Chapter 4:
The beginning of chapter four talks about map density and how map densities are specifically used for finding patterns within the mapping; it also goes into depth about deciding what to map based on the data that you have. There are two ways of mapping density which are by a defined area, and by density surface. The chapter then goes into more depth about mapping density for defined areas which requires calculating a density value for these to find areas. The equation used for this is: population density = total population /(area/2787840). Further into the density for defined areas it talks about the dot density map And continues about the individual features that map density has for those to find areas. Next to the chapter talks about creating a density surface it goes into explaining the idea behind what the GIS does with the surface. In this portion there are a lot of calculations that need to be done such as cell size. For these calculations there are three different steps that need to be calculated in order to get that information. The next part of the chapter goes into displaying a density surface which pinpoints colors used for the maps. It suggests that because of the surface layering that there should be graduated colors to show the variation in the units that you are describing. it also goes into the ideas of Contours which are connection points of equal density that show the rate of change across surfaces. Lastly this part of the chapter talks about looking at the results and how you can understand and analyze the data that is being presented.
I really thought this chapter was very thorough. I am interested to see how we apply the calculations in this class because at first glance these calculations seemed a bit difficult to understand without knowing or seeing multiple examples of how those calculations are supposed to be used.
Chapter 5:
Chapter five starts off with why map what’s inside, it goes to the idea of being particular about what you’re deciding to bring to the data set. It talks about crimes that you can see in a certain area as well as toxic plumes. Understanding why someone would want to have this data set for future reference. Next it goes further into defining your analysis so going more into depth about what you can see and pull out from the data set especially if you’re looking at different areas in the book there’s single areas as well as multiple areas that are being discussed. therefore depending on what area you’re looking at it can determine what patterns or information you need to pull from it. After looking at the single and multiple areas it goes into the idea about are the features inside discrete or continuous. This just goes into the further investigation of the area to see if there is a big impact or less impact to the surrounding area. Following that explanation it goes into what information you will actually need to pull out from the data set starting off with the idea about needing a list count or summary. then going into more of the Strategic analysis of do you need to see these features that are completely or partially inside the area. This goes into the idea of the borders around that area and if something’s on that borderline do you count it or do you not count it. It was really interesting to see the comparing methods on page 147. This was really helpful in kind of the breakdown of what can be pulled from these maps and how they can aid in data analysis. The rest of this chapter just goes more in-depth about what can be found inside certain areas and features based on the data set and what information can be pulled based on the information that is present.
Chapter 6:
Chapter six starts off with talking about why map what’s nearby. meaning why expand the area that you’re looking at but then only focus on the smaller aspect. For instance if you are looking at an analyzing a small neighborhood but you also have the outside roadways to see the traveling range of certain areas. then the book goes into how you’re measuring these areas and what measurements you should be using. They’re also different distances or cost ranges that you might need; these are inclusive rings and distinct bands. both of these pinpoint areas that you want your perspective audience to look at to grasp the data set that you are pulling from. In this chapter there was also discussion about creating a buffer within your map to make it more clear about where the information is coming from. There was also discussion about layering of information colors and more. especially when it came to creating distance ranges in various color layers.
It was interesting to see on page 217 how you can have a bigger map but then designate two different areas of that map to have data point sets therefore you can kind of do a comparison about seeing certain data. On page 229 it was interesting to learn about the calculating cost over a geographic surface. I didn’t really know what this was and so it is interesting to learn that this is as stated from the book “Calculating cost distance over surface lets you find out what’s nearby when traveling overland.” I thought this chapter was really informative and gave really clear information about GIS mapping and the various maps that you can create and what data you can pull from those maps.