Mapping with Drones: Photogrammetry and LiDAR
Drone mapping or aerial surveying in the construction sector provides maps as the end deliverables. Two common methods for drone mapping are photogrammetry and LiDAR. Each method produces different mapping outputs and requires specialized data processing software for analysis. This article will explore the types of maps typically generated from drone surveys or mapping.
Overview of Photogrammetry
Photogrammetry is a method of mapping using photographs taken from a drone. It allows for 3D models to be created from overlapping images taken from different angles. These images are then analyzed using specialized software such as Pix4D or Agisoft Photoscan to create 3D models with accurate measurements. Photogrammetry can be used to create orthomosaics, digital surface models, and point clouds.
Overview of LiDAR
LiDAR, or Light Detection and Ranging, is a type of drone mapping that uses lasers to measure distance. It is particularly useful for creating digital elevation models (DEMs) and digital surface models (DSMs). The laser pulses emitted from the drone are used to measure the distance from the surface to the drone and create a 3D point cloud. The point cloud is
Types of Maps in Drone Mapping
The common types of maps obtained from drone mapping are:
- Orthomosaic maps
- Digital Elevation Models (DEM)
- Digital Surface Models (DSM) and Digital Terrain Model (DTM)
- Contour line maps
- 3D point clouds
1. Orthomosaic Maps
Overview of Drone Mapping
Drone mapping or aerial surveying in construction provides the end deliverables of maps. Two of the most common methods for drone mapping are photogrammetry and LiDAR. Both methods offer different mapping outputs, and require specialized data processing software in order to analyze the data. This article will provide an overview of the types of maps that can be generated from a drone survey.
Understanding Photogrammetry
Photogrammetry is the process of using photographs to create 3D models, measurements, and maps. A drone is used to take overlapping photos from a variety of angles, which are then fed into specialized software such as Pix4D or Agisoft Photoscan. This software will be used to generate 3D models, orthomosaics, digital surface models, and point clouds.
Exploring LiDAR
LiDAR is a remote sensing technology that uses laser pulses to generate 3D maps. LiDAR is a fast and accurate method of mapping large areas, and produces incredibly detailed maps of the surveyed area. LiDAR data can be used to generate digital elevation models, 3D point clouds, and even 3D models of the surveyed area.
Generating Orthomosaics
An Orthomosaic map is a top-down view of a survey site. It is a composite image created by stitching together overlapping digital images taken with the drone. Orthomosaic maps are most useful when surveying large areas, as they allow the surveyor to visualize the entire area at one time.
2. Digital Elevation Models (DEMs)
Overview of Drone Mapping
Drone mapping or aerial surveying in construction enables the delivery of maps as the end deliverables. Two of the most commonly used methods for drone mapping are photogrammetry and LiDAR. Each method produces different mapping outputs, with specialized data processing software required for analysis. This article will discuss the types of maps typically generated from drone surveys or mapping.
Understanding Photogrammetry
Photogrammetry is the process of using photographs to create 3D models, measurements, and maps. A drone is used to take overlapping photos from a variety of angles, which are then processed with specialized software such as Pix4D or Agisoft Photoscan. This software will be used to generate 3D models, orthomosaics, digital surface models, and point clouds.
Exploring LiDAR
LiDAR is a remote sensing technology that uses laser pulses to generate 3D maps. It is an incredibly fast and accurate method of mapping large areas, and produces incredibly detailed maps of the surveyed area. LiDAR data can be used to generate digital elevation models, 3D point clouds, and even 3D models of the surveyed area.
Generating Orthomosaics
An Orthomosaic map or ortho-map is a top-down map of a survey site. It is a composite image obtained by the camera by viewing straight down to a survey site or asset. Digital images are taken using drones and stitched together to create a 2D orthomosaic map. This map is developed when the area to be surveyed is large.
Understanding Drone Mapping
Drone mapping or aerial surveying in construction enables the delivery of maps as the end deliverables. Two of the most commonly used methods for drone mapping are photogrammetry and LiDAR. This article will provide an overview of these methods and the types of maps typically generated from a drone survey.
Exploring Photogrammetry
Photogrammetry is the process of using photographs to create 3D models, measurements, and maps. A drone is used to take overlapping photos from a variety of angles, which are then fed into specialized software such as Pix4D or Agisoft Photoscan. This software will be used to generate 3D models, orthomosaics, digital surface models, and point clouds.
Investigating LiDAR
LiDAR is a remote sensing technology that uses laser pulses to generate 3D maps. This method is incredibly fast and accurate, producing incredibly detailed maps of the surveyed area. LiDAR data can be used to generate digital elevation models, 3D point clouds, and even 3D models of the surveyed area.
