1 / 56

The Geodatabase

Explore the basics of geodatabases in GIS, including data formats, structures, and the difference between personal and enterprise geodatabases. Learn about the components and building of geodatabases.

delorisw
Download Presentation

The Geodatabase

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Geodatabase GISC 6382 Applied GIS UT-Dallas Briggs

  2. Geodatabase Fundamentals • Spatial data formats • Geodatabase data structure • Personal vs. enterprise geodatabase • Components of geodatabase • Building geodatabase GISC 6382 Applied GIS UT-Dallas Briggs

  3. Geographic Feature Data Formats • Formats are based on representations (models) of the real world that can be placed in a GIS to produce maps, perform interactive queries, and execute analyses. • CAD – first computer mapping model/format. • Binary file format with little attribute information. • Coverage – native ArcInfo 7 format. • Based on Georelational data model. • Vector data is maintained in indexed binary files and partitioned from, but linked to attribute tables by a common identifier. • Topological relationships are maintained. • Shortcomings – features aggregated into collections of points, lines & polygons with generic behavior. The behavior of a line representing a road is the same as the behavior of a line representing a stream. GISC 6382 Applied GIS UT-Dallas Briggs

  4. Geographic Feature Data Formats • Shapefile – introduced with ArcView • Also georelational data model – nontopological vector data format. • Very prolific format – much GIS data in Shapefile format. • Simpler than coverage because they do not store topological associations among different features and feature classes. • Limited analysis capabilities due to lack of topology • Geodatabase – introduced in ArcInfo 8. • Object-oriented model – can characterize features more naturally by defining object types, topological, spatial and general relationships, and interactions. • Geodatabase features can be stored in a single database. • Create custom features in addition to points, lines, polygons • Brings physical model closer to logical model. GISC 6382 Applied GIS UT-Dallas Briggs

  5. What is a Geodatabase? • A new type of geographic data format (GDF) • Based on Object-Oriented Model • Users can add behavior, properties, rules and relationships to data • Implemented as extension to standard relational database technology • Supports topologically integrated feature classes • Extends the coverage model with support for complex networks, relationships among feature classes, and other object-oriented features • Provides platform for development of custom data models using visual tools like CASE (Computer Aided Software Engineering) tools and UML (Unified Modeling Language) notation GISC 6382 Applied GIS UT-Dallas Briggs

  6. ArcCatalog Is the Principal User Interface Used to Define and Manage the Geodatabase GISC 6382 Applied GIS UT-Dallas Briggs

  7. ArcCatalog ArcMap Geodatabase Framework GISC 6382 Applied GIS UT-Dallas Briggs

  8. Personal (single-user) Geodatabase • Personal Geodatabase. • Implemented as a Microsoft Access database (*.mdb file) by using MS jet engine which is installed with AI8. MS access is not needed. • Can be placed on local or network drives. • Generally used for personal or small work-group use. • Can handle small to moderately sized datasets. • Full functionality of geodatabase served through ArcSDE except versioning. • Versioning – allows many editors to work concurrently and includes framework to resolve edit conflicts. • If a personal geodatabase is deleted its gone. GISC 6382 Applied GIS UT-Dallas Briggs

  9. Enterprise (Multi-user) Geodatabase • ArcSDE Geodatabase • ArcSDE is the multi-user data access extension to ArcInfo (bundled w/software) that serves geodatabases to AI applications running on pc’s on TCP/IP network. • Used for demanding datasets requiring concurrent editing by multiple users. • Created by installing a DBMS and ArcSDE on a server. • ArcCatalog only creates and deletes connections to ArcSDE geodatabases. • Can be deployed on UNIX or Windows NT. • Many use UNIX platform for ArcSDE and DBMS and NT for AI applications • ArcSDE is centrally tuned and managed by a DBA. • Can build SQL applications to access tables in a remote geodatabase. GISC 6382 Applied GIS UT-Dallas Briggs

  10. Geodatabase Elements • Objects & Object classes • Features & Feature classes • Feature datasets • Spatial references • Domains • Subtypes • Relationships & Relationship classes • Geometric networks • Labels and Annotation GISC 6382 Applied GIS UT-Dallas Briggs

  11. Objects & Object Classes • Geodatabases organize geographic data into a hierarchy of data objects. • Objects are instances of an object class that have properties and behavior. • Objects can be related to other objects via relationships • Objects have unique system identifiers (OID) • Object classes are tables in a geodatabase storing non-spatial data (e.g., Parcel owners) • Objects in an object class have the same • Properties - stored in the table as attributes • Behavior - implemented as a component GISC 6382 Applied GIS UT-Dallas Briggs

