Chapter 1:
This first chapter really goes over what GIS analysis is and the key points associated with it. GIS is really helpful when it comes to getting and creating data and mapping. Although it doesn’t just involve mapping, that is a big factor. First and foremost, GIS is a process that helps you look at geographic patterns in data and the relationships between certain features. This can involve both simple and complex methods.
There is a bit of a process in terms of analyses. Those include framing your question, understanding your data, choosing a method, processing all of your data, and finally looking back at all of the results to see how this may be of value to you. In the process of understanding geographic features, the chapter goes over the different types of features – discrete and continuous. There are also two ways of representing this which involves vector and raster models. Summarized data is also important to note in this chapter.
It’s important that every bit of data that you are collecting should be in the same map projection and coordinate system. Map projections are going to translate your locations onto a globe, while coordinate systems go into specifics to locate features within a two-dimensional space. Both of these work together to help enhance your data for the GIS analysis.
There are 5 different attribute values for geographic features – categories, ranks, counts, amounts, and ratios. Categories are similar things grouped together. Ranks are the features put into order, going high-low. Counts and amounts kind of go hand in hand with each other and they are going to help you find the total numbers. Lastly, ratios are going to show the relationships between two different quantities.
One last thing that was important in this chapter was the 3 different operations for features and values in tables which were selecting, calculating, and summarizing. Again, this chapter in general just kind of goes over what GIS is and the features that are connected with it/how you can use it.
Chapter 2:Â
Chapter 2 goes over a lot about how you can use GIS for mapping and why mapping is useful. Mapping can be used for all sorts of things for different job areas such as police using it to map crime, a store using it to map out where they put their newest location, or even wildlife biologists using it to keep track of certain animal studies.
When creating a map using GIS, there are lots of steps that are important and you need to make sure they are done correctly so that your map comes out the way you want it to. The very first thing that you need to do is figure out what you want/need to map and what information you are going to need from the analysis. As said before, it can really help you find all sorts of different features and locations and that just depends on the type of information you are wanting to get out of it. The map should also cater to the proper audience. The amount of information and categories on your map is going to depend on who you are trying to target. Make sure you have all of your geographic information prepared before diving into the mapping itself. Some maps are going to be smaller with less categories which is fine and some are going to be larger. You want to make sure that it’s not too big or too small so find a good medium that will still be good for your specific research. This chapter also dives into assigning your geographic coordinates as well as category values. For the categories this means that each feature needs to have some sort of category and pattern. You can map either a single type or by category, and again, this just depends on what you are using it for. For a single type you would use the same symbol for all your features whereas for categories you would want to use different symbols for each category. Chapter 2 dives into more detail about both of those as well, but I won’t write out all of the details of both of those. A good rule of thumb when mapping categories is that you don’t want to display more than 7 different categories. This is because it becomes too confusing on one single map. If you do have more than 7, that’s when you would want to start grouping them together and the possibilities for different groups are endless.. It’s up to you what sections you put them in! When choosing your symbols for the map you can do colors, shapes, or both. Colors are easier to identify than shapes, especially on a smaller scale. You should be able to clearly see the different patterns and information on the maps if they are done correctly. This chapter overall went into a lot of detail on how you can start mapping and what it can be useful for.
Chapter 3:
In the third chapter, you learn a lot about the things you need to map and understand the quantities and patterns associated with creating maps. First off, mapping the most and least helps you find places that meet criteria, or to see the different relationships between places. It is important to note that you should map patterns of features with similar values. There are 3 different quantities you can map – discrete features, continuous phenomena, or data summarized by area (it dives into each of those in detail as well). Quantities can be counts or amounts, ratios or ranks. Knowing which one you are using is important. After deciding your quantities it talks about classes – you can assign each individual value a symbol or put them into classes. Individual mapping is a bit more detailed and accurate because you can look at each feature separately, but classes are better for when you have a bigger selection of features. When using classes, there are 4 common schemes: natural breaks, quantile, equal interval, and standard deviation. To figure out which is best, just look at your data distribution!
The chapter goes into a ton of detail about the 4 schemes including what they are and how to use them. In order to determine which scheme to use, it’s good to create a chart or spreadsheet of some sort to evaluate your data. If you have any outliers (which could happen) – there are a few different ways you can deal with it. One of which is grouping them together into their own class. After you decide everything with the schemes, it’s important to (with the help of GIS) decide on how many classes and make it easier to read them once they’re finished so you can easily interpret them.
Making maps is another big section. GIS gives you these options when creating maps – graduated symbols, graduated colors, charts, contours, and 3D perspective views. It goes into detail for all of those and when choosing your map it’s important to know those features and data values. You can look for all sorts of different patterns within your maps and each of the different options from above have different features/quantities that set them apart from the others. Overall this chapter I think went into the most detail regarding each section and it really helps the reader understand why we map things and all the little details that go into making them.