If you’ve used any raster DEM data to make maps you may have at one time or another asked yourself, “What is the appropriate map scale for the DEM I am using to make the map?” This question is tied closely to a basic principle of map compilation that you may have learned in your beginning cartography course: “Always compile your map from source materials of the same or larger map scales”. In our age of digital elevation models and other raster datasets, this basic principle of map compilation can be restated as: “Always create your raster map from data at the same or higher spatial resolution than the ground resolution of your map display grid cells”. The ground resolution of your map display grid cells will depend on the scale of your map. An equation you can use that relates map scale expressed as a representative fraction (1/x), DEM cell resolution, and map display resolution is:
1/x = 1 / (DEM cell ground size [cm/cell] × map pixel density [pixels/cm]), so that 1 centimeter on the map represents x centimeters on the ground.
To help you, we’ve summarized this information for some of the most widlely used DEMs in a table that you can download as a PDF from Mapping Center’s ArcGIS Resources – More page. A graphic of it is shown below.........
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