  12. Object Classes (tables) A row stores an Object GISC 6382 Applied GIS UT-Dallas Briggs

  13. Features and Feature Classes • Features are objects with required shape (Points, Multi-points, Lines & Polygons) that represent a real world object in a layer on a map. • Features classes are collections of features with same type of feature geometry and attributes. • A feature class is also an object class which stores spatial objects (features) (e.g., Parcels). • All the features in a feature class are in the same spatial reference. • Feature classes which store topological features must be contained within a feature dataset to ensure a common spatial reference. GISC 6382 Applied GIS UT-Dallas Briggs

  14. Feature Classes Feature Class Table A row stores feature BLOB: Binary Large Object Block GISC 6382 Applied GIS UT-Dallas Briggs

  15. Feature Datasets • Containers for feature classes • Shared spatial reference • Analogous to a coverage • less restrictive • May also contain • relationship classes • geometric networks • Annotations GISC 6382 Applied GIS UT-Dallas Briggs

  16. Building a Geodatabase Design geodatabase • Building a geodatabase • Designing the geodatabase • (Think before you create) • Creating a new geodatabase • (Name and location only) • Defining the geodatabase structure • (Schema and data) • Entering spatial data • (Loading or automation) • Define additional properties • (Validataion, relationships, networks) Create a new geodatabase Defining GDB structure Geodatabase Entering spatial data Define additional properties GISC 6382 Applied GIS UT-Dallas Briggs

  17. Designing a Geodatabase • Conceptual Plan: Current and future needs • Data contents • Coordinate system • Data validation and modification rules • Relationships among objects • Custom objects • Logical Design • Can use CASE tools • What needs to store (Not how to store) • UML Use Case • Microsoft Visio Enterprise Edition Microsoft Visio Enterprise Version GISC 6382 Applied GIS UT-Dallas Briggs

  18. Creating a New Geodatabase • Create a new geodatabase using ArcCatalog • Create new • Rename default name GISC 6382 Applied GIS UT-Dallas Briggs

  19. Defining Geodatabase Structure • Create from scratch manually. • Use tools in ArcCatalog to create schema • Importing existing database schema • Can convert by importing schema from existing datasets • Use CASE tools and UML to automate database creation. • Can use CASE tools to create new custom objects and/or generate a geodatabase schema from UML • CASE (Computer Aided Software Engineering) • UML (Unified Modeling Language) GISC 6382 Applied GIS UT-Dallas Briggs

  20. Create schema from scratch manually • Define structure using ArcCatalog • Feature datasets • Feature classes • Tables • Relationship classes • What to Define? • Database name • Field name and properties • Spatial reference • Table relationship parameters GISC 6382 Applied GIS UT-Dallas Briggs

  21. Importing existing database schema • Import data and/or database schema • Shape files, coverage, features class • INFO, dBase tables • Options while importing • Rename object • Rename or exclude attribute columns • Modify spatial reference • Insert feature class into feature dataset GISC 6382 Applied GIS UT-Dallas Briggs

  22. Use CASE tools and UML to define database structure • Physical Design using UML • Feature class, relationship class, subtype and/or domain schema • Design large database with visualization and documentation of data relationship and attributes • Edit ESRI Object Model diagram • Create customize objects inherited from ESRI objects (ArcObjects) • Export structure to Microsoft Repository, then to ArcCatalog • Visual Basic with GIS Applications (Visual Basic + MapObjects), Substitute Computer Techniques • GIS Application Software Development (ArcObjects + UML) GISC 6382 Applied GIS UT-Dallas Briggs

  23. Entering Spatial Data • Spatial data automation options • Analog data: digitizing or scanning • Arc/Info formats: importing and loading • Other digital data: data conversion • Data Mapping • Vector geometry types (p. 81) • X, Y: Points, multipoints, lines, polygons • Z: Optional position in Z (e.g. elevation) • M: Optional linear measurement (e.g. milepost) • Field mapping • Spatial Reference GISC 6382 Applied GIS UT-Dallas Briggs

  24. Spatial Reference • Spatial Reference • Coordinate system • Spatial domain • Precision • Cautions • All feature classes within a feature dataset share the same spatial reference. • Once created, the spatial domain for feature dataset/class cannot be changed. • Data outside extent of dataset need to be created in a new feature dataset or standalone feature class. GISC 6382 Applied GIS UT-Dallas Briggs

  25. Coordinate system • Projection system & parameters • Geographic, UTM and State plane • Datum, central Meridian, standard parallels, false northing and easting • Define Coordinate system for feature dataset/classes • Select: a predefined coordinate system • Import: from existing geodatabase • Create: a new coordinate system • Modify: current coordinate system • Save: for future use GISC 6382 Applied GIS UT-Dallas Briggs

  26. Spatial Domain • Spatial Domain • The allowable coordinate range for the geographic coordinates • X/Y Domain: • MinX, MaxX, MinY, MaxY • Z Domain: • Min, Max • M Domain: • Min, Max GISC 6382 Applied GIS UT-Dallas Briggs

