In chapter 5, which is entitled “Finding What’s Inside,” talks about what is in a GIS map that you do not see pictured directly on a map. The main non directly visual part of a map is the exact numerical data of the map. This is entered into a database, such as a spreadsheet, before it is made into visual data on a map. This keeps data very organized and together so that it can be worked with easily.
A couple of terms that I learned while reading this chapter were discrete and continuous. Discrete means that a part of a map is unique and identifiable, like a city. Continuous means that a part of a map is a seamless, or undefined, geographic object on a map, such as elevation change. Another technique that I learned was that you can take a given area and only map whole objects that are inside of it, or just the parts that go through it, or even the whole parts that are associated with part of it being in there.
In chapter 6, which is entitled “Finding What’s Nearby,” talks about how to use GIS maps to relate what is near a certain place, object or area. This can be done a couple of different ways. For example:
- By lines connecting the two
- By shadings that change their color as distance increases for an area
- By radius circles
- By symbols that represent a numerical distance
- By shaded travel ways by distance
Like everything else in GIS the creator of a map must know what to use on a map to make it work and picture what is trying to be conveyed. For example if you have a location and you want to know the radius of traveling twenty minutes from it in any direction. At first a straight line radius circle would be produced around the area, but this may not be realistic in the real world. Instead by mapping a only by pathways would give a more realistic area from the original location. In some places in a typical circle you may not be able to get to in twenty minutes, and also you may be able to get farther in straighter, more direct routes. In real world applications, such as map-quest, this is all that they do. They determine what the realistic distance between places is and how long it would most likely take to get there.
In chapter 7, which is entitled “Mapping Change,” discusses why maps change and how to map the change on them. Maps mostly only picture a certain point in time, and for maps to stay up to date they have to be constantly updated. Maps can picture this change on them by either having certain areas as different colors depending on the time that the data was taken or ignoring that there was a change picture it the same way as the original data. Also the data can either be communicative, like all the places where fire have happened in a town in history, or circular, like within a month seeing all the data for specific hour of the day. This ability over time seems to be a great way to do research, with the ability to divide data up on a time scale, and just not having a boatload of data that is not on a time scale at all. Even though this is not the only way to do research, it does put a whole new perspective on a data set.
