Data and Documentation
The accepted framework layer for the elevation dataset in Montana is the USGS National Elevation Dataset. The National Elevation Dataset (NED) is a raster product assembled by the U.S. Geological Survey. Both the one arc-second (approximately 30-meter) and one third arc-second (approximately 10 meter) data have been collected and processed for the extent of Montana. NED data access (DEMs)
USGS 3DEP in Montana
Montana needs a State department or an Organization to take on the MSDI Elevation Stewardship role to best leverage the USGS 3D Elevation Program (3DEP) initiative. MSDI Elevation Stewardship primarily involves leading the existing Elevation Working Group to elicit elevation needs and requirements and recording them in an MSDI Elevation Plan. GIS practitioners in Montana need to consider what their higher-quality elevation needs are that could be met through this USGS program.
With a Montana Elevation Plan in hand, USGS 3DEP resources are available to assist with regional or statewide aquisitions of high-quality, enhanced elevation data. The 3DEP initiative is being developed by the USGS to respond to growing needs for high-quality topographic data and for a wide range of other three-dimensional representations of the nation’s natural and constructed features.
Visit 3DEP in Montana for information about higher-quality data collection in the state.
Elevation data is a digital representation of spatially-referenced vertical positions above or below a datum surface. The data is most often used in grid (raster) form or via contour line data illustrating the elevation of the earth’s surface at defined intervals. Traditional Elevation Data is provided for use as products as well as source elevation data. Products include Digital Elevation Models (DEM), Digital Surface Models (DSM), Contours, and ancillary elevation products such as shaded relief maps. Source elevation data includes data like lidar point clouds (LPC) and ifsar radar returns.
Shaded Relief elevation data for visualization purposes is one of the most widely used geospatial data themes in the world. Elevation data is also used to model water flow, mass movement of material (avalanches and landslides), line of sight analysis, and flight simulation rectification of aerial photography, gravity measurements, and terrain analysis.
For reference, the two technologies identified below are commonly used to generate enhanced elevation source data capable of producing higher quality elevation data products (DEM, contours, etc.) and higher quality source data, enabling higher quality spatial analysis:
- Lidar—(Light Detection and Ranging): airborne lidar is a remote sensing method that uses light in the form of a pulsed laser to measure ranges (variable distances) to the Earth. These light pulses—combined with other data recorded by the airborne system— generate precise, three-dimensional information about the shape of the Earth and its surface characteristics.