Attribute Data Input and Management
A column is called a field. Page 2. AGS 722. AGS 722. ? Most GIS projects have many attributes
Advanced GIS
attribute data tells you what it is. Metadata describes both geospatial and attribute data. In GIS we call geographic data as GIS data or spatial data
TRAINING MODULE - Basic GIS and Web Mapping Training
Introduction to GIS (refer the PowerPoint presentation) . MODULE -2: CREATE EDIT AND MODIFY SPATIAL AND ATTRIBUTE DATA .
Chapter 8. ATTRIBUTE DATA INPUT AND MANAGEMENT 8.1
8.1 Attribute Data in GIS. 8.1.1 Type of Attribute Table. 8.1.2 Database Management. 8.1.3 Type of Attribute Data. Box 8.1 Categorical and Numeric Data.
GIS-Based-Planning.pdf
Soil Map Drainage Map
GIS based Master Plans in Andhra Pradesh - Status
Base maps (attribute data) for all ULBs in available with the department with. 100 layers as per AMRUT guidelines. • GIS BASED MASTER PLANS INITIATED.
Geographic Information System (GIS) What is GIS?
GIS operates. Software. Provides the functions and tools required to store analyze
Principles of Geographic Information Systems—An introductory
To this end the GIS allows data entry
A New Approach for Data Conversion from CAD to GIS
21 thg 6 2014 symbology
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Attribute Data Input and
Management
Attribute data describe the characteristics of
the map feature.Attribute data are stored in tables
Each row of a table represents a map feature.
Each column represents a characteristics.
The object-oriented data model stores both data in a single database, but can distinguish spatial data from attribute data.AGS 722
Linking Attribute Data and Spatial Data
The georelational data model store spatial
data and attribute data in separate files.Each map feature has unique label ID (Figure
6.1). Linked by feature ID, the two sets of data files can be queried, analyzed and displayed. Attribute data are stored in a table called feature attribute table (Figure 6.2).A row is called a record.
A column is called a field.
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Most GIS projects have many attributes.
To store all attributes in a single table is not
efficient both time and computer space and difficult to use and update.A database management (DBMS)system
provides tools for data input, search, retrieval, manipulation and output to manage, integrate and share the database.Most GIS packages include DBMS:
- INFO for Arc/Info - MS Access for IDRISI, ArcView andArcGIS
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An Example of IDRISI Attribute Table
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Soil Geodatabase in ArcGIS
Spatial Data
Attribute Data
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Types of Attribute Data
Defined by data types allowed in GIS
package. -Character string -Integers -Real numbers -Dates -Time intervalAGS 722
Defined by measurement scale
-Nominal:describe different categories -Ordinal:data that differentiate data by ranking relationships, e.g. low, medium, high. -Interval:data that have known intervals between values, e.g., temperature 40C is warmer than 0C. -Ratio:same as interval but have meaningful or absolute values, e.g. population density of0 means no population in the area.
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Nominal and ordinal data can be grouped as
categorical data. Interval and ratio data can be combined as numerical data.Measurement scales are important for data display
and analysis in GIS.They affect the choices of map symbols.
GIS analysis often involves computation, which is limited to numerical data.Data types and measurement scales are related.
- Character strings are suitable for nominal data - Integer and real numbers are appropriate for interval and ratio data.AGS 722
The Relational Database Model
A database is the collection of interrelated tables in digital format (Figure 6.3).A relational database is a collection of tables (relations) which can be connected to each other by keys.
A key: one or more attributes whose values can uniquely identify a record in a table.- A key common to two tables can establish connection between corresponding records in the tables (Figure 6.3).
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Normalization
Normalization is the process of breaking
down a table into small tables while maintaining the necessary linkages between them.Purposes:
- To avoid redundant data in the table. - To maintain and update data effectively in the separate tables. - To facilitate distributed database. 7AGS 722
Steps in normalization
First normal form:The table will no longer has
multiple values in the cell (Tables 6.1, 6.2).Second step:Break down the table into small
ones, some redundancy still remain (Figure 6.5).Final step:New tables are created no
redundancy exists (Figure 6.6).AGS 722
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Types of Relationships
Three types (Figure 6.7)
- One-to-one relationship:one and only one record in the destination tableis relate to one and only one in the source table.
- One-to-many relationship:one in the destination table may be related to many records in the source table.
- Many-to-one relationship:two or more in the destination table may be related to one record in the source table.
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Designation of the source and destination
tables depend on the data stored in the tables and information sought.See examples in Figures 6.8 and 6.9
Attribute Data Entry
Field definition
- Define data width, data type and number of decimal place.Methods of data entry
- Import existing data - Typing and use look up table.AGS 722
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Attribute Data Verification
Check to make sure that label ID is unique and
not contain null values.Check the accuracy of attribute data.
Verification can be done by:
- Print and check manually - Use validation rule such as in ArcGIS 12AGS 722
Creating New Attribute Data from
Existing Data
Attribute Data Classification
- Reduce a dataset into a small number of classes, e.g. slope classesAttribute Data Computation
- Perform computation with the existing data, e.g. create population density from population/area.quotesdbs_dbs17.pdfusesText_23[PDF] attribute data management in gis ppt
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