3D laser scanning and photogrammetry are advanced techniques used for capturing and creating three-dimensional representations of physical objects or environments. They have changed the way we have documented and interacted with the physical world. The tools help to bridge the gap between the real and digital worlds. Let’s analyze the differences between the two techniques.
A laser scan captures spatial data with accuracy. The technique uses laser beams for measuring distances and creating detailed point clouds. The method works perfectly for complex structures in engineering and construction. On the other hand, photogrammetry creates 3D models through overlapping photographs.
This technique is cost-effective and especially suitable for large-scale mapping and aerial surveys. This plays a significant role in agriculture, archaeology, and environmental monitoring.
Laser scanning and its types
3D scan Uses active range Sensing Laser beams actively probe the object, generating millions of data points. By creating point clouds, each point represents distance and location, creating a high-resolution 3D representation. The micrometer-level details formed through lasers are ideal for complex shapes and close-range applications.
Different types of 3D scanners are used in construction
- Terrestrial Scanners: They manage large indoor and outdoor spaces, capturing accurate data through long-range capabilities.
- Airborne laser scanners: These help to scan vast areas quickly and efficiently and are perfect for mapping cities, forests, and landscapes.
- Mobile Laser Scanners: Mounted on vehicles or even backpacks, they navigate dynamic environments such as roads and tunnels, providing real-time 3D scans.
- Single-Point Long-Range Scanners: These scanners pinpoint distant objects with accuracy and are ideal for measuring bridges and wind turbines.
Software facilitating the accuracy of 3D laser scanning: ReCap Pro (Autodesk) is the industry standard for point cloud processing, registration, and editing, helping professionals in the fields of engineering, construction, and survey.
Geomagic (3D Systems) is another software application that offers advanced point cloud filtering and reverse engineering capabilities. This software application is popular for manufacturing and design applications.
Leica Cyclone is one more piece of software for managing and visualizing large point cloud datasets. This is often used in mining, archaeology, and infrastructure management.
Software Integrated with Point Cloud for 3D Modeling and Meshing: Trimble SketchUp Pro is a popular 3D modeling software with integrated point cloud processing tools. This is user-friendly for creating detailed models from scan data.
MeshLab is another open-source software for manipulating, editing, and analyzing point clouds, offering advanced tools for researchers and developers. 3DVinci software creates high-quality meshes and textures from point cloud data. This is ideal for architectural visualization and virtual reality.
Photogrammetry and its types
Passive acquisition of images takes place in photogrammetry by overlapping photographs and capturing geometric information. This is fast, versatile, affordable, and works in diverse lighting conditions. However, it has less accuracy than laser scanning and struggles with small details and featureless surfaces.
Different types of Photogrammetry techniques
- Metric Photogrammetry: This approach uses standard cameras and advanced software to achieve accurate measurements for survey and engineering.
- Structure from Motion: This technique utilizes consumer-grade cameras and user-friendly software to create 3D models from overlapping photos.
- Multi-Image Matching: This method depends on specialized software to match aerial or close-range images, producing 3D models of large areas.
Photogrammetry Software Application for Motion and Multi-Image Matchin
- Agisoft Metashape offers reconstruction, editing, and analysis.
- Pix4D is another user-friendly software for 3D modeling and ‘orthomosaics’ from drones and aerial images. This is popular for surveying, agriculture, and environmental monitoring.
- Meshroom (OpenDroneMap) is one more open-source piece of software for automatic 3D model reconstruction from photogrammetry, offering a budget-friendly solution.
Software for Metric Photogrammetry
- Bentley MicroStation is a professional software application for accurate 3D modeling and measurement.
- Leica Zeno Photogrammetry software helps create accurate 3D models and maps from aerial and terrestrial images for construction and infrastructure maintenance.
- ContextCapture (Bentley) software is suitable for large photogrammetry projects, providing automated reconstruction and edits for detailed 3D models of cities, landscapes, and complex structures.
Comparing laser scanning and photogrammetry
Knowing the fundamentals of laser scanning and photogrammetry, let us compare both technologies based on various critical metrics of reality capture and project documentation
Speed and Efficiency
3D Laser Scanning has methodical precision. The laser scans every inch cautiously, building point cloud. This may not be the fastest approach for big areas, but the quality is worth the wait. On the other hand, Photogrammetry is swift and efficient. This technique captures tons of pictures in minutes with high-quality cameras, and by using the right software, the 3D model can be created in a flash. This makes it ideal for quick surveys, capturing dynamic environments, or situations where time is tight.
Environmental Considerations
Laser Scanning: Sensitive to the Elements: Laser scanning can easily be thrown off by distractions. Bright sunlight can confuse laser beams, bouncing them off shiny surfaces like mirrors. Obstacles can block line of sight, leaving blank spots in his point cloud masterpiece. It prefers controlled environments with gentle lighting and clear paths for its laser beams.
Photogrammetry: Lighting and Surface Dynamics: Photogrammetry can adjust to various lighting conditions. While good lighting and textured surfaces give it the clearest pictures, it can still work with shadows and flat surfaces. It can adjust settings to get the best shot, even in tricky conditions.
