1. Attribute Data Input and Management
Chapter 6

2. Introduction Spatial and attribute Attribute data are stored in tables
Georelational data model stores spatial and attribute data in separate files, linked by feature id.
Synchronized.
Object-oriented data model stores spatial and attribute data in a single database.
No need to synchronize

3. Attribute Data in GIS
Georelational data model links spatial data and attribute data by id.
Attribute data stored in feature atttribute table which contains the id.
Row is called a record, column is called a field or an item.
Database management system (DBMS)
Info, dBase, Oracle, Informix, SYBASE, Access, FoxPro, SQL Server, etc.
Object-oriented embeds GIS into database

4. Types of Attribute Data
Character, integers, floating points (or real numbers), dates, time intervals.
Measurement scale
Nominal (named)
Ordinal (ordered by some attribute)
Interval (known interval such as degree)
Ratio (based on meaningful absolute zero)
Categorical (n and o); Numerical (i and r)

5. Types of Attribute Data
Data types and measurement scales are closely related.
Character for nominal and ordinal
Integers and real for interval and ratio, depending on decimal needs
Most GIS can convert numbers to characters and vice versa.
Watch! Normally text left, number right justified

6. Relational Database Model
Flat file (ascii or txt)
Hierarchical database (family tree example)
Network database (connections developed)
Relational
Key
efficient, independent, temporary link

7. Relational Database Model
Constructing a relational database
Why?
General ideas.
Sample of Northwind with Microsoft Access on your computer.
Normalization

8. Types of Relationships
One-to-one
One-to-many
Many-to-one
Source table
Destination table

9. Attribute Data Management Using ArcView
Two functions
join (one table)
link (both tables remain
virtual tables

10. Attribute Data Management Using ARC/INFO
JOINITEM
one-to-one
many to one
permanent
exactly same item key
RELATE
temporary
CURSOR for “link-like”

11. Attribute Data Entry Field definition Methods of data entry data width
data type (must match GIS package)
number of decimal places
include spaces for negative sign and decimal point
Methods of data entry
avoid manual
import if possible

12. Attribute Data Entry Methods of data entry
UPDATE (one record at a time!)
look up table
take advantage of relational data model
use user-friendly cut and paste and then import

13. Attribute Data Verification
Woe is me!
Linked to spatial data
Accuracy of attribute data
Range and validity checking
Printing
Re-entry and compare
Expert spot check

14. Creating New Attribute Data from Existing Data
Simplify by reclassification
new field
select and fill
repeat
Attribute data computation
computation
weighting