Creating Data - Desktop GIS: Mapping the Planet with Open Source Tools - page 109

Chapter 8

Creating Data

Using existing data is fine and gives us a lot of capability—until we want
to display data specific to our area of interest. Sometimes we luck out
and find the data; other times we have to create or convert it. At some
point in your OSGIS career, you are going to need to do some creation
or conversion of data to get what you need. This is where you move on
from the hunter-gatherer stage in your GIS data usage.

Ways to create data suitable for our use include the following:

• Digitizing
• Importing from text files or other sources
• Converting data
• Importing GPS data
• Georeferencing an image

In this chapter, we'll explore some of the ways in which we can torture
data (whether raw or cooked) into submission and make it usable.

8.1 Digitizing

We've already seen examples of digitizing in the previous chapters. In
its nonglamorous form, digitizing is just tracing features, whether it
be on a digitizer tablet or the screen. This is a tried-and-true method
of generating new vector data from paper or a scanned image. If you
digitize from a scanned image displayed on your screen (as we did in
Chapter 5 , Digitizing and Editing Vector Data, on page 81 ) , it's called
heads-up digitizing—you've got to keep your head up and focused on the
monitor to do it. This method of digitizing has become quite prevalent