Photogrammetry Applications in Aerial Photography

PhotoModeler Technologies’ photogrammetry software obviously has a wide variety of real-world applications, not the least of which is in aerial photography as performed by drones and other kinds of UAVs (unmanned aerial vehicles).

UAVs have become more readily accessible both to individuals and organizations over time. Today, they are highly popular among individuals looking to capture some stunning video footage from the skies, but in this post, we will focus on industries that rely on aerial photography to get their work done. Then we will discuss how our photogrammetry software can be applied to those industries by taking measurements from the photos and creating 3D models based on those images.

The ability to chart a wide area of land that has been photographed from the sky and then create a scaled computer model of that area is what makes PhotoModeler software so valuable to our clients. Photographs from several hundred feet in the air can show people only so much. They offer clear views of different areas of the ground, no doubt, but they are disjointed pieces of a larger whole that many industries need to see at a glance.

PhotoModeler Technologies’ photogrammetry software makes all of this possible. We hope this resource educates you a little further in the kinds of industries that use aerial photography and how our photogrammetry software can improve those enterprises substantially.

Aerial Photography in Industry

People often employ drones and other UAVs to capture photography from the air, compared to other techniques,  because a) it can be more efficient for larger areas, and b) it would be dangerous or impossible for them to attempt it directly. This could be due to the region being impassable by ground or being a restricted area such as a highway or in volatile geopolitical situations. Whatever the case, UAV-executed aerial photography has become a major boon to people and groups in the last decade.

Let’s look at some of the organizations and industries that depend heavily on UAVs taking aerial photography.

Land Surveying

As mentioned, sometimes it is difficult to survey a large area of land on foot. This is where UAVs come in. They make the entire process of surveying land more affordable and efficient. UAVs can fly either several hundred feet in the air or close to the ground, depending on the topography of the land being surveyed. Acquiring perspectives from high up is beneficial since the imagery returned will display larger parts of the land all at once. However, despite the efficiency of drones, surveyors must always allow for areas that present obstacles even to UAVs. These obstacles could be anything from trees to dense brush. In these cases, the vehicles can fly closer to the ground, or the camera pointed at an angle to see what additional information can be gotten from the new perspective. UAV photogrammetry in land surveying has met a strong need in construction planning and management.

Disaster Relief

Just as UAVs make it safer and more convenient for surveyors to do their jobs, so, too, can they assist emergency responders in providing disaster relief. During widespread catastrophes such as earthquakes, wildfires, and floods, it can be hazardous for people to assess property damage and humanitarian need. In those situations, there is almost no better way to mitigate the risk to first responders than by sending UAVs into the skies above a disaster area to photograph the situation on the ground. The photos and videos taken in the air can be used to plan relief efforts such as putting out parts of a wildfire or rescuing stranded people.

Cartography

It stands to reason that modern-day cartography would also benefit hugely from UAV-executed aerial photography, and this is certainly the case. Typically, aerial photography for cartography has been done with full-sized manned aircraft or satellites rather than with drones or other UAVs. This is primarily because the areas photographed for new maps are larger and require such hardware. However, in some instances where smaller new areas are being mapped, drones can definitely be used.

In any case, experienced cartographers and planners know how to interpret what they see when drawing new lines for property and other boundaries. In this same vein, historians and geologists have used UAV-based aerial photography when investigating archeological sites that might be otherwise inaccessible by ground.

Public Safety

Another practical use of UAV photography–and, consequently, photogrammetry–is in public safety, primarily in accident scene reconstruction. Of course, up-close ground photos will always be required, but drones that can fly right over the scene of a car crash can get bird’s-eye-views of the whole situation. Our PhotoModeler product, which has been used for accident scene reconstruction since the early 1990s, can then turn all the photography into 3D models or 2D diagrams that investigators can examine from the convenience of their computers, or be used in court.

How Aerial Photogrammetry Applies

Aerial photogrammetry consists of using the imagery gathered in the air by UAVs to create computer-generated 2D and 3D models. These models are topographical in nature, meaning they represent the dimensions and physical features of the area of land, and in stunning accuracy. These models can be rotated and zoomed. Because they are created entirely from images of the real locations as captured by a UAV, they will show every last photographic detail that exists in those photos.

Having a resource such as photogrammetry software can be vital to all the industries mentioned here and a plethora of others. But exactly how does it work? How can PhotoModeler Technologies’ photogrammetry software really assist a surveyor or forensic engineer? To understand any of this, we first need to know how photogrammetry programs use aerial photographs to generate their models.

Photo Triangulation

Let’s start with a drone-borne camera taking a picture. When you view that picture, what you are actually seeing is a large number of points of light that all exist together to form an image your eyes can detect. Each point of light is created by a ray that extends from the object being photographed to the camera, through the lens, and to the imaging surface (film or chip). When photogrammetry software begins creating models from such images, it also requires information such as the position and angles of the camera, as well as the focal length, pixel size, and lens distortion.

When using a drone to take aerial pictures for photogrammetric purposes, it is important to ensure that multiple shots are taken of the same areas. This is because our software cannot triangulate the positions of objects in photographs without comparing them to their positions in other photographs. Finding the same 3D points in multiple photos is called point matching while triangulating involves using several photographs to “solve” those points in 3D space. This point matching can be done either manually or automatically.

To obtain all the necessary shots of a large area of land, a drone might have to make several passes in the air (called flight lines), and perhaps fly close to the ground to acquire more detail. Whatever the method, in the end, a collection of overlapping shots of the same region of ground must be acquired for the photogrammetry software to do its job correctly. Once our PhotoModeler product has access to all your photos, it will produce a 3D map containing scaled lines and geographical features, or orthographic photo-mosaics (a perfect photo that covers a large area).

Some of the interesting outputs are 2D scaled drawings, accurate 3D terrain models, 3D models with mapped photographic textures, contour lines, and ortho-photo-mosaics.

Advantages of Aerial Photogrammetry

Given the amazing power of the PhotoModeler photogrammetry product, it’s no wonder so many industries rely on PhotoModeler Technologies to complete their work. 

Photogrammetry uses computer science to help people accomplish great things, and we are happy that so many industries trust us to keep getting the job done.

For questions or concerns about our product, please contact our corporate office at  sales@photomodeler.com.

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