FAQ on photogrammetry
What is photogrammetry? And how does it work?
For decades, we have been using photogrammetry to observe faraway objects in space. However, recent advancements in technology have become a significant part of large-scale industries like construction, architecture, medicine, geology, and much more. It has brought many positive changes in our lives and made professions easier.
What is Photogrammetry?
Photogrammetry is a scientific process that records, interprets, and measures photographs and electromagnetic radiations to obtain credible information about the environment and objects shown in the photographic images.
As a result of the input (the photographs), we get output 3D models, maps, or diagrams. We can utilize the output to create real-world scenes.
How does Photogrammetry work?
How does software convert a photograph into a 2D or 3D model? It is one of the frequently asked questions related to Photogrammetry, and here’s the answer:
A photogrammetry software obtains information like height, distance, areas, and elevation from 2D photographs. The software further analyzes different points on the overlapping photos at varying angles. Here, the software creates a collection of data points that defines the object’s shape. In this way, the point clouds create a 3D model of the input photographs.
Types
There are two types of photogrammetry:
1. Aerial Photogrammetry:
Aerial photogrammetry is the process of taking pictures from a camera directed downwards while mounted on an airplane. And after that, the captured photographs are processed in a stereo plotter which finds elevations by calculations.
2. Terrestrial Photogrammetry:
Terrestrial photogrammetry is the process of taking pictures from a camera that is fixed on the ground and is parallel to the Earth. Instruments called theodolites are often used in terrestrial photogrammetry. Terrestrial photogrammetry needs fewer resources but takes much time to cover a massive portion of land.
A review of three software
After capturing it, one needs digital software to generate 2D or 3D models of a photograph. Here’s a comparison between three photogrammetry software that will help you understand what are the differences you can find on the market. There are many software and those are just one sample.
Disclaimer
We also use Autodesk ReCap, RealityCapture and Pix4Dmapper intensively as well as other small shop apps, each having their own strength of interest and for which we did not discuss here in depth.
Most common questions on photogrammetry
1. What is Photogrammetry?
Photogrammetry is the process of deriving 3D spatial information from 2D images. It involves the use of photography, remote sensing and computer processing to produce accurate and detailed maps, models and measurements of the surface of the earth and other objects.
2. What is the history of Photogrammetry?
Photogrammetry has a long history, dating back to the early days of photography. The first known use of photogrammetry was in the late 1800s for topographic mapping, and the technology has since evolved to encompass a wide range of applications.
3. How does Photogrammetry work?
Photogrammetry works by taking multiple photographs of a scene or object from different angles, and then using software to process these images and extract 3D information. This process involves identifying common points in the images, measuring their positions and using this information to calculate the shape and location of objects in the scene.
4. What are the key components of a Photogrammetry system?
A photogrammetry system typically consists of a camera, a tripod, software for image processing and analysis, and sometimes additional hardware such as a GPS receiver or laser rangefinder.
5. What are the different types of Photogrammetry?
There are several different types of photogrammetry, including close-range photogrammetry, aerial photogrammetry, satellite photogrammetry, and oblique photogrammetry.
6. What is Close-Range Photogrammetry?
Close-range photogrammetry is the process of using photogrammetry to produce detailed maps, models and measurements of objects or scenes that are within a few meters of the camera.
7. What is Aerial Photogrammetry?
Aerial photogrammetry is the process of using photogrammetry to produce maps, models and measurements of the earth’s surface from an aircraft, or a city in 3D from drone as we will expand the use 3D cities with Virtualia Shop.
8. What is Satellite Photogrammetry?
Satellite photogrammetry is the process of using photogrammetry to produce maps, models and measurements of the earth’s surface from satellite imagery.
9. What is Oblique Photogrammetry?
Oblique photogrammetry is a type of photogrammetry that involves taking images of an object or scene from an angle, rather than directly overhead.
10. What are the benefits of Photogrammetry?
Photogrammetry offers several benefits, including high accuracy, low cost, the ability to produce detailed maps and models, and the ability to collect data in difficult-to-reach locations.
11. What are the limitations of Photogrammetry?
Some of the limitations of photogrammetry include the need for a clear line of sight between the camera and the objects being captured, and the difficulty of capturing objects that are partially obscured or occluded.
12. What are the applications of Photogrammetry?
Photogrammetry has a wide range of applications, including mapping, surveying, engineering, archaeology, and cultural heritage preservation.
13. What is the role of software in Photogrammetry?
Software plays a critical role in photogrammetry by processing the images captured by the camera and extracting the 3D information needed to produce maps, models and measurements.
14. What are the key features of Photogrammetry software?
Photogrammetry software typically includes features such as image calibration, point cloud creation, 3D modeling, and the ability to export data to a variety of formats.
15. What is Image Calibration in Photogrammetry?
Image calibration is the process of adjusting the images captured by the camera so that they are aligned with each other and with the coordinate system used for mapping.
16. What is Point Cloud in Photogrammetry?
Point cloud is a data structure used in photogrammetry to represent a 3D model of a scene or object. It is created by extracting features from images and using them to calculate the position of each feature in 3D space.
17. What is 3D modeling in Photogrammetry?
3D modeling in photogrammetry involves using the information from point clouds to create a 3D representation of a scene or object. This can be used for a variety of purposes, including visualization, analysis and simulation.
18. What is the difference between Photogrammetry and LiDAR?
Photogrammetry and LiDAR (Light Detection and Ranging) are both techniques used to produce 3D maps and models. Photogrammetry uses photographs to produce 3D information, while LiDAR uses laser pulses to scan the environment and create a point cloud. LiDAR is generally more accurate than photogrammetry, but it is also more expensive and requires specialized hardware. It is however less efficient for transparent and reflective materials.
19. What is Multi-View Stereo in Photogrammetry?
Multi-View Stereo (MVS) is a technique used in photogrammetry to produce 3D models from multiple images taken from different angles. MVS involves processing the images to identify common features and use them to calculate the shape and location of objects in the scene.
20. What is Structure from Motion in Photogrammetry?
Structure from Motion (SfM) is a technique used in photogrammetry to create 3D models from a series of images captured by a moving camera. SfM works by tracking the movement of features in the images and using this information to calculate the position and orientation of the camera and objects in the scene.
Summary
Photogrammetry is the process of extracting 3D information from 2D images using computer processing, remote sensing and photography. It is used for mapping, surveying, engineering, cultural heritage preservation and other applications, and has many benefits including high accuracy and low cost.
References
https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/photogrammetry
https://www.takeoffpros.com/2020/06/16/what-is-photogrammetry/
https://www.sculpteo.com/en/3d-learning-hub/3d-printing-software/photogrammetry-software/
