Luna – Week 3

Chapter 5 of the book talks about mapping “what’s inside.” This is useful because it can help to monitor those occurrences, compare those occurrences with others, and conclude when and how to take action. Areas are defined by drawing boundaries and data can be found in a single area or several and discrete (identifiable) or continuous (seamless) features. Which method is used can be determined by examining what kind of information the user needs from the actual analysis. Some examples of this information may be lists, counts, summaries, or feature views. This chapter discusses three different ways of finding the things inside of an area. The first way is drawing a map that shows the area boundary and the features to see what features are within the boundary. The second way is by specifying the area boundary and features for a summary. The last method is separating the area boundaries and features into different layers, overlaying them, and having the system combine and compare to make summaries. This chapter next discusses how to actually draw the maps, talking about using/mapping locations, lines, discrete areas, and continuous features. Then, it talks about choosing the features that the user wants to use within a boundary, which can be done by the GIS. These results can then be compiled into a report or spreadsheet in many kinds of summaries, including the popular ones of count, frequency, and numeric attributes (sum, mean, median, standard deviation, etc.). Lastly, this chapter talks more about the method of overlaying, discussing the two big categories of using this method with discrete areas and continuous categories. The continuous way uses one of the two methods: vector (compares cross areas) or raster (compares cells). After reading this chapter, I feel more comfortable with the concept of using areas and their contents to draw conclusions and summaries when mapping. 

Chapter 6 of the book talks about finding what’s around a feature, which is used to determine the area that is impacted by an event. First, the book explains the importance of specifically defining the analysis, which includes possibly determining distance, travel to and from, cost, and planes (whether it includes earth curvature or not). Next, the user must ask what information is needed from the analysis, which could be a list, count, summary, or distance/cost ranges (may need inclusive rings that show relationships between totals and distances or district bands that compare distances to other attributes). Then, the chapter explains the three ways of discovering what’s nearby, which include straight-line distance (creates a boundary/selects characteristics at a set distance), distance or cost over a network (finds what’s within a manageable distance/cost), and cost over a surface (finds overland travel cost). This chapter then goes very deeply into using straight-line distance, talking about the potential of making and using buffers, just choosing features within a certain distance and the different ways to do/use that, using the GIS to find the distance between features and how to obtain/utilize the results, or creating a distance layer in the program and using it to create specific distance buffers. Next, the chapter talks about measuring over an entire network in the GIS, which means that the system finds all lines in a network within certain parameters. To do this, the user may have to specify the layer for the network, assign segments to centers, set travel specifications, choose surrounding features, and make the final map. Lastly, this chapter talks about finding cost in a geographic surface, which involves specifying cost, personalizing cost distance, collecting the information, summarizing the results, and creating the final map. This chapter was a bit more abstract for me, but I’m sure the concepts will be more clear once we’re using these skills. 

Chapter 7 of the book talks about mapping changing conditions or movement in order to predict future happenings, choose a method of action, and interpret the effects of some kind of policy. The first topic in this chapter is defining the analysis, which then goes into the types of change that can be mapped, which include change in location (discrete features and events) and change in character/magnitude (discrete features, data summarized by area, continuous categories, and continuous values). The chapter then moves on to the concept of measuring time, which can be mapped in one of three patterns: a trend (shows increasing/decreasing or direction of movement), before and after (shows impact of event or action), and a cycle (shows patterns in feature behavior). Time mapping can consist of showing the locations at multiple times or the data can be summarized. In both of these methods, the user must choose how many/which dates to include. Then, the user must determine what information they need from the analysis, whether that ends up being how much or how fast the data changed. Next, the chapter talked more about the methods of mapping change which are using a time series (uses snapshots), a tracking map (shows feature movement), or just measurements (shows difference in a characteristic). The book then explains these methods further, talking about ways in which each of them can be used to show change in both location and magnitude/character, methods in constructing the map itself, and how to examine/use the results. Finally this chapter concludes by talking about ways to report the results and methods in summarizing. This chapter was one that felt very straightforward. I found it useful that it showed ways to use each method as well as showcasing the pros and cons of each, which will be helpful when choosing what way to do things.