Unlocking Aerial Survey Potential with Oblique Photogrammetry

Oblique Photogrammetry
June 20, 2023
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By Ella McConnell, Marketing Specialist

As many of you know, I’m still learning about the geospatial industry, and I’m always trying to deepen my understanding of the products that we buy and sell through AERIALSURVEY.com. I’ve had many conversations with Pat McConnell, President of ClearSkies Geomatics, Inc over the past year.

One topic we discussed recently was about oblique photogrammetry. How are oblique sensors used differently from those that do nadir imaging, and why?

We’ve recently sold two Vexcel Ultracam Eagle systems, and that led to a discussion about how the Eagle differs from the Ultracam Osprey Mark 3 system we have listed on our website. I learned a lot and thought the topic was perfect to share as a blog article.  

“Let's start with the basics - how would you explain the difference between nadir and oblique photogrammetry?”

“Nadir photogrammetry is when the image is captured with the camera pointed vertically downwards towards the Earth's surface.”

nadir image example
Nadir Image Example

Oblique photogrammetry is the process of capturing multiple aerial images of a single location from different angles or perspectives.”

Oblique photogrammetry example
Sample data from Vexcel Osprey Mark 3

“What are some advantages of nadir and oblique imagery?”

“The main advantage of nadir photogrammetry is that it provides a comprehensive detailed view of the Earth's surface. By capturing images from directly above, it eliminates distortions.

Oblique photogrammetry provides detailed visual information about objects and structures from different viewpoints. These images are taken by both nadir and oblique angled cameras. By combining these images with photogrammetry algorithms, 3D models of the environment can be created.”

“What companies/industries are the biggest users of oblique cameras, and why?”

“Off the top of my head, there are three industries I can think of, that are big users of oblique sensors. Oblique photogrammetry sensors are great for corridor mapping a.k.a., linear mapping. For example, power corridors and train track mapping. It is also often used by insurers and reinsurers and by the real estate industry because you can see building from different angles (roof, sides of buildings).  Civil engineers also have use for this type of photogrammetry so they can see the rates of progress in their construction projects.”

“What sensor do you recommend for a company looking to branch into oblique imagery?

“For manned aerial surveys, the Vexcel Osprey Mark 3 is a high-resolution large format oblique sensor that revolutionized the market for oblique photogrammetry. It’s a great starter oblique camera to get in the market, and a very economical investment.

“Can you be more specific about the benefits of oblique photogrammetry with the Vexcel Osprey Mark 3?”

“The Vexcel Osprey Mark 3 has advanced optics that capture high-resolution oblique imagery with excellent clarity and precision. The sensor's oblique cameras have an ideal view tilt angle of 45 degrees. This sensor has full swath width of the nadir cone in conjunction with the perfectly configured oblique image overlap. This allows for simultaneous nadir and oblique image capture, maximizing efficiency and reducing acquisition time.”

The latest version is the Vexcel Osprey Mark 4.1. Can you speak to what a company should consider when deciding whether a Mark 3 or Mark 4.1 is the best fit for their projects?"

“You have to make sure you have the right sensor for your project needs and platform. The Osprey Mark 4.1 has a similar nadir swath as an Eagle Mark 1 plus the oblique camera for survey-grade imagery. Meaning the sensor can fly higher and faster. In a platform like a Piper Navajo, the Osprey Mark 4.1 can cover more mapping area per flight, which makes it really efficient for wide-area oblique photogrammetry.

Vexcel UltraCam Mark 3 Premium

On the other hand, in some areas of the world with lots of cloud cover, the Osprey 4.1 would be overkill. You wouldn't be able to take advantage of its efficiency feature’s because you have to fly lower and slower.

There’s also a significant cost advantage to purchasing a pre-owned system. It’s a matter of economics. If you have the budget for new sensor, and you have the proper platform to fly it, the Osprey Mark 4.1 is an excellent, bleeding-edge photogrammetric sensor. If a pre-owned Osprey Mark 3 will fit your climate, your project's needs, and you’re flying something like a Cessna 206 which lets you fly slower and lower, you can’t beat the investment.”

“This has been very educational. Thank you for your time.”


After speaking with Pat, I was able to learn a lot about oblique photogrammetry sensors, what industries uses them, why they use them, and how a pre-owned Vexcel Osprey Mark 3 is a great option for getting into the market of oblique photogrammetry.

The ability to capture high-resolution, multi-directional imagery opens up new possibilities for professionals across various industries.  Embracing innovations and changes in geospatial technology is crucial for companies seeking to stay at the forefront of their industries and leverage the full potential of aerial data acquisition. If you are interested in learning more about the Vexcel Osprey Mark 3, check out our listing here.

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