1. Data Structures & GeoDatabase

2. Introduction You have been using GDBs from nearly the start of the course Why? Because I think that most of the time you will be using GDBs! And…

3. Why? Because it is a convenient way to manage data –All types of data can be included –Features can be “smart” –Support of ArcGIS Data Models Because it provides an organizational structure that can represent real world features and behaviors (topology)

5. Know what? How to create a GDB How to create a FC How to create a FDS What you can put into a GDB What you can put into a FC What you can put into a FDS And How you add it to these parts of a GDB

6. Flavors of GeoDatabases File –Small groups, one edit, fast, smaller –Collection of files –Stores ~1 terabyte of data –File folder Personal –Small groups, one edit, Access DB, one file –Storage limited to ~2 gigabytes –Microsoft Access DB (so mdb is extension) ArcSDE –SDE = Spatial Database Engine –Enterprise version –Large groups working with data, including editing –Usually on a Server

7. The Geodatabase It is a single container for many feature classes (FC) (layers, {themes} of any one feature geometry and geography Quite often the FCs are stored in Feature Datasets (FDS) Data in a FDS can be topologically linked Topological links Annotation can be stored in the GDB Data files also Gray!

8. Feature Class (FC) Conceptual representation of a category of geographic features. Can include 1 or more point, line, & area features –but only one of these geometry types –And must be of the same spatial reference Data has to be Loaded or Imported

9. Feature Dataset (FDS) A collection of feature classes that share the same spatial reference. It is because they share the same spatial reference that they can participate in topological relationships with each other. Several feature classes may be stored in the same feature dataset. Many kinds of features and objects (tables) can be included

10. The GDB itself Has no spatial reference Is not fussy about what is put into it Features do not have to have the same spatial reference – but must have one!

11. The possibilities… From ESRI’s course Learning ArcGIS Desktop

12. Icons GDB Feature Dataset GDB table

13. Views of GDB Catalog View WE view

14. Views of GDB Catalog View WE view

15. Annotation

16. Vector data: Network

17. Topologies Many datasets have features that could share boundaries or corners By creating a Topology you set up rules defining how features share their geometries. Editing a boundary or vertex shared by two or more features updates the shape of all of them.

18. Topologies Many datasets have features that could share boundaries or corners By creating a Topology you set up rules defining how features share their geometries. Editing a boundary or vertex shared by two or more features updates the shape of all of them.

19. Geometric Networks Some vector datasets need to support connectivity tracing and network connectivity rules –Streams and rivers –Communications –Pipelines –Transportation (roads, railroads, canals) Geometric networks allow you to turn simple point and line features into network edge and junction features

20. Summary of data types NameRange, lengthApplications Short Integer -32,768 to 32,767 No fractions Long Integer -2,147,483,648 To 2,147,483,647 No fractions Float~-34E -38 to ~1.2E 38 Fractional values

21. Summary of data types NameRange, lengthApplications Double~ -2.2E -308 ~ 1.8E 308 Fractions OK Text <=64,000 char Names etc. Date mm/dd/yy hh:mm:ss Date and time

22. Precision and Scale When creating new fields an attribute table You will be asked for these Precision: Describes the number of digits that can be stored in the field. All digits are counted no matter what side of the decimal they are on. But not the decimal point.

23. Scale Scale:Sets the number of decimal places stored in a field. Used in Float and Double data field types. If the input table is a personal or file GeoDatabase the field scale will be ignored. The number 1234.567 would have a precision of 7 and a scale of 3. The business of precision and scale is actually much more complicated than this

24. Planning What is the problem? What data is needed (map scale, extent, etc.? What kinds of relationships are needed between FC? How will the data be organized (FDS)?