What is a digital surface model – and how can they be democratized?

Digital surface models can help many industries, and new techniques are making them accessible to all. So, what is a digital surface model?

A digital surface model (DSM) can be extremely useful for a variety of industries and purposes. Creating a DSM has traditionally been resource-intensive, but new technologies are making it easier to build them.  

Key takeaways:

  • Many industries can benefit from using digital surface models
  • DSM’s were traditionally expensive and time-consuming to create
  • Read a definition of what a digital surface model is – and how it differs from other similar models
  • Learn how LuxCarta is using AI to create DSM’s of the Earth’s surface

For thousands of years, cartographers have endeavored to find the most accurate ways to represent the Earth’s surface. From using ropes to measure the contours of continents, to triangulation with surveying equipment, up to today’s satellite and aerial surveying systems. And digital surface models (DSM) represent the state of the art in this fascinating science. 

A DSM provides a highly accurate way of representing information about the planet’s surface, topography, and features. Creating a DSM has, until recently, required the use of high resolution sensors, which is an expensive and time-consuming process. However, new techniques are making it easier to generate these models, so any organization can build them. Let’s learn more. 

What is a digital surface model?

A DSM is one way to represent the Earth using digital technology. Digital surface models represent all features that are physically present on the planet’s surface. A DSM will show you information about:

  • Elevation data: Height and depth of the landscape
  • Topographic mapping: The arrangement of landscape features such as ridges, furrows, rivers etc., as well as slope and contour lines. 
  • Vegetation: A DSM maps everything on the Earth’s surface, so can include individual trees, tree canopies, brush, mangroves, crops, and other vegetation. 
  • Buildings and human infrastructure: A DSM will also represent buildings, bridges, roads, railway lines, and any other man-made structures. 

How are digital surface models used?

Digital surface models are used in a wide variety of industries and professions. Here are just some of the ways this powerful technology can be deployed:

  • Maps and surveys: For any organization that wishes to create accurate, detailed maps of a place, a DSM can be hugely beneficial. For example, many cities want to create 3D models for the purposes of land use planning. 
  • Forestry: Because DSMs show you how high above the ground tree canopies are, it can help with forestry management. Foresters could, for instance, use the technology to work out how tall trees in a sector are, without needing to physically visit and measure them. 
  • Environmental protection: DSMs can help with ecosystem monitoring, and tell you about land use change in wildernesses, coastlines, and other protected areas. 
  • Utilities: From planning the layout of power lines or solar farms, through to RF planning by telecoms firms, digital surface models show you where buildings and vegetation are physically located, so you can build around them. 
  • Insurance: Insurers can use DSMs to monitor and model risks from natural disasters. For example, a DSM can help calculate risks from river flooding, erosion, or rising sea levels. 
  • Military and defense: DSMs can help military planners generate a detailed picture of combat zones, and know where buildings, trees, furrows, ridges, ditches, and other landscape features are. 

DSM’s compared to other 3D models

Digital surface models share similarities with other kinds of 3D models:

  • Digital terrain models (DTM)

A DTM only shows the terrain, without showing buildings or vegetation on the surface. DTM’s are used in many sectors. For example, in hydrological modeling, they can show how water would move across a landscape without any distractions from more temporary features like buildings. 

  • Digital elevation models (DEM)

A DEM represents the bare earth, without any other landscape features or watercourses included. DEM’s only show slopes, elevations, ridges, and furrows with no more detail about what’s on the surface. Again, they can be useful in many scenarios. For example, engineers might want to use them to plan roads based on the flattest route.

For practical purposes, a “bare earth” DEM is generally synonymous with a DTM.

Simply put, a DSM creates a relief of the land including vegetation, buildings, and objects present. A DEM only shows the relief of the land. A DTM is a DEM that incorporates other geographical features such as ridges, breaklines, rivers, etc.

How are data collected to create DSMs? 

There are several ways that data is collected to build digital surface models. 

One of the older approaches (but which is still used today) is photogrammetry, which uses 2D images to build 3D maps. So long as you have a measure of the distance between two points on an aerial image of a place, it is possible to calculate the size of everything else on the map too. Today, software can do all these calculations. 

Since the early 2000’s, cartographers have often used LiDAR (light detection and ranging) to collect the data needed to produce digital surface models. This ingenious method involves an aircraft that is fitted out with a LiDAR system flying at a specific altitude over the chosen area. LiDAR works by sending a laser down to the surface, which then reflects back to the aircraft. Depending on how long it takes for the laser to reflect back, it is possible to calculate the elevation of surface features below. 

As a (very) simplified illustration, we can imagine an aircraft fitted with LiDAR flying over a field:

  • When flying over flat ground, it takes 2 milliseconds for the laser to bounce back to the aircraft
  • When flying over a ditch, it takes 2.1 milliseconds for the laser to bounce back, since the ditch is deeper than the field
  • When flying over a building, it only takes 1 millisecond for the laser to bounce back, since the building’s roof is much higher than the ground

As an aircraft flies over a landscape, the LiDAR system creates an enormous point cloud that shows the elevation data of everything it passes over. This information can then be fed into a DSM (a similar approach is used for creating DTMs). 

While this technique is very effective, it is also extremely expensive and time-consuming. Besides the need to use an aircraft fitted out with a LiDAR system, you would also need an extremely powerful computer system and software to process the data. As a consequence, access to digital surface models has often been restricted to governments, large businesses, and advanced research institutions. 

LuxCarta is democratizing DSM with satellite imagery

In recent years, new techniques have started to emerge which can help democratize DSM, making it easier and more accessible to organizations that wish to create digital surface models. One of the most effective approaches is to use satellite imagery. 

At LuxCarta, we have perfected a method for creating digital surface models using satellite imagery from high resolution sensors. Our AI-powered model is able to process a satellite image of anywhere on the Earth’s surface. The technology is able to automatically calculate accurate elevation data, and identify individual tree crowns and building height and shape. It then transforms this into a very precise 3D model. 

Using our method, it is possible for organizations to create DSM models of anywhere on planet Earth – from dense cities to rural farmland through to deserts and rainforests – all without needing to physically visit the place they’re interested in. 

Interested to see what a digital surface model is able to do for you? Contact LuxCarta today for an interactive demo of our BrightEarth DSM and DTM system.

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