What is the Terrain Visualization feature?
The terrain visualization tool allows a user to view color renderings of elevation, slope, and aspect data derived from Digital Elevation Models (DEM).
- Map services and data available from U.S. Geological Survey, National Geospatial Program
- 1/3 arc second ~ 10m x 10m cell resolution
- The DEMs were retrieved from the online Global Data Explorer, courtesy of the NASA EOSDIS Land Processes Distributed Active Archive Center (LP DAAC), USGS/Earth Resources Observation and Science (EROS) Center, Sioux Falls, South Dakota, http://gdex.cr.usgs.gov/gdex/
- 1 arc second ~ 30m x 30m cell resolution
Calculating slope in a GIS environment is strictly derived using from data from a Digital Elevation Model (DEM).
The scale at which a person can analyze a slope with an inclinometer is not at a level to be compared to using raster DEM data files.
- For a given point, a slope value is calculated using its eight neighboring data points.
In the United States, our DEM’s have a 10 meter resolution, so each data point represents the average elevation of a 10 meter by 10 meter grid on the ground.
Yes, there are plenty of couloirs that have sections 50+ degress, etc. but is it sustained over an area to be captured at a 10 meter resolution?
A terrain feature has to be at a scale that can be defined by the ‘x’ meter grid resolution for it be visible in an elevation dataset. Only then could that terrain feature be represented in the derived slope dataset. DEMs are at a defined scale for GIS analysis; a hiker or skier can certainly read the terrain at much finer scale.
The Terrain Visualizations and the data from which they are calculated can be inaccurate. They should not be relied on as a sole source of information when making critical decisions in the outdoors.