  27. Precision • Precision • The number of system units per one unit of measure (of distance). Precision determines the resolution of a map (geodatabase) • For example: map unit is meter • Precision of 1: 1 system unit = 1 meter (resolution) • Precision of 1000: 1000 systems units = 1 meter • 1 systems unit = 0.001 meter = 1 millimeter (resolution) • E.g. Map unit feet, Precision of 12, Resolution? 12 system units = 1 foot 1 system unit = 1/12 foot = 1 inch (resolution) GISC 6382 Applied GIS UT-Dallas Briggs

  28. Determine Precision Based on Map Resolution • Formula: • Resolution = Map unit / precision • Precision = Map unit / resolution • Determine precision of a new geodatabase • Digitizing table resolution is 0.002 inches, map scales is 1:10,000, map unit is meter Geodatabase resolution = 0.002 inches * 10,000 = 20 inches 20 inches = 20 /39.37 meters = .508 meter ~ 0.5 meter Precision = 1 meter / 0.5 meter = 2 GISC 6382 Applied GIS UT-Dallas Briggs

  29. Geodatabase Storage and Precision Map units (Use) Floating Point 123.456 (m) • Coverage/Shapefile storage: • Single floating point precision (6-7 digits) • Double floating point precision (13-14 digits) • Geodatabase storage • As Integer: 4 byte integer • Stores 2.14 billion system units • max = 2,147,483,648 • Coordinate are • Multiplied by precision when stored • Divided by precision when used Multiply by precision 123.456*1000 Divide by precision 123,456/1000 System units (Store) Integer 123,456 GISC 6382 Applied GIS UT-Dallas Briggs

  30. 4 billion 200,000,000 mm x 3,750,000,000 mm y 2 billion 2 billion Check Geodatabase Precision with Range • Range in Map Unit (RangeMU) • Larger of width or height • Width = MaxX –MinX • Height= MaxY – MinY • Example • 1,000,000 – 200,000 = 800,000 (Width)  RangeMU • 4,060,000 – 3,750,000 = 310,000 (Height) • Range in system unit (RangeSU) • RangeSU = RangeMU * Precision • RangeSU = 800,000 * 1000 = 800,000,000 < 2.14 billion • Is OK to accept 1000 as precision? GISC 6382 Applied GIS UT-Dallas Briggs

  31. Re-center Coordinates using shift • Problem: • At desire precision, data is outside extent • Solution • Shift the center of geodatabase space to the center of the data • Shift = the difference between the center of your data and GDBCenterMU • Formula: • Center of geodatabase space in map units (GDBCenterMU) • (2,147,483,648/2)/precision = (2,147,483,648/2)/1000=1,073,741.824 • Center of your data • (DataMinX + DataMaxX)/2 and (DataMinY + DataMaxY)/2 • Shift • ShiftX = (DataMinX + DataMaxX)/2 – GDBCenterMU • ShiftY= (DataMinY + DataMaxY)/2 – GDBCenterMU • Update (MinX, MinY) with (ShiftX, ShiftY) GISC 6382 Applied GIS UT-Dallas Briggs

  32. 4 billion 200,000,000 mm x 3,750,000,000 mm y 2 billion 2 billion Geodatabase Storage and Shift Map units (Use) Floating Point 3,000,000.456 (m) • The geodatabase will • Subtract shift, then multiply coordinate by precision when stored • Divide coordinates by precision, then add shift when used Add shift 1,000,000.456 + 2,000,000 Subtract shift (3,000,000.456 – 2,000,000) Multiply by precision 1,000,000.456*1000 Divide by precision 1,000,000,456/1000 System units (Store) Integer 1,000,000,456 GISC 6382 Applied GIS UT-Dallas Briggs

  33. Subtype and Attribute Domain • Subtype • Attribute domain • Rang domain • Coded value domain • Associating domain with subtype • Attribute validation rules • Split and merge domain policies GISC 6382 Applied GIS UT-Dallas Briggs

  34. Why Subtypes and Attribute Domains • Data Integrity • Prevent illegal attribute assignment to features, tables with out-of-range data values • For certain critical field, provide predefined codes as the only valid values • Data Efficiency • Associate different subset of a feature class with different default values, attribute validation rules • Allow efficient choice from a set of valid value descriptions rather than manually input the value itself PowerPoles Streets Wood Steel Primary Secondary 20-30 30-50 ST, RD, AV, BLVD Ln, Cir, Pl GISC 6382 Applied GIS UT-Dallas Briggs

  35. Subtype • Subtype • Feature class’ “subclasses” that allow you to further distinguish objects without creating new feature classes • Logical groups of a subset of records within a feature class based on single column’s values • Same subtype has similar attribute values and behaviors • Create Subtype • Can choose default subtype • Require integer values (long/short), user adds descriptions • Can have different default values and domains for each field to improve data efficiency GISC 6382 Applied GIS UT-Dallas Briggs

