1. Copyright © 2005 Bruce Kessler All Rights Reserved Ch. 2 GeoDatabase Basics Laying the foundations

2. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-2 Goals History Benefits / disadvantages Feature geometry Types of GeoDatabases Managing a GeoDatabase –Structure –Spatial reference

3. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-3 GeoDatabase History/Description/Advantages Most of the structure was developed before ArcGIS Desktop software The framework for vector, raster, and tabular data storage in ArcGIS Unique data format Method for storing spatial and attribute data as well as other types of data (raster, tables, relationships, etc.) Has integrity rules Has operators Method for supporting transactional views: versions A means for modifying object behavior

4. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-4 Before Using A GeoDatabase Buy a full set of manuals!!!! Research your topics using White Papers Know how to and use the on-line help resources from ESRI – especially the Forums A

5. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-5 Benefits of a GeoDatabase Centralized management Large data management in a continuous integrated environment: raster/vector/tabular/CAD (SDE) Multi-user editing (SDE)

6. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-6 Benefits of a GeoDatabase Topology –Complex geometric networks –Geometric relationships within and between multiple feature classes Maintained through rules – simple polygon example

7. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-7 Benefits of a GeoDatabase Create and edit topologically integrated features with automatic maintenance Easily control exceptions to rule Support of advanced data types: measures, functional curves, Z values Feature-linked annotation

8. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-8 Benefits of a Geodatabase Efficient data entry with rules, relationships, and behavior Schema can be developed with CASE tools Custom objects

9. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-9 Review of Feature Geometry Point Multi-point Line –User-shaped –Curves –Single / multi-part Polygon –Single / multi-part

10. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-10 Review of Feature Coordinates X, Y – this is easy Z Elevation M Measure

11. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-11 Two types of GeoDatabases Personal –Access Multi-user –SDE

12. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-12 GeoDatabase (GDB) structure Stores –Feature datasets –Feature classes –Tables –Raster –More A unique structure within the GDB

13. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-13 GDB Objects: Feature Class (FC) A collection of features –Each feature class has one geometry type (point, multi-point, line, polygon) Can be stored in a feature dataset or ‘stand-alone’ Attributes are stored with coordinate data in one table

14. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-14 Spatial Reference Property of a feature class or feature dataset Components –Coordinate system –Coordinate domain Permanent after definition is saved –Warning: it may look like you changed the coordinate system, but you can’t and don’t try. It messes things up! See next slide for more information

15. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-15 Spatial Reference A

16. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-16 Coordinate domain Extent of available coordinates –Min and max X,Y coordinates –Precision = storage units per map unit Example, 1000 mm per meter Make sure it covers study area –Allow for growth ArcCatalog default –Import: data plus room for growth Set your own –Import from existing data –Type in extent for study area 2.14 billion storage units

17. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-17 Accuracy and Precision Accuracy in the Data –Scale of source map scale will determine accuracy* 1:600 (1”=50’)± 1.7 feet 1:1,200 (1”=100’)± 3.33 feet 1:2,400 (1”=200’)± 6.67 feet 1:4,800 (1”=400’)± 13.33 feet 1:24,000 ± 40.00 feet –Precision Ability to store the accuracy –Significant digits Single precision6-7 precise digits Double precision13-14 precise digits Geodatabase0-10 precise digits

18. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-18 Domain A property of a feature dataset or feature class (cannot change once set)

19. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-19 Standard Fields Feature classes have default fields –ObjectID – unique identifier –Shape – contains coordinates of feature –Area – automatically calculated and maintained for polygons Shape_Area (Personal GDB) –Length – automatically calculated and maintained for lines and polygons Shape_Length (Personal GDB)

20. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-20 GDB Objects: Feature Dataset A collection of feature classes –Environment for spatial reference –Environment for topology –Environment for coincident geometry and linked annotation –Feature classes inherit spatial reference Data loaded are projected on the fly, if necessary

21. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-21 Managing Your GDB ArcCatalog is your main tool to manage the schema –Construction of component parts –Organization of those parts –Properties for the parts Many capabilities are available –Some are not on the default GUI

22. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-22 Creating a GDB Personal –Use ArcCatalog Multi-user –Must be done at the system level A

23. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-23 Creating an empty feature class Two locations available: stand-alone and within a feature dataset A

24. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-24 Creating a feature dataset A

25. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-25 Tips Projecting data –Must create a new feature class PGDB is 2 GB max Read-only on a PGDB will restrict some analyses, such as Select by Location Use compact to clean up temporary files All table names need to be unique

26. Copyright © 2005 Bruce Kessler All Rights Reserved Skills for the GeoDatabase 2-26 Ex 2 Create a Personal GDB Create an empty Feature Class Create a Feature Dataset Create a Feature Class within the Feature Dataset