A Digital Elevation Model (DEM) is a data set containing elevation values either in raster data form or in a Triangular Irregular Network (TIN). These data sets are commonly created through remote sensing techniques but can also be made through land surveying. This data is also regularly used in a GIS and is the basis for relief maps. The example shown above is the DEM of the contiguous United States. With this DEM, we are able to observe the commonly known mountain ranges of the U.S. (the Rocky Mountains in the west and the Appalachain Mountains along the east coast).
The World of Maps
Tuesday, April 3, 2012
DEM
A Digital Elevation Model (DEM) is a data set containing elevation values either in raster data form or in a Triangular Irregular Network (TIN). These data sets are commonly created through remote sensing techniques but can also be made through land surveying. This data is also regularly used in a GIS and is the basis for relief maps. The example shown above is the DEM of the contiguous United States. With this DEM, we are able to observe the commonly known mountain ranges of the U.S. (the Rocky Mountains in the west and the Appalachain Mountains along the east coast).
Black and White Aerial Photos
Infrared Aerial Photo
Infrared aerial photos are very useful to reflect the health of vegetation and also bodies of water. It can track temperature to monitor dangerous conditions in areas such as chemical plants and coal mines. Anything that gives off a heat signature can be shown on these amazing images.
Cartographic Animations
Cartographic animations are an important way of displaying results and falls with geovisualization. Having a time series of information can inform the viewer of things that aren't necessarily apparent when looking from image to image without the assistance of an animation. Trends become distinct as we see images before and after a single frame. This can even allow us to make predictions and forecasts based off of previous behavior. This animation is of Hurricane Andrew that struck in 1992. The animation shows the progression of the hurricane as it traveled across the state of Florida.
Dot Distribution Maps
These types of maps are an easy way to depict density of whatever
variable is being plotted. The visual clustering of dots shows a high
density of the variable occurring while large spacing inbetween the dots
shows low density values. This example shows earthquake locations for events between 1965 and 1995. The red dots are
shallow earthquakes, the green are intermediate depth, and the blue and
purple are deep.
Digital Raster Graphic (DRG)
Public Land Survey System (PLSS)
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