The 10,000 km2 project was carried out in collaboration with the City of Ottawa, the City of Gatineau, NRCan, the National Capital Commission (NCC) and the Province of Ontario and supported by the Emergency Management Strategy for Canada. This includes the entire area of both the National Capital Region and the Ottawa River, areas that are highly vulnerable to flooding. With the addition of this data, 61 of Canada's 100 largest cities are covered by the HRDEM product and the HRDEM Mosaic. The data is distributed across eight provinces: British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec, Nova Scotia and Newfoundland and Labrador (see map below). The total area of high-resolution elevation data derived from LiDAR is now nearly 500,000 km². A DTM represents distinctive terrain features much better because of its 3D breaklines and regularly spaced 3D mass points.Natural Resources Canada (NRCan) is pleased to announce the release of over 100,000 km2 of new data in the High-Resolution Digital Elevation Model (HRDEM) and HRDEM Mosaic. From these regularly-spaced and contour lines, you can interpolate a DTM into a DEM. In the image above, you can see how the DTM is not continuous and that it’s not a surface model. The DTM points are regularly-spaced and characterize the shape of the bare-earth terrain. For example, contour lines are in purple. A DTM augments a DEM by including linear features of the bare-earth terrain.ĭTMs are typically created through photogrammetry as in the example above. A DTM is a vector data set composed of regularly spaced points and natural features such as ridges and breaklines.
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READ MORE: Free Global DEM Data Sources – Digital Elevation Models SOIL MAPPING: DEMs assist in mapping soils which is a function of elevation (as well as geology, time, and climate). This is useful when planning a highway or residential subdivision.
TERRAIN STABILITY: Areas prone to avalanches are high slope areas with sparse vegetation. HYDROLOGIC MODELLING: Hydrologists use DEMs to delineate watersheds, calculate flow accumulation and flow direction. A bare-earth elevation model is particularly useful in hydrology, soils, and land use planning When you void vegetation and man-made features from elevation data, you generate a DEM. The built (power lines, buildings, and towers) and natural (trees and other types of vegetation) aren’t included in a DEM. When you filter out non-ground points such as bridges and roads, you get a smooth digital elevation model. VIEW OBSTRUCTION: Urban planners use DSM to check how a proposed building would affect the viewshed of residents and businesses.Ī digital elevation model is a bare-earth raster grid referenced to a vertical datum. VEGETATION MANAGEMENT: Along a transmission line, DSMs can see where and how much vegetation is encroaching. RUNWAY APPROACH ZONE ENCROACHMENT: In aviation, DSMs can determine runway obstructions in the approach zone.
Because objects extrude from the Earth, this is particularly useful in these examples: Digital Surface Model (DSM) – Extruding features are tree canopy A DSM captures the natural and built features on the Earth’s surface.Ī DSM is useful in 3D modeling for telecommunications, urban planning and aviation. But height can come from the top of buildings, tree canopy, powerlines, and other features. In the end, LiDAR delivers a massive point cloud with elevation values. Hence, how this system earned its name of Light Detection and Ranging. When the pulse of light bounces off its target and returns to the sensor, it gives the range (a variable distance) to the Earth.
In a LiDAR system, pulses of light travel to the ground.
What is a Digital Surface Model (DSM)? Airborne Light Detection and Ranging (LiDAR)
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