  36. Domain • Define a set of legal values for a field’s attributes • Range: specifies a valid range of values for a numerical attributes • A water pipe must be between 1 and 100 inches wide • Coded value: specifies a valid set of values for an attributes. Can apply to any type of attributes • Parcels can only have RES or VAC land use values • Validation methods • Pulldown list of descriptions (coded values) prevents error • Validation during edit session prevents range error • A geodatabase property • Can apply to entire field or individual field subtype • Multiple objects in the same database may use the same domain • Cannot edit domain referenced by another subtype GISC 6382 Applied GIS UT-Dallas Briggs

  37. Creating Range Domains • Click on existing or blank domain • Enter the name and description for the domain • Enter the domain prosperities • Field type • Domain type: Range • Minimum value • Maximum value • Split policy • Merge policy 1 2 3 GISC 6382 Applied GIS UT-Dallas Briggs

  38. Creating Coded Value Domains • Click on existing or blank domain • Enter the name and description for the domain • Enter the domain prosperities • Field type • Domain type: Coded Values • Split policy • Merge policy • Enter the coded values • Code • Description 1 2 3 4 GISC 6382 Applied GIS UT-Dallas Briggs

  39. Associating domains to entire fields • Provide validation for records within a specified field • Domain must be defined as same field type Diameter_L is float Only float domain appear GISC 6382 Applied GIS UT-Dallas Briggs

  40. Associating domains to subtype • Provide validation for records within subtype • Domain must be defined as same field type Subtype field grouped into four codes Each code has its own domain for other attributes GISC 6382 Applied GIS UT-Dallas Briggs

  41. Editing records that have coded value domains • ArcMap only shows valid domain description • View codes in table by changing the appearance of the table GISC 6382 Applied GIS UT-Dallas Briggs

  42. Editing records that have range domains • Perform edit in ArcMap • Validate selection verifies fields with a range domain • Invalid features remain selected Angle has a range domain of 0 -359 GISC 6382 Applied GIS UT-Dallas Briggs

  43. Split Domain policies • Split policies on edited feature’s attribute default value geometric ratio duplicate Split Policy GISC 6382 Applied GIS UT-Dallas Briggs

  44. Merge Domain policies • Merge policies on edited feature’s attribute Merge Policy default value sum values weighted average GISC 6382 Applied GIS UT-Dallas Briggs

  45. Table Association and Table Join • Table association • Attributes about a feature can be stored • Feature class table (Feature class) • Separate table (Object class) • Associate tables with common column (key) values • Primary keys: Common field on original table • Foreign keys: Common field on destination table • Table join • Merge two tables together into one table logically or physically (in ArcMap). GISC 6382 Applied GIS UT-Dallas Briggs

  46. Relationship and Relationship Class • Relationship • Persistent and Dynamic association between objects in the geodatabase • Change to origin table can been seen when the destination access the relationship. • The relationship exist unless deleted. No merging of two tables • Common field with same data type • Between non-spatial objects (rows in tables) • Between spatial objects (features in feature classes) • Between spatial and non-spatial objects • Non relationship based on BLOB fields • No relationship based on location • Relationship class • A geodatabase relationship is stored in relationship classes. It is save as a record (row) in a relationship table. GISC 6382 Applied GIS UT-Dallas Briggs

  47. Geodatabase Relationship • Characteristics of relationship • Persisted relationship in the geodatabase • Can enforce dependent behavior • Can edit, query, and symbolized across relationship • Can only relate tables within the same geodatabase • Do not support access to stacked relationships • If A  B, BC; then A can not access C unless AC Origin Destination GISC 6382 Applied GIS UT-Dallas Briggs

  48. Creating Relationship Classes • Relationship properties • Relationship name • Origin and destination tables • Relationship type • Simple or composite • From-to, to-from labels • Messagingdirection • Cardinality (1-1, 1-M, M-N) • Foreign key, primary key GISC 6382 Applied GIS UT-Dallas Briggs

  49. Table Relationship Cardinality • Cardinality • Defines how many A objects are related to B objects • Influence relationship properties and uses • 1-1 (one-to-one) • 1-M (one-to-many) • M-N (many to many) Many parcels have many owners One parcel has one owner One parcel has many owners GISC 6382 Applied GIS UT-Dallas Briggs

  50. Relationship Type • Simple • Peer-to-peer relationship that are between two or more objects that exist independently of each other • Delete origin objects, related objects in destinations table continuous to exist – FK value is deleted • Can have one-to-one, one-to-may, or many-to-many cardinality • Composite • The life time of one object controls the lifetime of its related objects • Destination objects cannot exist without origin object • Can only have one-to-one, and one-to-many cardinality. GISC 6382 Applied GIS UT-Dallas Briggs

More Related