Skidmore Week 3

Chapter 5:
When mapping some people want to define what’s inside of an area to compare two sites or to see what’s inside a single area. A single area allows you to summarize data found inside or monitor the activity going on inside, whereas multiple areas allow for a better comparison between locations. Discrete features are those that are unique and continuous features are those that are seamless that can be summarized for a whole area. There are three types of information you can obtain a list, count, or a summary which wholely depends on the information needed. Some features may be partially inside of an area so you may exclude them in the case of a summary but in a list or count you will want to include them. Drawing areas are good to see a few features within a selected location. Selecting features is good for lists or summaries within a selected area. Overlaying both of these data is a combination and is good when comparing more than one area. Once all of the above has been considered the next step is drawing the map. If you are mapping linear features you can use a single symbol by creating a category. Discrete locations depend on whether your focus is on the inside of the location or just the area itself, but you will want to label these features. If mapping continuous features you will want to map the data and then place the area lines over top to separate the inside from the outside. In some GIS software, you will be able to select locations within the area and highlight them which can allow for better analysis. When doing your analysis you can count, find the frequency, or summarize a numeric attribute. Maps using areas with discrete features can use a linear model whereas maps using continuous features have to use a vector or raster model to show the data.

Chapter 6:
When mapping in GIS you may want to find what’s nearby to a location to find what’s within a certain distance which can be used by planners. To define nearness you can set a distance or a specific location. In a set distance the data is linear whereas a specific location or time is found to be geometric data defined by data limits on your map. When mapping distance curvature of the Earth can be chosen to be included or not depending on the creator of the map and the data. Much like the last chapter since the data being mapped is an area the information that is needed can be found in a list, count, or summary. Inclusive rings are when all the data within a range is included whereas distinct bands show data differently within each band. Straight-line distance is good for finding what’s within a boundary, distance or cost network is good for finding data that follow a linear path, or cost over a surface which is good for calculating overland travel. In a straight-line distance model, you will need to create a buffer to define your area and select the data you will want. In a distance surface model, you will use a raster model where each cell could have a potentially unique value. In a distance or cost network, the GIS software used will have an updated street map you will use but also will need you to define the layer used and the center starting point. Much like the distance over the surface model, the cost over surface model uses a raster model but each cell would define a certain cost rather than the distance from the center point.

Chapter 7:
Mapping allows you to better predict the future by seeing where things have been and predicting where they could be going. There are two types of change being mapped, location and magnitude both of these can be discrete or continuous. Time can be measured as a trend, before and after, or a cycle these each can be used for different analyses. Snapshots show the conditions in a given moment of time whereas summarizing is showing discrete events that are happening or not. When mapping trends you will need to set dates and intervals which may already be defined by the data you have collected or you will need to set them yourself. When doing your analysis you either calculate their amount or rate of change. A time series is used to show the changes in boundaries, a tracking map shows the movement in discrete locations, and measuring change shows the amount of change in a place.