Chapter 4:Â Chapter 4 talks about map density and the importance of it. Map density is useful when mapping areas on a census or in areas in which vary greatly with size. It explains that in order for you to map density you use shades and the denser a population of whatever it is that you are mapping the darker it is. This chapter explains the differences between map features and feature values explaining t hat essentially the feature is what something is and the feature value is kind of like an adjective for the feature where it is just something that further describes the feature. It explains a couple of ways in which you can map density, the two ways in doing so are mapping density by defined area and mapping density by density surface. The density by defined area is used by mapping dots on the map and is largely considered to be less informational than mapping by density surface which uses blob type images. This chapter explains that you can compare areas to find something that reaches the goal of your map. One major thing this chapter tells you how to do is create a surface layer. These surface areas show you where about the points or line features are concentrated on the map that you are creating. It explains that the GIS calculates density by taking the cell size, search radius and units into account when mapping.
Chapter 5: This chapter explains the reasons in which we map the contents of the area in which the map is surveying. This is helpful regardless of if you are mapping single areas or many different areas at the same time knowing what exactly it is that your map is showing is extremely important. When you are defining what it is that lies within the mapped territory it is important that you summarize the information that you need and/or combine your map features with the area boundary and that in itself will create a summary of your data. Your data will consist of what? That is an important question before you summarize. What features are going to be in this map, what is it that is important for the audience to know? Another question that you will have to ask yourself is, are you features that you have created due to those data points going to be discrete meaning that they are unique and can be easily identified, or continuous which is a seamless representation of that data with no specific point? After you have asked those questions you will need a list, count, or summary to get an idea of what is inside of the area you are going to map. It explains whether or not you want to show feature of your map that are partially outside of your focused area or whether you would just map partial features like portions of rivers and other large features that could span a large area.
Chapter 6: This chapter explains that you should also map what is nearby your specified area this is because it is nice to know the travelling range to places. The traveling range to areas within your map are measured in distance, time, or cost. This is helpful for when you want to make a map that is explaining the distance from another feature the example in the book is streets within a three minute range of the local fire station. So for other maps that have that same type of purpose it is important to know how to calculate the distance of things from each other and the distance between features on your map. You can define distance or nearness based off of a feature’s travel costs. Something that it explains is that your maps come out in a way that is presented as flat. So, your information will be slightly skewed just due to the curvature of the earth’s surface. So the maps will contain something of a straight line distance which you get from specifying your distance and source feature. This chapter also explains what a buffer is and how you use buffers in order to make your distances more accurate. Basically it has the GIS draw around your distance due to the buffer which leads to more accurate distances. These buffers also show features in which are close to or at least near more than one source of information on the line of distance. Once the buffer is placed you can use the buffer to select features that fall within it.
