Sunday, March 23, 2008

Chapter 8 Bolstad- Attribute Data and Tables

Attribute data is the information that describes the non-spatial properties of objects. They are usually presented in tables with fields (vertical) and records (horizontal). This data summarizes the most important non-spatial characteristics of mapped elements. For an attribute table of counties, the fields might include the county name, population, area, and population density. Values for all of these attributes can be collected and presented in a table. It is then possible to conduct selections or queries on the data for analysis.

Tuesday, March 11, 2008

Monday, March 10, 2008

Chapter 6: Aerial and Satellite Images

Remote sensing involves measuring an object from a distance, either via a plane or a satellite. We use photographic or satellite images to gather spatial data. This data is based on the electromagnetic energy spectrum which is energy emitted from the sun. Sensors capture this energy when it is reflected.

Some advantages of this type of information are:
-raster based
-provides detailed geometrically accurate record (can take out distortion)
-broad area coverage

Two main types of distortion are terrain displacement and camera tilt. Both of these can be corrected. Orthophotography is the term for photos that have had distortion taken out.

Wednesday, March 5, 2008