Equipment and Accessibility
A laser scanner is an expensive instrument that shoots laser beams and records reflections. It is a futuristic surveyor’s toolbox! This equipment limits scanning to professionals and specialized projects due to its high cost and technical complexity. Photogrammetry works with readily available tools. From Smartphone cameras to drones, it can readily adapt to various equipment. This makes it budget-friendly and accessible. Whether it’s a quick scan of living room or a vast landscape survey, Photogrammetry can work with what you have.
Diverse Applications of Laser Scanning & Photogrammetry
| 3D Laser Scanning | Photogrammetry |
| Laser scanning is a precision tool used in engineering, construction, and metrology for precise measurements, structural integrity, and precision in building complex prototypes, creating accurate as-built models, and standardizing instruments for high-precision inspection. | Photogrammetry is a versatile tool used in surveying, archaeology, and environmental monitoring, providing valuable insights into our environment and preserving historical treasures. It maps vast terrains, topologies, reconstructs ruins, and tracks forest cover and erosion patterns. |
Data Density Dynamics
A laser scanner generates millions of point clouds, each indicating a precise measurement, resulting in a super-dense point cloud data. This is particularly true for close-range scans, which capture every detail. This massive data set is ideal for deep analysis, reverse engineering, and accurate land mapping.
Photogrammetry is the process of converting photos into three-dimensional images. The density of data is determined by the quality and quantity of photographs.
High-quality photographs and overlapping perspectives result in a denser, more data, whereas fewer photos or lesser resolution yield a sparser data. While not as dense as laser scanning for close-range operations, photogrammetry successfully captures wide areas while balancing detail and processing time.
Photogrammetry: Variability in Point Cloud Density:
Photogrammetry uses photographs to paint 3D pictures. But the number of dots in point cloud depends on the tools. High-resolution photos and overlapping angles create a denser and detailed point cloud. With fewer photos or lower resolution, the dots become sparser, like a pointed landscape painting.
While not as dense as laser scanning in close-range scenarios, Photogrammetry can still capture large spaces effectively, balancing data density with processing time.
Benefits of using 3D Laser Scanning to BIM Services:
- Create as-built 3D BIM models for existing buildings & renovation.
- 3D models are updated as per the contractors, facility managers, or architect’s prerequisites in a simulated environment.
- Modeling using point cloud to BIM Services data helps the architecture to make decisions about wanted or unwanted components and structures of the building.
- Laser Scanning to BIM technology creates a clash simulation analysis for Architectural & MEP services at an initial phase of feasibility review while adding new services.
How to Know Which Is Best Laser Scanning vs. Photogrammetry?
| Feature | Laser Scanning | Photogrammetry |
| Accuracy | High, within ¼ inch for most scanners | Lower, especially over large spaces |
| Scale | Handles large areas well | Limited by camera lenses and clarity at distance |
| Cost | Expensive equipment, pricey upgrades | Affordable, works with standard cameras |
| Automation | Highly automated, low user error | More manual process, experience matters |
| Time on Site | Less time spent capturing data | More time spent taking photos and processing |
| Data Processing | Advanced software for point cloud extraction and meshing | Auto-extraction less developed, manual work needed |
| Visuals | Limited visual appeal, struggles with textures and reflections | Excellent for capturing textures and realistic appearances |
| Best for: | Precise measurements, detailed object scans, large-scale accuracy | Creating visually stunning models, mapping large spaces, budget-friendly projects |
Photogrammetry and 3D laser scanning are both good in their own right. Consider your budget, the size of the region, and the level of accuracy you require when selecting which is the best fit for your needs.
Photogrammetry is the way to go when you need to render a landscape as a 3D model for an archaeological survey or movie visuals, for example. Photogrammetry, as opposed to 3D scanning, will deliver better overall outcomes because capturing the reality of the scene is most crucial.
Photogrammetry with targets is the best, and possibly only, solution if you require very high precision of specific spots in your scene or on your object. Whereas, 3D scanning is well suited to dense cloud capture of smooth surfaces. 3D scanning is great for capturing big areas with a lot of information.
For specialized uses, you can combine the two. A forensics team may need to examine surveillance footage to figure out what happened in order to solve a case. A 3D model may be produced and critical evidence extracted from surveillance footage using 3D scanning and photogrammetry.
Should I Use Laser Scanning or Photogrammetry For 3d Documentation?
It’s difficult to picture a world without digital technology. However, most of the physical world, as you can see, was developed and built using traditional 2D plans and has yet to be preserved in a digital manner. This makes difficult to incorporate as-built designs into re-build or refurbishment projects for AEC professionals.
Now the question is which technology should we use? Laser Scanning Or, Photogrammetry? Let’s discuss broadly on the topic of Photogrammetry vs 3D Scanning
Traditional imaging techniques of Photogrammetry supports engineers to piece together images of as-built settings and include GPS data to build interactive 3D models.
However, while photogrammetry allows you to cover a broad area rapidly, it does so at a poor level of accuracy. 3D laser scanning, on the other hand, often collects data with a smaller footprint but with a better level of accuracy.
Laser scanners capture surface data using a laser beam focused at the surface, frequently with the help of drones or unmanned aerial vehicles (UAVs) (eliminating expensive LiDAR gathering methods), and then convert the data into a point cloud.
The point cloud data can then be entered into software like Autodesk ReCap, which quickly turns it into a 3D model or 2D drawing that can be used for future design. Autodesk ReCap turns aerial and object pictures to 3D models in addition to laser scans.
Further Reading
