Digital Elevation Models

Orthorectification, Obstruction Modeling And 3-D Point Clouds

Digital Elevation Models: Orthorectification, Obstruction Modeling And 3-D Point Clouds

Terrain modeling is a critical foundation for many geospatial applications such as orthoimagery generation and site modeling. CompassData generates high-quality terrain models in a variety of formats and from a variety of sources. Our DEM may be used for orthorectification of satellite imagery, volumetric calculations, and relief map generation. CompassData is also capable of creating DEM for use in the growing 3D mapping industry.  CompassData provides Digital Elevation Models as a stand-alone product or as a portion of ground control and imagery deliverable.

  • As a MAXAR satellite imagery reseller, CompassData has ready access to a wealth of stereo imagery that can be used to construct elevation data
  • CompassData was one of the first U.S. companies to employ a state-of-the-art aerial imaging system, the XCAM Pod dual camera pod. It can be rapidly deployed on all types of aircraft, enabling on-demand elevation data collection anywhere in the world
  • As insured and rated sUAS Pilots with a fleet of fixed-wing and multi-rotor platforms, CompassData can generate very dense, detailed, terrain models from overlapping images
Example Digital Surface Model created using a satellite stereo image pair (GeoEye 1 sensor).

A valuable aspect of LiDAR and UAS imagery is the creation of “point clouds”. The elevation points can have feature attributes and even color assigned to them. For instance, the colorized point cloud (below) was generated from the overlapping mono images collected by a UAS. Not only do the points have x, y, z values, they typically can be assigned attributes such as “pine trees”, “scrub oak”, “cottonwood”, “grass”, “house”, which can be used to aid in the analysis and for editing the elevation points to make a DEM.

A digital elevation model or DEM is a digital model or 3D representation of the surface of an object, commonly the Earth or another planet, the moon, or an asteroid. DEMs are created from terrain elevation data. A Digital Surface Model (DSM) is a specific type of DEM in which the earth’s surfaces including all inanimate objects are represented. A Digital Elevation Model (DEM) represents the bare ground surface without any objects like buildings and vegetation. Both types are useful for different applications. CompassData is well versed in the techniques used in DEM production such as land survey, photogrammetry, remote sensing and LiDAR data analyses. Contact us for more information on Digital Elevation Models.

A Digital Elevation Model (DEM) represents the bare ground surface without any objects like buildings and vegetation. Both types are useful for different applications.

Applications:

  • Floodplain Mapping; In September 2013 the Front Range of northern Colorado was severely impacted by what meteorologists termed the “thousand year rain”. CompassData was in the field weeks later collecting hundreds of control points for FEMA LiDAR mapping. The resulting DEMs will be used to re-establish flood plain models.
  • Volumetric calculations (how much material was removed from a pit mine over the past month?)
  • Elevation change detection (are there new buildings surrounding an airport?; or how much has the new highway overpass changed the drainage patterns?);
  • Aviation obstruction data (does the new cell phone tower potentially pose an obstruction at the regional airport?).

Here at CompassData, we are well-versed in all of the various techniques used in the production of DEMs, including photogrammetry, land survey, LiDAR data analysis, and remote sensing.

Knowledge Base and FAQ: Digital Elevation Models 

What are DEM?

In short, a digital elevation model (DEM) is a digital model or 3D representation of the surface of a terrain. These models are most commonly based on the earth’s surface using terrain elevation data. Terms that are often used interchangeably with “digital elevation model” include “digital surface model” and “digital terrain model.” Typically, a digital surface model represents the surface of the earth, as well as objects, like buildings and vegetation. A digital terrain model usually only shows the ground surface. The term “digital elevation model” is commonly used as a generic term that encompasses digital surface models and digital terrain models.

Digital elevation models are typically prepared using remotely-sensed image data and data that survey teams have collected. A DEM may be represented as a vector-based triangulated irregular network (TIN), or as a raster, or a grid of squares that are also referred to as a height map when used to depict elevation.

What are DEM (and How Are They Used?)

Terrain modeling and DEM are critical components in a number of geospatial applications, including site modeling and orthoimagery generation. At CompassData, we generate high-quality terrain models from a number of sources and in a variety of different formats. Digital elevation models from CompassData can be used for relief map generation, volumetric applications, and orthorectification of satellite imagery.

Despite all of the potential applications of digital elevation models, you may still be wondering what they are and how they are used in real life situations. Read on to learn the answer!

DEM Applications

Digital elevation models can be used in a number of real-world applications. One common use is for volumetric calculations. For example, digital elevation models can be created to determine the amount of material that was removed from a mine within a specified period of time. These models are also useful in detecting changes in elevation. Digital elevation modeling is also frequently used in the rectification of satellite imagery and aerial photography. Other uses and applications for digital elevation models include:

• Creation of 3D models, such as raised relief maps
• Terrain analysis
• Engineering and infrastructure design
• GPS
• Surface analysis
• Flight planning
• GIS
• Floodplain mapping
• Aviation obstruction data

Digital elevation models are extremely useful for city modeling, visualization, and landscape modeling. They are absolutely essential for drainage and flood modeling, land-use studies, and other geological applications.

Learn More About Digital Elevation Models