Mitchell Chs. 5-7

Ch. 5

To find what’s inside-

Draw an area boundary on top of the features, select the features inside and list or summarize them, or combine the area boundary and features to create summary data.

Can also find out about multiple areas, discrete or continuous.

Three Ways of Finding What’s Inside

Drawing the areas and features

Selecting the features inside the area

Overlaying the areas and features

Many different ways to color and organize the maps depending on your emphasis.

Using the Results:

Count

Frequency

Summary of a numeric attribute (sum, average, median, standard deviation)

Vector vs. Raster Overlay

Vector: more precise measure of a real extent

Raster: more efficient, but less accurate depending on the cell size.

Ch. 6

Finding out what’s within a set distance identifies the area-and the features inside that area-affected by an event or activity.

Finding what’s within a set distance also lets you monitor activity in the area.

Traveling range is measured using distance, time or cost. Finding out what’s within traveling range of a feature can help define the area served by a faculty.

Knowing what’s within traveling range can also help delineate areas that are suitable for a specific use.

Distance is one way of defining and measuring how close something is.

The information you need from the analysis: List, count or summary

How many distance or cost ranges do you need??

Inclusive rings: useful for finding out how the total amount increases as the distance increases.
Distinct bands: useful if you want to compare distance to other characteristics.

Three Ways of Finding Out What’s Nearby

Straight-Line Distance:

specify the source feature and the distance and the GIS finds the area

good for creating a boundary or selecting features at a set distance around a source

Distance or Cost Over a Network

specify the source locations and a distance or travel cost along each linear feature.

good for finding what’s within a travel distance or cost of a location, over a fixed network

Cost Over a Surface

specify the location of the source features and a travel cost.

The GIS creates a new layer showing the travel cost from each source feature.

good for calculating overland travel cost

use straight-line distance if you’re defining an area of influence or want a quick estimate of travel range

use cost or distance over a network if you’re measuring travel over a fixed infrastructure to or from a source

use cost over a surface if you’re measuring overland travel

Ch. 7

Mapping change is important in preventing catastrophe, planning and analyzing what happened in the past.

Change in location helps map out where things may move in the future, like weather.

Change in character or magnitude maps the change in values, like population.

Features that move:

Discrete features are mapped as they move through space, like the path of animals.

Events usually do not occur in the same place, but mapping them can help see where the events tend to move, like drug traffickers.

Features that change in magnitude/character:

Discrete features again, like store sales each month

Data summarized by area, values in a defined area that can change, like population.

Continuous categories show the type of features in a place, like land cover

Continuous values show things that are monitored at all times, at fixed points, like weather.

Time can detect trends, conditions before and after an event, and a cycle.

Time analysis can tell you how much something changed and how fast it changed.

Tracking maps can map individual features, linear features, contiguous features, and events.

Mitchell Chs. 2-4

Ch. 2

Maps can be used to describe more than just where things are.

 

Mapping locations of features allow researchers to find the patterns behind what causes these features, such as plant types with rainfall, erosion etc. -When looking at a map, there are two important questions one must ask;

 

What information do you need from the analysis? Depends on you are looking for.

 

How will you use the map? Having a very detailed map can be useful, but only information pertaining to what needs to be checked is useful.

 

Assigning Geographic Coordinates

Whether the map is new or old, having coordinates of different parts of the map is very important. Whether this is an address or long/lat values is specific to the map, but without coordinates the map is just a jumble of information.

 

Assigning Category Values

With maps with different types of features, these features needs to be distinguishable, and within that, have a different code for mapping.

 

Within many maps are major types divided into subtypes. An example could be how toxic water might be based on the color on the map.

 

Single Type Mapping

Single type mapping is using the same symbol every time.

 

These are simple patterns, but these maps could be all one needs to describe simple features.

 

The GIS of this uses coordinates to map out the patterns. Look at page 26 in Mitchell for a good example.

 

Subsets within single features can also show patterns. The book uses an example on crime where all crimes are shown and then certain crimes are taken away to show different patterns like burglaries.

