Sunday, July 17, 2011
Similarity matrices show how similar two elements are to one another. This is a similarity matrix for an experiment in which subjects had to search for a matching objects in a group of similarly-shaped items.
Star plots graph multiple variables at a time, one on each spoke. It is easy to see and compare many different data sets at once with a star plot. These star plots show the amount of various elements in the Turpin Basin.
Pie charts display data as parts of a whole. Each piece represents the percentage of the data. This pie chart shows the percentages of different religions in Lesotho. From the chart it can be seen that Lesotho predominantly Christian with the largest group being Roman Catholic.
A stem and leaf plot arranges a data set so that the mean and mode can easily be seen. This steam and leaf plot show the infant mortality rate in western Africa. It can be seen that the mean would fall somewhere around 113 and 114.
A box plot, sometimes called a box and whisker plot, provides a very concise summary of a data set. It shows the range; the 25th, 50th, and 75th percentiles; and the mean of the set. Very quickly judgements can be made about the skewness and distribution of a set of data. This is a box plot of a data set recording weight.
Histograms are used to show frequency of phenomena. The area of the rectangles is equal to one. This histogram shows the frequency of heights for 25 students.
Parallel coordinate graphs are used to show multiple sets of data at the same time and be used to show relationships between the various factors. This is a parallel coordinate graph that compares several types of cars and their characteristics.
A triangle plot is a graph that plots three variable simultaneously. A very common triangle plot is one that can be used to determine soil type. Soil, being made of three basic components, is plotted on the triangle and the percentage of clay, silt, and sand can be seen.
A windrose is a graphic that gives an overall analysis of the wind in a certain location. It shows a breakdown of the locations wind direction and speed. This is a windrose for the city of Fresno, California for the month of April and complies thirty years worth of data. From this graph you can see that the wind hardly ever blows from the northeast or southwest during the month of April, but does blow often and strongly from the northwest.
A climograph is a graph that shows the average temperature and precipitation for a location or region for each month. It allows for the viewer to quickly get an overall impression of a location o regions climate. This climograph is for Honolulu, Hawaii. As the graph shows, Honolulu's temperature is fairly the same year-round, but seems to have a dry and rainy season.
Friday, July 15, 2011
Population profiles, or population pyramids, depict a nations population in terms of age and gender. It can be thought of as two histograms put back to back and with it one can see how old or young a nations population is. This is the population pyramid for Spain in 2003. The largest age range was in their thirties. It can also be noted that the population is fairly even between men and women, except in the 80+ range women out live the men.
Scatter plots show relationships between two or more variables. They can be used to show positive, negative, strong, weak, or no relationships. This scatter plot shows a negative correlation to age and typing speed.
Index value plots are graphs that take the data set and create a base value for which all the other data points can be compared to. The graph above shows the percent change in CO2 emissions for the U.S. compared to the average.
The Lorenz curve, or an accumulative line graph, is an economic graph designed to show the unequal distribution of income in a given area. The equal distribution is graphed as a straight line, and the actual distribution is plotted over it. The degree to which the actual distribution line "sags" below the equal distribution is determiner of inequity. The graph above compares the inequity of China and Brazil's income in 2004. From these curves one could conclude that China had a more equally distributed income than Brazil did in 2004.
Bilateral graphs show two related sets of data simultaneously on the same graph. This graph shows both the average highs and lows for each month of the year in Australia.
Nominal choropleth maps used color to signify areas with similar characteristics or that belong in the same category. They do not signify numerical data or to what degree an area has a specific characteristic. For example, the map above labels countries as U.S. allies, Soviet allies, other communist countries, or none of the above. There is no gradation.
Unstandardized choropleth maps do not average the data they show. Each area unit, countries in the map above, is marked by the total number of a phenomena. In the map above the number of earthquakes is signified for each country.
