Nair – Week 3

Chapter Five:

Chapter five focuses on mapping what’s inside a particular area. In the broad spectrum of things, this idea of mapping what’s inside seemed a bit irrelevant to me, but the chapter made it seem very important. People map what’s inside an area to monitor or to compare several areas to each other. It becomes easier for people to know whether to take action by observing what’s occurring in a region. The chapter also mentions that the first thing that we need to do is define our analysis and identify the type of our data. We can choose a single area or multiple areas for analysis. I think in places like India, where areas are divided into multiple sections(like pavements), it might be easier to get started with a single one and then move to multiple regions. Multiple areas include continuous (geographic phenomena) and discrete(unique, identifiable), like zipcodes and state parks. The mathematical terms, like list, summary, and count, used in Chapter three were also mentioned here as a way to use GIS to analyze information. Another thing the user can choose is whether to include features that fall completely outside/inside or partially a part of the area boundary. We can use GIS to overlay the protected area and the land cover areas.

Mitchell mentions the three ways of finding what’s inside, namely:

• Drawing areas and futures.

• Selecting the features inside the area. 

• Overlaying the areas and climate. 

Initially, each one of them is divided into their pros and cons using the compare table shown in chapter three. The chapter then elaborates on these three types throughout till the end and how they are related to discrete features. frequency, count, and how their results can be used. 

 

Chapter Six: 

 

Chapter six focuses on what’s nearby. Similar to chapter five, it goes in on the importance of certain aspects of geographic locations. GIS helps find out what’s occurring within a set distance of a feature. It helps identify the area and the elements inside that area that are affected by an event or an activity. Finding a traveling range which is measured using distance, time, or cost, helps define an area served by a facility. The chapter starts by asking the reader to define their analysis and identify their type of data. The author mentions that it’s also essential to choose if “what’s nearby” is set by distance or some other range. Distance is one way of deciding nearness, but it can also be measured using cost. In my mind, the word cost is always associated with money, but here it is used for time. One of the interesting things mentioned in the textbook is choosing whether to use a flat plane or use the curvature of the earth. 

The terms list, count, and summary from chapter three were mentioned again here to help the reader choose the best method of analysis. Distance and cost can be single or multiple ranges. Multiple ranges can either use inclusive rings or distinct bands. Like chapter five, There are three ways to find what’s nearby: 

• Straight line distance — Specifying the source feature and distance
• Distance or cost over a network — Specifying the source locations and a distance or travel cost along each linear feature. 
• Cost over a surface — Specifying the location of source features and a travel cost. 

The pros and cons are also mentioned to compare the methods and choose whatever is best for the reader. These three types were then further elaborated throughout the end by mentioning their subtypes and instructions, how GIS can be used for this, and how the result obtained can be analyzed. To me, this chapter was heavily similar to chapter five in the way it was structured. 

Chapter Seven:

Chapter seven focuses on mapping the change. Mapping change is very important as it helps find predictions that can be further used to take action. My TPG Draft Proposal Project for ENVS110 was based on predicting change(flood risk), so additional policies could be made to protect marginalized communities. To define the analysis, we need to understand the types of change. Geographic features can change in location or magnitude. Change in the location usually helps us see how features behave so we can predict where they will move next, for example, by forecasting hurricane patterns. Change in magnitude helps understand how conditions in a particular place have changed, for example, to observe land cover or vegetation in an area. Knowing the type of feature also helps choose the best method for mapping. There are two types of features — features that move and features that change in character or magnitude. Discrete features that can be tracked as they move through space and events that represent geographic phenomena are the two subtypes of moving features. Discrete features that change in the quantity of an attribute associated with them, Data summarized by areas that are quantities are associated with features within a defined area, Continous categories that show the type of features in a place, Continous values that are continuous quantities, for example, pollution levels, these are all subtypes of magnitude changing features. Three types of time patterns can be measured: 

• A trend that indicates whether something is increasing or decreasing. 
• Mapping conditions before and after an event lets us see the impact. 
•  Cycles show recurring patterns that reveal information about the behavior of the features. 

A snapshot or a summary can be used to display feature locations or characteristics two or more times. To map trends, determining an interval, the number of dates, and the total period can help. It is important to know how much and how fast the magnitude has changed after the analysis. There are three ways of mapping change: 

• Time Series – Good for showing the change in boundaries, values for discrete values or surfaces 
• Tracking Map – Good for showing movement in discrete locations, linear features, or area boundaries. 
• Measuring Change — Good for showing the amount, percentage, rate, or place. 

Similar to chapter five, the methods were laid down in a comparison table with their pros and cons to help the reader choose the best method for themselves. Next, the chapter gave instructions on creating a time series by showing the change in character or location. To create a tracking map, we can map individual features, linear features, contiguous features, or events. To measure and map changes types of character-changing features can be used. The chapter provides detailed instructions even for complicated situations, like mapping when there are negative values or if the boundary or category of definitions has changed.