 

Mapping by Category

Takes simple maps and adds different types of information to it.

 

The GIS behind the mapping stores different pieces of information in different sections.

 

 Mapping by category allows for mapping by type as well.

 

Categories/Grouping

When categories are mapped, the different types of subcategories must be grouped with the main one.

 

With these groups comes turning some categories on and off to show more important information in greater detail.

 

With the categories also comes how the viewer perceives the information. An uninhabited zone could be any number of things, but a forested area is a forested area.

 

Grouping the categories can be done in three different ways

Two codes: one for detailed and one for general

Creating a table to distinguish between detailed and general

Assigning the same symbol to the various categories that comprise each general category.

 

Colors and Symbols

When describing a map, using different colors allow the reader to easily distinguish between categories. Many maps use similar colors for each subsection.

 

Widths can also play an important role.

 

Using text can also help explain a map. If some areas could be misunderstood, adding text sometimes can erase the confusion.

 

Ch 3. 

Mapping the most and least allows you to cross-reference material and data to fit your needs, or discover patterns and trends among your info. 

 

Mapping the data based on quantities goes beyond just graphing data to a certain location, by adding the additional layers, you see what areas pertain to your question.

 

Features- knowing what features you are mapping is also very important. Graduated colors are used when there is a continuous phenomenon, or when the area is not simply defined.

 

To Broaden or to Generalize-  whether you are exploring the data, or presenting a map.

 

Counts and Amounts- counts and amounts show you the total numbers.

    A count is the actual number of features on the map.

    An amount is the total of a value associated with each

        feature.

 

Ratios- shows the relationship between two quantities, and are created by dividing one quantity by another.  The most common ratios are averages, proportions, and densities.

 

 Densities show where features are concentrated.

 

Ranks- used to sort the importance of something from highest to lowest, or vice versa.

 

Mapping Individual Data- helpful when first examining data because you get an accurate view without all the other distractions.

 

Classes/Breaks- using classes and breaks unifies a group of info into a universal set of numbers that can be graphed.

 

There are 4 types of classification schemes:

Natural Breaks- Classes are based on natural groupings of data values.  This system associates data where there are jumps in values, and pairs them in the same break value.

Quantile- each class contains an equal amount of features, but the values may be different.  Some values may be extremely high or lower than the norm, but could be placed in a class where the values are varied greatly due to the number of features.  Good for emphasizing the relative position of a feature among other features.

Equal Interval- the difference between the high and low values is the same for every class.  Class breaks are an even, set number for all.  Good for mapping continuous data,

Standard Deviation- This requires you to find the median of your information, as well as the standard deviation, and then break classes by adding or subtracting the standard deviation to the median.

 

Choosing a Classification Scheme- When choosing what scheme to choose, you must take into account many factors including, how your data is distributed across it’s range, as well as looking at outliers, and finding how to best fit them in your class.  Most of the time natural breaks are good for taken care of outliers, which could throw your whole scheme off balance.

 

Making a Map- Once you have decided how to classify your data, you must find the correct map projection for it.  The types of maps used are: Graduated symbols, Graduated Colors, Charts, Contours, and 3-D Perspective Views.

 

Graduated Symbols- used to map discrete locations or lines.  Graduated point symbols are drawn at the locations of individual features to show the magnitude of the data value. 

 

Ch. 4

Mapping the density of features lets you see the patterns of where things are concentrated

 

Helps you find areas that require action or meet your criteria, or monitor changing conditions

 

Why Map Density?

