Mid-Semester Lecture Exam

• Vocabulary• Obvious steps within GIS

– Selection and query processes– Working with tables– Classification concepts

• Projections– What are they – what do they change– Coordinates – how are they relevant

Home Work 1

• In ArcToolBox– Coversion Tools

• Import to coverage– Import from interchange file

• Define projection for coverage• In ArcMap

– Data• Export to shapefile

• Project shapefile to whatever you want

Dealing with an exchange format

• Data types – raster vs. vector• How does GIS differ from a mapping or CAD package• The three basic components of ArcGIS• Define vs Projection• Metadata• More questions about coordinates

– What information is critical for a coordinates to be relevant?

• Cardinality • When do you use a join and when relate?

Tables Continued

Adding Fields and Records

There are several data typesThere are two basic types common used:

Text Data Numeric Data

Left Justified Right Justified

Data Types

Text Date Short

Long BLOB

Float

Double

Smith 10/06/2003

14 165734 16.4 3429567.456

 

It is very important to choose the right data type.

ArcGIS can handle several tabular data formats:

• Coverages use an INFO format. These are an older format, cumbersome, but still frequently used.

• A shapefile uses a .dbf format. Much more sophisticated than an INFO file. We are currently using .dbf files in the lab exercises.

• Geodatabases uses a RDBMS format. Very sophisticated and powerful but more complex. We will use them in a few weeks time.

Very often you need a new field in a table.

Specify the Name and the Data Type

-32,000 to +32,000

-2 billion to + 2 billion

Integers – No Decimals

Precision is the number of digits to be stored.

Scale is the number of decimal places.

Numbers with Decimal Places

Date

Text

It is important to specify a length to accommodate your attribute but not too long.

Calculating a Value

The selected records are assigned the calculated value

Notice that text values are enclosed in double quotes

Calculating a Numeric

Convert from one data type to a different data type

Text type

Numeric type

Add a new numeric FIPS field then calculate the text field as a numeric field.

Create a New Table

Open the new table in ArcMap and then add data

You can use ascii files