Generating Orthomosaics
An Orthomosaic map or ortho-map is a top-down map of a survey site. It is a composite image obtained by the camera by viewing straight down to a survey site or asset. Digital images
3. Digital Surface Model (DSM) and Digital Terrain Model (DTM)
Overview of Drone Mapping
Drone mapping or aerial surveying in construction provides the end deliverables in the form of maps. The two common types of drone mapping methods are photogrammetry and LiDAR. Both the methods give different mapping outputs and require specific data processing software to study the data. This article discusses the common maps delivered after a drone survey or mapping process.
Understanding Photogrammetry
Photogrammetry is a method of mapping using photographs taken from a drone. It allows for 3D models to be created from overlapping images taken from different angles. These images are then analyzed using specialized software such as Pix4D or Agisoft Photoscan to create 3D models with accurate measurements. Photogrammetry can be used to create orthomosaics, digital surface models, and point clouds.
Exploring LiDAR
LiDAR is a remote sensing technology that uses laser pulses to generate 3D maps. LiDAR is a fast and accurate method of mapping large areas, and produces incredibly detailed maps of the surveyed area. LiDAR data can be used to generate digital elevation models, 3D point clouds, and even 3D models of the surveyed area.
Generating Orthomosaics
An Orthomosaic map or ortho-map is a top-down map of a survey site. It is a composite image obtained by the camera by viewing straight down to a survey site or asset. Digital images are taken using drones and stitched together to create a 2D orthomosaic map. This map is developed when the area to be surveyed is large.
DSM shows the structures on the surface, i.e., the top of the buildings and the trees.
4. Contour Line Maps
What is a Contour Map?
A contour map is a two-dimensional representation of a terrain’s elevation, consisting of lines that join equal elevation points. These lines are called contour lines and provide a visual representation of the peaks and valleys of a terrain, as well as the steepness of its slopes.
How to Create a Contour Map?
Creating a contour map requires a digital terrain model (DTM) or digital surface model (DSM) with custom contour intervals. By utilizing a drone to capture the area of interest, these models can be used to create an accurate picture of the terrain’s surface, giving an in-depth understanding of the topography.
5. 3D Point Clouds
What is a 3D Point Cloud?
A 3D point cloud is a collection of thousands of points with geospatial (x,y,z) and color information. It is generated from drone images, with each point being a geometric coordinate. When more coordinates are added, the point cloud becomes denser, providing a 3D model of the terrain.
How to Create a Contour Map from a 3D Point Cloud?
A Digital Terrain Model (DTM) or Digital Surface Model (DSM) with custom contour intervals can be used to create a contour line map from a 3D point cloud. This map provides a better understanding of the terrain’s surface, giving an accurate representation of the elevation, peaks and valleys, and slopes.
Image Credits: HEXAGON
What is the Benefit of a 3D Point Cloud?
A 3D point cloud provides a realistic representation of a terrain. It is accurate, allowing for easy measurement of distance, area, and volume.
How to Create a Contour Map from a 3D Point Cloud?
A Digital Terrain Model (DTM) or Digital Surface Model (DSM) can be created from a 3D point cloud. By adjusting the contour intervals, a contour map can be generated. This gives a detailed view of the terrain, providing a better understanding of its peaks and valleys as well as the steepness of its slopes.
Image Credits: Heliguy
FAQs
What is the DEM model in surveying?.
What is a Digital Elevation Model (DEM)?
A Digital Elevation Model (DEM) is a visual representation of elevation data for all the points captured by a drone. It is a raster image, with colors used to indicate the elevation difference.
How to Create a Contour Map from a Digital Elevation Model (DEM)?
A contour map can be generated from a Digital Elevation Model (DEM). By adjusting the contour intervals, the DEM can be converted into a two-dimensional map consisting of lines that join equal elevation points. This provides a better idea of the surface of the area, revealing peaks and valleys as well as the steepness of the slopes.
What is the difference between DSM and DTM models in surveying?
What is the Difference Between a Digital Terrain Model (DTM) and a Digital Surface Model (DSM)?
A Digital Terrain Model (DTM) is a representation of the bare-earth surface, featuring only the terrain and ground. On the other hand, a Digital Surface Model (DSM) includes all the points acquired and represents man-made and natural features on the earth’s surface.
How to Create a Contour Map from a Digital Terrain Model (DTM) or Digital Surface Model (DSM)?
A contour map can be created from a Digital Terrain Model (DTM) or Digital Surface Model (DSM) by adjusting the contour intervals. This provides a detailed view of the terrain, giving a better understanding of its peaks and valleys as well as the steepness of its slopes.
What are 3D point clouds in drone surveying?
What is a 3D Point Cloud?
A 3D point cloud is a collection of thousands of points with geospatial (x,y,z) and color information. It is generated from drone images, with each point being a geometric coordinate. When more coordinates are added, the point cloud becomes denser, providing a 3D model of the terrain.
How to Create a Contour Map from a 3D Point Cloud?
A custom contour interval can be used with a Digital Terrain Model (DTM) or Digital Surface Model (DSM) to create a contour line map. This gives a more detailed view of the surface of the area, providing a better understanding of its peaks and valleys as well as the steepness of its slopes.