GeodatabasesPresentation By Farid UllahGIS AnalystForestry Planning & Monitoring CirclePeshawar

What Is A Geodatabase?Short for a geographic database.It is somewhat similar to the familiar file based coverage and shapefile data models but it is different in some important ways.It provides support for advanced geometry.It supports user-defined relationships among feature classes.It provides efficient storage of raster data.Allows multi user editing.

A Geodatabase its todays modern container for GIS data.

Geodatabase and Feature DatasetA geodatabase is a relational database that stores geographic information.A feature dataset is a collection of feature classes that share the same spatial reference frame.

Geodatabase modelStores geographic coordinates as one attribute (shape) in a relational database tableUses MS Access for Personal Geodatabase (single user)Uses Oracle, SQL/Server, dB2 or other commercial relational databases for Enterprise Geodatabases (many simultaneous users)Uses files in File GeodatabaseShape

ArcGIS Geodatabase

What Are Some Advantages Of A Geodatabase?Large Geodatabase feature classes can be stored seamlessly, not tiled.In addition to generic features, such as points, lines, and polygons, you can create custom features, such as transformers, pipes, and parcels. These custom features can have special behavior to better represent real-world objects. You can use this behavior to support sophisticated modeling of networks, data entry error prevention, custom rendering of features, and custom forms for inspecting or entering attributes of features. Supports topology. Topology in a Geodatabase allows you to represent shared geometry between features within a feature class and between different feature classes. Supports multi-user editing.

There are Two Types of GeodatabasesPersonal GeodatabasesAvailable to all ArcGIS users.Similar to file based workspaces, can support up to 2GB of data.Stores data in an MS Access Database.Do not support multi-user editing.Great for smaller projects

Multi-user GeodatabasesRequire the use of ArcSDE.Compatible with several DBMS (DB2, Informix, MS SQL Server, Oracle Spatial or Locator)Primarily used in enterprise settings.Supports many simultaneous users.For large continuous databases.Supports Versioned workflows.

What Can I do with my License Level?

Create a GeodatabaseThe first step is to create the database in ArcCatalog.In ArcCatalog Right-click the location in the ArcCatalog tree where you want to create the new Geodatabase.Select NewSelect Personal Geodatabase.Enter a name for the Geodatabase.

Create a Feature DatasetRight click your Geodatabase.Select New.Select Feature Dataset.Add a name.Select the Edit button to edit the spatial reference.The Spatial Reference Properties dialog box appears.

Set the Spatial ReferenceYou can import the spatial reference from an existing shapefile or feature class or feature dataset.You can also select a spatial reference from file.Navigate to the spatial reference you want to use or navigate to the feature class or feature dataset whose spatial reference you want to use as a template.

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Set the X/Y Domain of the Feature ClassIf you imported your spatial reference this will already be done, if not.Select the X/Y Domain tab.You need to define the spatial envelope that the data will exist within.Best way to do this is with ArcMap by drawing a rectangle around a dataset that is in your chosen coordinate system. Make sure you choose an extent bigger then the area you really need.Right click on the graphic.Select Properties.Select the Size and Position tab.

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Get the X/Y LocationsClick on the box in the upper right corner.Copy the numbers for the X and Y position to your notepad.Do the same for the lower left hand side of the graphic.Then past your data in the appropriate fields in the Spatial Reference Properties Dialog.The rest of the fields can use the default setting.Ok to exit.The Feature Dataset is now created. It is also empty.

Load data into your Feature DatasetYou can load data from existing shapefiles or feature datasets.You can also create empty feature classes.To load a dataset, right click the feature class and choose Import, then choose Feature Class (Single).Navigate to the feature class that you want to import.Name the dataset and press ok.

Create a New Feature ClassRight click the Feature Dataset.Choose New, then Feature Class.The Feature class dialog box appears. Enter a name.Click Next, Choose Default.Add any additional fields you would like.Select the field type.Press ok.Your empty feature class now appears.

The Importance of your X/Y Domain Adding data inside the rectangular extent of your X/Y Domain.Adding data outside the rectangular extent of your X/Y Domain.The second one doesn't work.You should always set your domain larger then what you need.

TopologyNeed an Editor or Info license.Managed as a set of validation rules that define how features may share a graphic space.RulesRanksCluster ToleranceHelps to ensure the spatial integrity of data.Streets may be modeled so they never share line segments and they snap at intersections.Parcels may be modeled so they dont overlap or have gaps.

Topology RulesPolygon RulesMust Not OverlapMust Not Have GapsMust Not Overlap WithMust Be Covered By Feature Class OfMust Cover Each OtherBoundary Must Be Covered ByArea Boundary Must Be Covered By Boundary OfContains Point

Line RulesMust Not OverlapMust Not IntersectMust Not Have DanglesMust Not Have PseudosMust Not Intersect Or Touch Interior

Must Not Overlap WithMust Be Covered By Feature Class OfMust Be Covered By Boundary OfEndpoint Must Be Covered ByMust Not Self OverlapMust Be Single Part

Point RulesMust Be Covered By Boundary OfMust Be Properly Inside PolygonsMust Be Covered By Endpoint OfMust Be Covered By Line

RanksRanks control how features are snapped together.Lower ranking features snap to higher ranking features.Equally ranked features snap to the geometric average of the two features.

Cluster ToleranceThe cluster tolerance is the distance at which two features are considered coincident.When you validate a topology, features within the cluster tolerance are snapped together.

Create a TopologyAll of the layers that will be part of the topology have to be in the same feature dataset.Right-click the feature dataset and choose New, then topology.Click Next in the Topology Wizard.Enter the topology name.Enter the cluster tolerance.Select the layers that will participate in the topology.Set the rank. Click Add Rule.Select the rules you would like to add.Click OK and Finish.Click yes to finish Topology, click yes to validate.

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Results of the Topology

Multi-User DatabaseVersion AVersion BVersion C

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