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Photogrammetry

What is Photogrammetry??

The word Photogrammetry is derived from the parts

"photo" meaning "light";

"gram," meaning "drawing";

and "metry," meaning "measurement."

 

Photogrammetry is the science of making reliable measurements by the use of photographs and especially aerial photographs.

Photogrammetry has been around for centuries. In 1492 Leonardo da Vinci began working with perspectives and central projections with his invention of the Magic Lantern. Although there is no evidence of an actual working model, principles of perspective and projective geometry formed the basis from which photogrammetric theory is developed. Many believe that the Magic Lantern could actually date back to the early Greeks. In 1883 R. Sturms and Guido Hauck developed the mathematical principles of a perspective image using space resection to find a point in space from which a picture is made. Over the next couple of centuries many advancements were made in this science. One of the pioneers of modern photogrammetry was Gilbert Louis Hobrough. Hobrough developed an airborne profile recorder that used radar to measure the range from an aircraft to the ground with about one foot accuracy. Hobrough also developed a reference barometer with the same comparable accuracy. In 1967 he developed the Gestalt Photo Mapper. This automated orthographic system utilized stereo imagery. It consisted of a printer, a scanner, correlator and computer system, and an input/output device. This would lead to him playing a vital role in the development of digital photogrammetry that we know today.

How exactly does photogrammetry work?

Photogrammetry involves taking overlapping photographs and measuring one or more points in the photos taken from different angles to create a 3D model. Using a calibrated camera with known focal length, the angles between light rays from various points in a photo can be determined. Using 3D coordinates from any given coordinate system the perspective center and orientation of the image can be determined. Using these overlapping images the 3D vectors can be intersected to determine the 3D position of that point in the photos.

 

Easy right? Not so fast!

 

There are many factors to take into account when providing aerial photographs for 3D modeling. Producing high quality 3D models and point clouds that can be used for measurements isn't as easy as taking a bunch of pictures and importing them into some software. Weather, time of day, and atmosphere are just a few of the many factors to take into account when conducting photogrammetry missions. Then you need to now how to handle the millions of data points to provide clear accurate results. 

From hot air balloons to manned fixed wing aircraft to modern day sUAV, photogrammetry has proven to be an accurate and effective method to gathering quality data. At Flightfield Drone Services, LLC we have conducted numorous photogrammetry missions over the past several years. Before starting Flightfield Drone Services, LLC our sUAS Pilot was a Lead Surveyor at a local engineering firm. During that time, he used survey grade GPS and his own sUAS, to conduct flights for road corridors, water line corridors, landfills, lagoons, stockpiles, mapping for legal surveys, orthomosaics, and more. He would then perform all of the post-processing to produce the deliverables required by the various clients. At FDS we have the technology and the knowledge to provide you with the best aerial services around. With a mobile command center and onsite charging we can cover very large areas without delay. Our photogrammetry services are not just for engineers and architects. They can be used by farmers, ranchers, municipalities, insurance companies, real estate, and many other professions.

 

Are you wondering if photogrammetry can help you? Click the tab below to contact us with any questions and “See Your World Differently” today!

Below are examples of 3D point clouds created from aerial photos. Incorporate surveyed ground control points into the aerial photos and produce even higher accuracies within the point cloud. 

This point cloud of a school addition project contains 23,864,818 points and took 17 minutes to capture

This point cloud, used to calculate a stock pile volume contains 14,369,636 points and took 12 minutes to capture. Not only did the owner get the volumes for the pile he wanted. He can also request volumes of additional piles that appear in this point cloud. Thus saving time and money by not needing additional flights for additional piles. 

This point cloud of a public swimming pool project contains 17,679,479 points and took 15 minutes to capture. In this video clip you can see the camera locations with thumbnails representing the drone's AGL (above ground level) and the orientation of the camera angle. 

When it comes to stock pile volumes Flightfield Drone Services, LLC is your quickest, most accurate choice. Being able to capture 10 acres in 10-15 minutes, then provide volumes before the end of the day benefits all parties. For large sites we have the capability of onsite charging to keep us going until the job is done. 

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Below are some examples of orthomosaic photos. Having FDS create these photos enables you to see large areas in a single photo. Being able to zoom in and keep the detail eliminates referencing outdated satellite imagery on  Google Earth or other map platforms. 

Capturing data to create orthomosaic photos at different times of the construction process can help with keeping owners, and investors up to date on the construction progress

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Below is an example of the zoom capabilities with orthomosaic photos. On the left is the entire photo, and on the right is the clarity when zoomed in. You can click on either photo to enlarge it in a new window and see even more detail.

Photostitched drone photography example
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If you have questions on how FDS can help you with our photogrammetry services. Click on the tab below and start to "See Your World Differently."