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      • Table of Contents
      • How to Highlight and Take Notes
      • Acronyms
      • Figures
      • Glossary
      • File Icons
      • Footnotes and References
      • Supported Coordinate Systems
      • Chapter One Title Page
      • Section One - Introduction
      • Section Two - What is GIS?
      • Section Three - Why Do We Need A GIS?
      • Section Four - Putting it all Together: An Example
      • Section Five - Uses of GIS
      • Section Six - History of GIS
      • Chapter Two Title Page
      • Section One - Introduction
      • Section Two - Geodesy
      • Section Three - Mathematically Measuring the Earth
      • Section Four: Latitude and Longitude - One Example of a Geographic Grid
      • Section Five: Geodetic Datums: Combining Reference Ellipsoids and Geoids
      • Section Six: Geographic Coordinate Systems
      • Section Seven: Projection Methods
      • Section Eight- Projected Coordinate Systems
      • Section Nine: Just a Few Extras
      • Chapter Three Title Page
      • Section One - Introduction
      • Section Two - Vector Data
      • Section Three - Raster Data
      • Section Four - Discrete and Continuous Data
      • Section Five - Data Tables
      • Section Six - Introduction to Attribute Tables
      • Chapter Four Title Page
      • Section One - Introduction
      • Section Two - Data Models
      • Section Three - Meet ArcGIS Pro Catalog View
      • Section Four - Meet ArcGIS Pro Maps and Layouts
      • Section Five - What Are Relational Databases and Geodatabases
      • Chapter Five Title Page
      • Section One - Introduction
      • Section Two - Attribute Tables: An Overview
      • Section Three - Attribute Tables Basics
      • Section Four: Selecting Data in ArcMap - The Basics of Making Selections
      • Section Five: Using Selected Data
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Section One - Introduction

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  • Chapter Six
  • Section One - Introduction

In GIS, we have two categories of data - primary and secondary data.  These are not unique terms to GIS, as many other sciences use these two categories, however, within GIS, the terms do have a unique meaning.  Primary data is created in one of two ways: either via digitizing from aerial and satellite images or collecting field data utilizing GPS-based collection devices, both methods of interacting with the Earth's surface in a very intimate and deliberate way.  Secondary data is any data which is produced as the output of a geoprocessing tool (the subject Chapter Seven).  Overall, primary data tends to carry a bit more weight, as it's not derived via a tool where error may be introduced through improper use of the tool, a misunderstanding of the tool or the data, or other similar errors (the topic of Chapter Eight).

In this chapter, we will look at the processes of manual and heads-up digitizing, a basic understanding of remote sensing, methods of taking paper maps and creating digital versions, converting postal addresses into geographic coordinates via geocoding, collecting data with smartphone based GPS apps and commercial GPS receivers, how to create data via crowdsourcing, and how to change existing data. The creation and correction of data are the two most common tasks a GIS technician does everyday, thus it is very necessary to have a solid understanding of the what and why of creating and editing data.