Definition: What is data? Data is anything in the form of 1.Charts 2.Tables 3.Text 4.Maps 5.Photos 6.Imageries, etc.

Examples of data

Data vs. Information Data are collection of facts Data are observed/recorded It simply exists and does not have meaning of itself Information is obtained when the data is summarized/analyzed and the result is put into a meaningful context

Data vs. Information Data Information

Beyond Data & Information Data Information Knowledge Wisdom

Sources of GIS data 1.Existing Maps (analog & digital) 2.Remotely sensed data a. Photographs b. Satellite Imagery c. Lidar 3. Field observation a. Survey / Sampling b. GPS data

Most of the GIS data are now available online from respective State GIS data clearing house In NH (GRANIT): In VA (VGIS): In MA (MASS GIS): In NY:

Sources of digital data

Data format Most of the vector GIS data are in Shapefile (ArcView 3.x) ArcInfo interchange file (.e00) You have to use Import function in ArcGIS to make an ArcInfo interchange file usable!

Data format We will be using Geodatabase in this class Shapefiles can be exported to a feature class in a Geodatabase

Advantage of Geodatabase You can easily get the total length of Roads in NY! Feature class provides updated length of line feature

Advantage of Geodatabase Feature class provides updated area & perimeter of each polygon in a Geodatabase

What about area in a shape file? Shape file does not update the area of a polygon in the output layer You have to manually update it!