A standardized choropleth map uses areally averaged data, such as population per square mile. The map above shows the number of property crimes per square mile in Milwaukee, Wisconsin in 1995 and could be used to track crime. Caution should be taken however in reading these maps because the size of each unit affects the perceived crime rate. A small unit with a few crimes may be a darker shade than a large unit that actually has more crime.
Univariate choropleth maps use color to show only one set of data. This map uses three classes to show a happiness index for the U.S.. The darker the green the higher the level of overall well-being.
Bivariate choropleth maps use color and sometime lines or patterns to show two sets of data simultaneously on the same map. This map uses two color scales, each with three classes to show the percentage of the population that is under 18 and the percentage of rural population in each district. Maps like this can be used to discover correlation between two phenomena.
Unclassed choropleth maps differ from classed choropleth maps only in the sense that there are not a set number of color gradations. The maps above compare classes and unclassed choropleth maps. On the left one can see that there are five classes to identify the percentage of people married by county. On the left there is no scale other than the darker the color the higher the percentage.
Classed choropleth maps use color to indicate the level of a phenomena in a region. The map is broken into areal units and the data within each unit is averaged. This map has six classes to show population density and the unit areas are outlined in black.
A range graded proportional circle map is the same as a continuously variable proportional circle map, except that the circles do not come in all sizes. There are only a set number of circle sizes. In this map, there are five circle sizes and they represent the number of emerging infectious disease events.
Continuously variable proportional circle maps use circle to indicate to what degree phenomena occur in a given area. The circles come in all sizes on a continuous scale. The map above shows rent rates in the northeast U.S. in 1990. The larger the circle, the more expensive rent is. There are not set sizes for the circles and they do not necessarily indicate where exactly the rent rate occurs.
DOQQs (Digital Orthophoto Quater Quads) are aerial photos with a resolution of one meter. The map above is an infrared photo with township lines marked. This type of image can be used to help plan for development and to determine land use.
DEMs (Digital Elevation Model) are digital representations of the Earth's surface. This is a DEM for the entire country of Switzerland. Depending of the level of detail, DEMs can be used for land development and assessment.
DLG (Digital Line Graph) uses the U.S. Geological Survey to create vector maps of various regions. They can show multiple layers of information from PLSS to transportation and utility lines. The DLG above shows road lines and topographical information such as terrain type and elevation.
Digital Raster Graphics (DRG) are scanned versions of U.S. Geological Survey topographical maps. The area within the neat line of the image is georeferenced so GIS information can be over-layed on the DRG image. This map is of a small portion of Austin, Texas. It shows several building outlines, property boundaries, roads, and rivers. This map could serve as a base for statistical data of the Austin area.
Thursday, July 14, 2011
Isopleths join areas of equal value. This isopleth map shows concentrations of trichloroethylene (TCE) in the river valley of Dayhoit, Kentucky. This can be used to track pollution, determine its sources, and help design a way to prevent it.
Isopachs are lines that connect areas with the same sediment or stratum thickness. This map shows the thickness of the Moscow Shale in northern Pennsylvania and southern New York with the dark blue lines. This map also contains information in the thickness of limestone in the same area. This map and others like it can be used to study erosion patterns.
Isohyets, like isolines, isotachs, and contour lines, link areas of equal value. Isohyets specifically connect areas with the same amount of rainfall. This map shows the rainfall in the Colorado State University area. Maps like this can be used to evaluate drainage systems and flooding damage.
Isotachs are lines that connect areas of the same wind speed. This map shows the surface windspeed for the U.S. on February 22, 2007. The arrows on the isotachs signify the direction of the air.
Isobars are a type of contour line used specifically in meteorology to show air pressure. Areas of equal pressure are connected with an isoline. This map shows a low pressure cell over the Great Lakes and can be used to predict weather patterns.
LIDAR works in much the same way as Dopper radar or sonar, but uses lasers instead. This gives LIDAR much more precision and accuracy in detecting distance. This is a high resolution LIDAR image of South Moloka'i Reef. This image was taken as part of an effort to assess the extent of damage in the reef. The green semi-rectangular area on the image is a hole in the reef.
