller precision (1,000) Small area larger precision (100,000) (0,0) Y X Max X and Y is 2.14 billion

Coordinate Domains The coordinate domain defines the area you can make edits in X and Y max is 2.14 billion for the database Default domain is 21000, Define your coordinate domains correctly the first time – they cannot be changed You can have a different coordinate domain for each feature class

What is max/min X and Y on the map? Max X and Y Min X and Y

Setting X/Y Domain Precision Min X ~ 2,145,320 Max X ~ 2,657,580 Min Y ~ 1,632,610 Max Y ~ 1,967,940 1 ft units, 1/1000 ft accuracy Precision = 1000/1 = 1000 (good enough) 1000

(0,0) Y X Max X and Y is 2.14 billion Most of the data is here in the database Large expansion options to the north and east Coordinate Domains

Coordinate Domains Calculations Min X ~ 2,145,320 Max X ~ 2,657,580 Min Y ~ 1,632,610 Max Y ~ 1,967,940 Precision 1000 These coordinates would put the data in the lower left corner – however we want to shift this to be able to expand in all directions (MinX + MaxX)/2 – (2.14 x 10 9 ) / (1000 x 2) = X min 2,401,450 – 1,070,000 = 1,331,450 (MinY + MaxY)/2 – (2.14 x 10 9 ) / (1000 x 2) = Y min 1,800,275 – 1,070,000 = 730,275

(MinX + MaxX)/2 + (2.14 x 10 9 ) / (1000 x 2) = X max 2,401, ,070,000 = 3,471,450 (MinY + MaxY)/2 + (2.14 x 10 9 ) / (1000 x 2) = Y max 1,800, ,070,000 = 2,870,275 Min X ~ 2,145,320 Max X ~ 2,657,580 Min Y ~ 1,632,610 Max Y ~ 1,967,940 Precision 1000 Min X = 1,331,450 Max X = 3,471,450 Min Y = 730,275 Max Y = 2,870,275 Precision 1000 Default x/y domain Shifted x/y domain Coordinate Domains Calculations

(0,0) Y X Max X and Y is 2.14 billion Most of the data is here in the database Large expansion options in all directions Coordinate Domains

The shifted x/y domain allows for editing within this window Max X, Max Y Min X, Min Y

Why create Feature Datsets? Data organization Topology rules Shared boundaries Geometric networks

Subtypes in feature classes Subtypes can only be created in ArcEditor and ArcInfo - A subtype is a group of objects that have similar properties within the Geodatabase For example the attribute ‘ZoneCode’ may have subtypes: - Commercial, Residential, Industrial Landcover vegetation types may have subtypes: - Forest, Agriculture, Rangeland, Urban

Attribute Domains Attribute domains are properties of the Geodatabase - Multiple objects may use the same domain - Can be created using the Domains properties dialog box Defines legal values for field attributes - Range domains (allowable numeric value range) - Coded value domain (in dropdown menus)

Questions?