Mapping density shows the highest concentration of features

 

Useful for looking at features and mapping areas of different sizes

 

Simplifies the graphic portrayal of individual locations by deriving the number over a specified area

 

Mapping density is especially useful when mapping areas, such as census tracts or counties that vary greatly in size

 

Deciding what to map…

Know what kind of data you have

 

Density mapping of point and line features are mapped using a density surface

 

Can map data that has already been summarized by defined areas

 

Can either map the density of features, or of feature values

 

Can create a density map based on features summarized by defined area, or by creating a density surface

 

Mapping density for defined areas

Dot map, or calculate a density value for each area

 

Dot Map

Represents the density of individual locations summarized by defined areas

 

Each dot represents some number of phenomena

 

Random distribution of dots per area – they do not represent actual numbers for that one locality

 

The closer the dots, the higher the density

 

Density portrayed graphically, not numerically

 

Creating a density surface

Usually created as a raster layer

 

Each cell in the layer gets a density value based on the number of features within a radius of the cell

 

Provides the most detailed information, but requires more effor

 

Can create a density surface from individual locations, or linear features, such as roads or streams

 

Point data may be:

Locations of features, such as customers, crimes, or eagle nests

Sample points you’ve collected data for, such as water quality samples across a lake

Mitchell Ch. 1

GIS- 30 years old, recently becoming widespread

GIS analysis- find out why things are where they are and how things are related

Maps- used to clearly and accurately present the information from the data

Most common uses of maps

To map:  where things go

     the most/least

     density

     what’s inside

     what’s nearby

                             change

Steps of GIS analysis 

Framing the question- determining what information you need

Understanding your data- determined by the type of data that will determine the specific method used

Choose a method- decide which method to use based on your original question and how the results of the analysis will be used

Process the data 

Look at results- results can be displayed as a map, table or chart based on what information used and how you group your values

The type of geographic features you’re working with affect all steps of the analysis process

Discrete- the actual location represented by a spot based on line location

Continuous- i.e. precipitation levels.  There is no set border.

Summarized by area- represents the counts or densities of individual features within area boundaries the data value applies to the entire area but not to any specific location within it i.e. demographic data

Ways to represent geographic features

Vector- each feature is in a row in a table and feature shapes are defined by x,y,z locations in space features can be discrete areas defined by boards are represented when analyzing vector data analysis involves summarizing the attributes in the layer’s data table.

Use continuous categories or discrete features when combining with other layers 

Raster- features are represented as a matrix of cells in continuous space each layer represents one attribute and analysis occurs by combining the layers to create new layers with new cell values the cell size is important because it will affect the results of the analysis and how the map looks using use discrete features, data summarized by area and continuous numeric values           

Map projections- translate the locations on the globe onto the flat surface of your map get distortion because shapes of features being displayed, measurements of area, distance, and direction

Coordinate system- specifies the units used to locate features in 2-D space and the origin point of those units

Categories- groups of similar things help organize data values represented using numeric codes or text

Ranks- puts features in order from high to low applied when direct measurements are difficult down side its relative to the order of value

Counts and Amounts- show the total number 

Schurrman

I ordered the text the first week of classes, but it has yet to come in. I’d buy a copy from the bookstore, but I don’t have sufficient funds. Which sucks and makes me angry. I hate the mail system here…

GIS applications

1. Tracking migration routes

Biologists use collar transmitters and satellite receivers to track the migration routes of animals to help design programs to protect them. The information from the transmitters and receivers allow a map to be made displaying these routes.

2. Underground mining

“This application of GIS in underground mining concentrates in four technical areas: land ownership and mineral claims, exploration management, production, and mine safety. The benefits of consolidating and archiving claim data and the ability to georeference property maps defined in local coordinates into state coordinate system is of paramount importance to a land and exploration manager. In the production area, GIS facilitates the optimal sighting and querying of service installations relative to production centers to meet the production parameters. In mine safety, the sighting of refuge chambers relative to production centers is optimized and areas of potential safety concern are identified utilizing GIS’s proximity analysis. The same applies to finding the shortest route to emergency exits and preparation of maps to facilitate the prompt evacuation of mine personnel.”

3. Resource Management

“Resource management is the efficient and effective deployment of an organization’s resources when they are needed. Such resources may include financial resources, inventory, human skills, production resources, or information technology(IT).”

Introduction to Myself

My name is Kim Sinclair.  I am a senior Geology major with a minor in Mapping.  I plan on persuing Geophysics in grad school, along with applying GIS applications.  I love soccer, swimming, and volleyball.  I have more information about me here.