Dopper radar uses radio or microwave radiation to determine the distance of certain objects or phenomena. This is a doppler image of a hurricane coming over the peninsula of Florida. It uses a color scale to show the intensity of the precipitation.
Black an white aerial photography uses film that is sensitive to wavelengths about the same size as the one detected by the human eye. This is an aerial photo of Flagstaff, Arizona. Photos like this can be useful for seeing what a city actually looks like, but also for overlaying with other forms of data and imaging.
Infrared photography uses film that is sensitive to wavelengths undetectable to the human eye. With infrared photography, it becomes easier to distinguish between vegetation types and even the difference between land and water become more apparent. This is an infrared aerial shot of the Sacramento Deep Water Ship Channel and Levees. There is a clear separation of water and land and one can tell that there are multiple types of land vegetation or terrain.
Cartographic animation combines maps and data to show change over time. They can show the change of a few hours or even the change over millennia. This is an image from an animation showing continental drift and how the continents moved from Pangea to their present day locations.
Statistical maps show statistical data visually by combining data with location. This map is a statistical map because it shows population with an almost bar graph-like design over a map of the U.S.. It makes it easier to see where most people in the U.S. live.
Wednesday, July 13, 2011
A cartogram portrays statistical data in terms of land area. For example, the map above shows which countries contribute to Walmart's products and revenue and to what extent. The larger the country, the bigger part they play. Countries that do not contribute at all are not shown. This causes the map to become extremely distorted, but makes for a dramatic display for the information.
Flow maps combine maps and data to show the movement of a certain item or subject. This map shows the traffic between Irish cities, particularly in connection to Dublin. The thickness of the lines determines the degree of traffic. The wider the line, the more traffic flows on that path.
Isoline maps are maps that use line to connect areas of equal value. Many isoline maps are used in meteorology to show temperature or air pressure. This map shows average annual precipitation in New York in inches. Areas with the same amount of precipitation annually are connected with isolines.
Proportional circle maps use circles of varying size to show the magnitude of a phenomenon in different areas. The circles do not necessarily signify the exact location of the phenomenon, but rather signifies to what degree it occurs. This map shows the number of internet user in European countries in 2004. The bigger the circle, the more internet users there are in the country.
Choropleth maps use color to signify certain phenomenon. They can be used to show average rain fall, temperature, or in this case, the varying climates of Australia. Each climate is assigned a color so that one can easily see where certain climates exist on the continent.
Dot distribution maps use dots to show the locations of various phenomena on the earth. One common dot distribution map is a population density map like the one above. Each dot represents a certain number of people and from the map one can see how the population (of Australia in this case) is distributed in an area.
Propaganda maps depict the world in the way that the cartographer desires to see the world. They can be used to spread ideologies about certain areas and mislead people into having biased views of a region. This map is a propaganda map because it gives the impression that Florida is full of sunshine, palm trees, and blonde bathing beauties, which perhaps is only true for a very small portion of the state. Even the caption "The Sunshine State" promotes the idealistic view of paradise.
Hypsometric maps use color gradation to show elevation. This is a hypsometric map of the island of Cuba. The color scale can be seen in the upper right corner. There are two independent color scales: one for land elevation and another for the ocean floor.
PLSS (Public Land Survey System) is the system that the U.S. uses to mark land distribution, ownership, and boundaries. Each state has at least one baseline from which 6 mile by 6 mile parcels of land are marked. Each of these parcels are further divided into 36 one square mile parcels. This map shows the PLSS for Oneida County in Wisconsin. Each square represents a 6 mile by 6 mile township. On this map a town can be made up of more than one township.
Cadastral maps show the boundaries and ownership of land. This map is part of the Public Lans Survey System for Portland, Oregon from 1852. (You can see the baseline at the top of the map.) It shows the boundaries and ownership of the parcels of land near the river as well as some topographical information.