Chapter 1 , Introducing GIS analysis
GIS is constantly changing due to the rapid evolution of new technology. GIS is evolving because people are finding new uses for GIS. It is becoming more than just mapmaking. GIS for analysis can be applied to many field to get the most accurate data and information. GIS analysis is defined as looking for patterns in your data and at relationships. Simply making maps is a form of analysis. Steps important to analysis are listed: ask a question, understand the data, choose a method, process the data, look at the results. I enjoy lists and found this useful. Some parts are self explanatory. Understanding the Data requires finding information on what kind of data and how specific it is to determine how fit it is for the project. Looking at results includes stuff like deciding what information is helpful. Discrete: the feature’s actual locations can be pinpointed. Continuous: the features blanket the entire area you are mapping and aren’t pinpointed to one location. Summarized data represents density of individual features within area boundaries. Categories are groups of similar things. Ranks put features in order. Counts are actual number of features. Amounts are a measurable quantity associated with a feature. Ratios show the relationship between 2 quantities. Categories and ranks are set number values within the given data layer. Calculating and summarizing are different. Calculating evolves assigning new values to features and summarizing involves using data tables to find a piece of data. This chapter contained a great overview of GIS and these were the points that stood out to me. I would be curious to see at the end of this course whether these concepts were the most important things in this chapter.
Chapter 2, Mapping where things are
This sections covers the actual placing of articles on a map compared to the introduction found last chapter. Mapping the locations of individual features allows you to see the distribution of the feature as well as the patterns that may help mapping. It is important to create a map that shows features relevant to yourself and the audience. There are many things you can alter to help. Only included relevant data and have clear concise categories. Geographic coordinates and codes must be assigned; you will need to assign them if they are not in a GIS database. You can map single features by repeating a symbol which may reveal patterns to your audience. You can choose subsets of your features to map. I enjoyed the example of all crime vs. burglaries to help understand the concepts. Using different symbols can show different category within your data. You can adjust the size and range of your categories to adjust the way GIS displays your map. Keep in mind that the map needed to be discernable. Stick to less than 8 colors or symbols. Adjusting the grouping can help help keep the map clean and remain under 8 categories. Choose symbols with define shapes and colors. All of these are key to making patterns visible to your audience. I really enjoyed learning the different parts that go into making a map. This makes me view maps differently because I can imagine how simple it could be to manipulate data. I also am grateful for the opportunity to learn GIS somewhere where I can learn the ethics behind GIS as well as the application.
Chapter 3, mapping the most and the least
This chapter focused on mapping based on quantity associated with each feature. There was a lot of information present and was difficult for me to understand and summarize. It adds more information than mapping features. There are several options for displaying most and least depending on what type of feature you are looking at. Simply put, you can “map quantities associated with discrete features, continuous phenomena, or data summarized by area.” . Discrete features are defined as individual locations, linear features, or areas. Next, this chapter discuses how the context you are mapping effects the look of your map. . When exploring data you can map as many features as is helpful for you in pattern recognition. When presenting this should be streamlined and made ‘cleaner’. Ratios are created by dividing one quantity. Averages are used to compare those with few features to those with many. Proportions show you how much of a whole each part represents. Densities show the concentration of features. Cases are created in 4 basic way natural breaks, quantile, equal intervals, and standard deviation. Which one use use depends on the data. Graduated colors and symbols are use similarly. You can also use small chats such as a bar graph or pie chart. They can cause issues identifying patterns if not used in the right context. contour lines are used to show rate of change such as elevation or precipitations. 3d renderings can allow the audience to better understand the change of a continuous phenomena. Perspective can be influential when using 3d models. This chapter was very definition heavy but I feel the concepts are easy to understand but hard for me to describe.
Chapter 4 mapping density
Mapping density shows you the highest concentration of a feature. By simply mapping features you could see patterns in density however density mapping allows for you to see the visual difference easier. They are most commonly used to map areas such as population. There are two ways to map density you can go based off of area or density surface. each method has positives and negatives and it is important to pick the method based on your data. The chapter goes into detail about dot density maps and the proper way to display dots to be impactful but still effect in showing the data. I do not see the appeal in the dot density. Other methods seem better than others but hopefully going through this course I will understand the benefits of all types of modeling. Density surface is created using a raster layer. from my understanding it creates a new layer that overlays the gradient on the map. It is noted that this method takes more time. This process uses graduated colors and contour lines. The chapter goes into very specific details regarding the process behind making these density maps. I will likely use this chapter as a reference. My thoughts were quite scattered while reading this. There is a lot of information on may different aspects that I do not fully comprehend.