Tuesday, April 3, 2012

DOQQ

    
     A Digital Orthophoto Quarter-Quadrangle (DOQQ) is an image that has been geometrically corrected so that the distance between two point is the true distance. They are recognized as one of several critical geo-spatial data sets needed to effectively manage and use geographic information systems in statewide, regional and local databases and spatial applications. This example shown about is part of the Farmville NE DOQQ. Maps of this type are often put into a GIS and are used to make vector data files.






DLG


      A digital line graph (DLG) is a cartographic map feature represented in digital vector form that is distributed by the U.S. Geological survey (USGS). DLGs are collected from USGS maps and are then distributed in various scales, and can have up to nine different categories of features depending on the chosen scale. This DLG example shows a section of Ottawa, Canada transformed into a digital vector form. This type of graph can be put into a GIS and used to maintain databases of relevant information.

Doppler Radar


     Doppler radar is a tool that makes use of the doppler effect to track objects at a distance. This type of technology is most commonly used in meteorology; more specifically used in tracking storms. Doppler radar allows us to pick up a storms size and speed; it can give us this information even days before it hits and area. The doppler radar shown above shows the size and speed of Hurricane Ivan before it hit the Gulf coast. The colors represent the intensity of the storm with red being the strongest.

Univariate Maps


     A univariate choropleth map is a type of thematic map in which the non-location data is all of the same kind; they only display a single variable. Population density, annual rainfall, and birth rates are all examples of univariate data. This map example shown represents the percentage of Americans living in poverty in different rural countries within the United States in 2008; people in the south seem to have higher poverty rates than those living in the north.

Unstandardized Choropleth Maps


     Unstandardized choropleth maps are thematic maps which contain data that has not been areally-averaged, though it still allows comparison between variables. This example shows the predictions of the 2008 Presidential Election. It displays the number of electoral votes of each state and is colored (red for republicans, blue for democrats) to indicate which candidate those electoral votes are predicted to go to.

Bivariate Choropleth Map


     A bivariate choropleth map is a thematic map that displays two variables or statistics by using two different sets of symbols or colors in order to illustrate a relationship between the two variables. This example shows the population density and percentage change in that population over a period of time in Russia. This is is considered a bivariate choropleth map because it is displaying the relationship between two variables, population density and percentage population change, and a different color scheme is being used for each variable.

Unclassed Choropleth Map

    

    

     Unclassed choropleth maps are similar to classed choropleth maps; however, unclassed choropleth maps do not have an averaged statistic towards each particular color. If you wish to create a map that maintains the data relation, unclassified data theoretically does a better job than classified data because unclassified data allows us to maintain the numerical relations between data. This means that the color shades on an unclassified map are directly proportional to the values of each enumeration unit; there are many shades of each color to show the diversity of the statistics. This unclassified map contrasts the democrats (blue) from the republicans (red). Most states are not completely republican or democratic so there are many shades of the combined blue and red which make a purple hue.