The word “photogrammetry” is derived from three Greek words; light (φως), drawn line (γραμμή) and to measure (μέτρο):
φως + γραμμή + μέτρο
Thus we describes how photogrammetry works at its core – light travelling in a straight line from a subject to a fixed point can be measured.
Indeed, the technique has a long history. As early as 1851 French military engineer Aimé Laussedat had begun to experiment with images for topographical recording using a camera lucida to project subjects onto a drawing surface.
The method is as much science as art, recognised by the American Society for Photogrammetry and Remote Sensing (ASPRS) in their definition of what is photogrammetry:
Photogrammetry and Remote Sensing are the art, science and technology of obtaining reliable information about physical objects and the environment, through a process of recording, measuring and interpreting imagery and digital representations of energy patterns derived from non-contact sensor systems.
Today photogrammetry has a wide range of applications. Its non-intrusive, non-contact methods can be extremely beneficial with delicate subjects such as the human form or within archeology. The ability to work through water has seen underwater photogrammetry prove exceptionally useful at recording otherwise impossible subjects. Surveyors can quickly derive accurate measurements, calculate area and volume of stock piles, and record progress on infrastructure projects.
Yet none of this would be possible without two concurrent and recent inventions; digital imaging and cameras, and powerful yet low cost personal computers.
How Does Photogrammetry Work?
At its core, photogrammetry requires a set of overlapping images aligned by identified points. Additionally, photogrammetry software locates tens of thousands of these points and matches them to identify common features in neighboring images.
From the aligned images, you can estimate the distance from the camera sensor. Furthermore, you can extract a digital 3D surface that captures the shape and form of the subject.
Improved Accuracy and Measuring
The digital photogrammetry model can have supplementary data added that considerably improves its value. You can apply real-world distance measurements to constrain the model. Additionally, geospatial data like latitude, longitude, and altitude can position the model accurately within the real world.
From this data, you can reliably take any arbitrary measurement, whether it’s distance, area, or volume. Moreover, this capability unlocks the potential to ask more questions and derive accurate answers.
From the aligned cameras, you can extract more than just a 3D mesh. Additionally, you can create a Digital Elevation Model (DEM) or a Digital Terrain Model (DTM).
The source images themselves may be rectified and merged to form a single massive detail site plan rendered in true colour. Typically called an orthomosaic, experts produce these site plans at a resolution of 1mm per pixel. This fine level of detail results in file sizes often measured in gigabytes.
Merging photogrammetry with laser scan data combines the texture-rich detail of photographs to the precise data derived from the laser.
What Photogrammetry Cannot Do
Photogrammetry has its limits. Untreated polished, transparent or reflective surfaces cause significant errors, rendering subjects like cars, glass fronted buildings, ceramics or water as difficult-to-impossible to capture.
There are some advanced techniques. Notably, as using cross polarising light filters to capture the source images, or treating the surfaces with an anti-reflection coating, that can help photogrammetry succeed.
Furthermore, our courses help the beginner understand the power and limits of photogrammetry. For the advanced user we go deep into how accuracy and quality can be checked and consistently applied no matter what equipment used or type of subject being scanned.
How Can You Learn?
If you’re wondering, “what is photogrammetry?” it’s a powerful technique for capturing precise spatial data from images, and mastering it can transform your approach to 3D modeling and analysis. At AccuPixel, we offer a range of comprehensive photogrammetry courses. Our courses are designed to equip you with the skills needed to excel in this field. Our 3DF Zephyr Advanced Course dives deep into the intricacies of 3D modeling using Zephyr. This course is ideal for those looking to enhance their expertise with advanced features and techniques. For those just starting, our 3DF Zephyr Foundation Course provides a solid grounding in the basics of photogrammetry with Zephyr. Moreover, this course ensures you build a strong foundation.
Additionally, our Agisoft Viewer course offers essential training on using Agisoft’s viewer tools. In fact, these tools are crucial for effectively visualizing and analyzing your photogrammetric data. Similarly, If your focus is on forensic or surveying applications, our Metashape Professional Edition for Forensics & Surveying Course is perfect for you. The course delivers specialized knowledge on utilizing Metashape’s advanced capabilities for these critical fields. For those new to Metashape, our Metashape Foundation Course for Forensics & Surveying introduces the fundamental principles and practices necessary to get started with Metashape in forensic and surveying contexts.
Final Words on “What is Photogrammetry?”
In conclusion, each course is tailored to address different aspects of photogrammetry. From foundational concepts to advanced techniques, ensuring you can find the right training to match your needs. Whether you’re a beginner or a seasoned professional, our courses will help you understand exactly what is photogrammetry. Our courses show you how to apply photogrammetry effectively in your projects. So, check out our offerings today and take the next step in your photogrammetry journey with AccuPixel. Our courses offer valuable training and our company includes experts who are available to assist and answer your questions. Additionally, AccuPixel offers consulting services to ensure your project is successful.
Please follow us on LinkedIn and Facebook to hear updates about AccuPixel’s ongoing work and updates. We thank you for taking the time to learn more about what is photogrammetry and how we can use it. If you have any questions, please feel free to contact us at any point! To sum up, we believe photogrammetry is a useful tool with a plethora of applications.
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