Index Value Plot

Index value plots pick a certain value to measure variables against. The example above shows the average stream flow index of New Mexico over a ten year period. The stream flow value that was set for normal this example was four. Above four meant New Mexico was too wet and below four was too low.

http://waterwatch.usgs.gov/?m=real&w=plot&r=nm

Correlation Matrix

Correlation matrices are designed to take two variables and show the similarity between the two. There 100% similarity in the diagonal line because you are comparing a variable to itself. You must read below and above the diagonal to see how similar variables are to other variables. The rainbow colored key on the right explains the % of similarity, red being very similar and purple being not alike at all. This example is showing the correlation between 'the cluster moments of electrons.'

https://particle.phys.uvic.ca/twiki/bin/view/AtlasUVic/ClusterStudies

Digital Elevation Model

A digital elevation model (DEM) is one that shows the topography of land using remote sensing or land surveying. The model above is a DEM of New Mexico. There key is a key below the map that tells you the elevation of certain areas depending on their color. However, with the DEM it is easy to see the different elevations without a key.

http://edac.unm.edu/wordpress/2008/06/

Digital Line Graph (DLG)

A digital line graph (DLG) is a graph that digitally altered in order to show geographic structures more clearly, such as roads, lakes and mountains. The above map was taken of the Lake Tahoe Basin. The red outline is of surrounding roads. You can also see the outline the lake and lines that indicate where streams are going into the lake. DLGs help us to know where geographical features are located.

http://tahoe.usgs.gov/DLG.html

Continuously Variable Proportional Circle Map

A continuous variable map is one where each circle represents an actual number. It is unlike range-graded in that there can be an infinite number of circles. The graph above is showing the newspaper endorsements that each candidate got in the 2008 election. There are two size circles shown in the key and by that you can see the number of endorsements in each region. These graphs are good when an actual number is known rather than being estimated.

http://infochimps.org/static/gallery/politics/endorsements_map/endorsement_graph.html

Isopleth

An isopleth is a line that connects points with equal variables. The map here contains several isopleths that are showing the average annual trichloroethylene (TCE) concentrations in Dayhoit, Kentucky. The closer the isopleths are together the stronger the TCE concentrations. Using these isopleths it is obvious to tell exactly where the majority of the concentrations are coming from.

http://www.stonelions.com/Dayhoit.htm

Digital Ortho Quarter Quads (DOQQ's)

A digital ortho quarter quad (DOQQ) is an image that is taken from an Aeriel photo and then digitized. This gives it an accurate scaling. After being tweaked by the computer the image is no longer displaced by the terrain like it was before in the photo. The above photo was taken of lake Wynn, WV.

http://www.geomart.com/products/geodata/doqq/index.htm