How to Choose an Airborne Camera for Aerial Survey! (10-Step Checklist)

Selecting the right aerial camera for your business is a challenge today. The market is awash with promises and conflicting information from different companies, making it tough for customers to…
8 min read
806

Selecting the right aerial camera for your business is a challenge today. The market is awash with promises and conflicting information from different companies, making it tough for customers to make an informed choice. The 10-step checklist I’ll share with you has guided many geospatial professionals in finding the ideal aerial camera for their needs.
We’ll use our Vexcel Ultracam Merlin 4.1 aerial camera system as a reference.

Let’s get right into the checklist.
We first introduced this checklist in our UltraCam Merlin 4.1 webinar. It’s a tool designed to simplify and enhance comparison of different systems available in the market. You can also find the checklist on our website via this link: Vexcel_10-Point-Checklist.pdf (vexcel-imaging.com)

Image Sensors

Many current airborne camera systems on the market, including all Vexcel’s 4th generation UltraCam systems, use the same 150 MP CMOS sensor from Sony. This sensor has become the industry standard for high-resolution aerial imaging, so you won’t see much difference in this particular aspect across various aerial systems.

150 mp CMOS (Complementary Metal Oxide Semiconductor) sensor

System Approach Efficiency

When choosing an aerial camera system, you generally have two sensor technology options: panchromatic-based and Bayer pattern-based systems. The key question is whether you need the high-quality imaging performance of a panchromatic system or the simpler Bayer pattern-based approach. Important factors include geometric and radiometric accuracy, resolution, and how these affect downstream products like DSMs, DTMs, orthomosaics, 3D models, and analytics.

First, let’s check what it means!

Bayer Pattern Image Sensors

Bayer sensors, named after their inventor Bryce Bayer, use a Red-Green-Blue color filter array (CFA) layered on top of a single solid-state panchromatic image sensor (BAYER 1976). They mimic the physiology of the human eye by using twice as many green filters compared to red and blue ones. Although various CFA layouts have emerged over the years, the Bayer configuration remains the dominant design in the industry.

Source: Bayer filter – Wikipedia

Panchromatic Image Sensors

For applications requiring the highest resolving power, panchromatic sensors have always been the standard choice. They are often used in conjunction with lower-resolution multispectral data, combining the two through pansharpening. The absence of a color filter array (CFA) offers two key advantages. First, the sensor receives more light, equivalent to about one f-stop, at the pixel level. Second, no demosaicing (or interpolation) is needed, resulting in higher-resolution images compared to Bayer-based images with the same pixel pitch and significantly fewer artifacts.

Bonus for Geeks!

If you’re interested in delving deeper into the precise differences between panchromatic and Bayer pattern sensors, a detailed scientific paper provides intensive information.

Panchromatic sensors, featured in the Premium UltraCam line, can significantly enhance image quality. They add color through separate color cones (UltraCam Eagle) or a Bayer pattern (UltraCam Osprey, UltraCam Condor). However, all other current aerial cameras, including the UltraCam Merlin 4.1 as part of our Fundamental line, use Bayer pattern systems. This is crucial information for making fair comparisons across different systems.

Latest airborne camera systems with Bayer pattern sensors

  1. UltraCam Merlin 4.1
  2. Leica DMC-4
  3. Leica Content Mapper
  4. IGI DigiCams
  5. IGI Urban Mapper
  6. PhaseOne PAS PANA
  7. PhaseOne PAS 880
  8. Midas
  9. Rainpoo
  10. Swdc

Motion Compensation

The challenge of image motion blur

Image motion blur can occur due to different factors. First is translational motion blur, which results from the aircraft’s forward movement. This causes uniform blur across the entire image. Another type of blur stems from the plane’s rotation, including pitch, roll, and yaw. This kind of motion blur is more challenging to correct because it is non-uniform. And second, in oblique imagery, variations in scale within a single image also influence the degree of motion blur. The scale differences occur naturally, as the line of sight to objects varies from the top to the bottom of the image. The result is different amounts of motion blur in the image’s foreground and background, with the upper portions often showing less blur due to a longer line of sight compared to the lower edge.

How is image motion blur handled?

In aerial photogrammetry, the need for precise, clear images is critical, given the need to capture intricate details from a moving platform. To tackle this, a variety of mechanical and electronic solutions have been developed and widely adopted in aerial cameras. These include fast shutters to minimize exposure time, image stabilization systems to counteract movement, and advanced post-processing algorithms to enhance clarity.

Hardware Based Solutions

  1. Forward motion compensation (FMC) by time Delayed Integration (only applicable for CCD sensors)
  2. Mechanical forward motion compensation
  3. Blur Control Technology

Software-based solutions

  1. AMC (Adaptive Motion Compensation)

What is Adaptive Motion Compensation, “AMC”

Our proprietary Adaptive Motion compensation is our solution for multi-directional and scene-aware motion blur correction​. It corrects all types of motion blur, regardless of direction, image scale and scenery​.
The mathematical background of our proprietary Adaptive Motion Compensation technology is the so-called deconvolution or inverse convolution of an image. Knowing the point spread function a good approximation of the deconvolution kernel can be estimated.

The main benefits of AMC

  • Software-Based Solution: AMC is a software-driven solution, eliminating the need for mechanical components that can degrade over time or lead to malfunctions.
  • Versatile Handling of Motion Blur: It can effectively address all types of motion blur, whether from forward movement along the flight path or angular camera movements in any direction.
  • Adaptability to Blur Magnitude: The scene-aware AMC solution can adapt to varying blur intensities within the image, accommodating different object scales and positions to maintain image clarity.

Learn more about AMC

Camera Design

How many lenses are utilized, and what is their configuration — are the nadir cones truly nadir or slightly tilted? If titled, by how much?

Why is this important? Because with tilted nadir cones, pixels need to be interpolated as they create irregular pixel sizes.

In this example, you can clearly see the impact that a tilted camera design has on image quality. By opting for cameras without a tilt, you can mitigate some issues, such as variations in Ground Sampling Distance (GSD), to achieve more consistent image quality.

Image Processing

What image processing techniques are employed? How do these techniques improve the quality and usability of the captured images?

Image processing techniques used in UltraCam imagery revolve around True Pixel Processing (TPP). TPP is a comprehensive approach that accurately models the path and intensity of light rays passing through the camera’s optical system.
True Pixel Processing (TPP) brings significant enhancements to image quality in several areas: TPP…

  • Enhances noise handling in both shady and bright regions, preserving fine details in varying lighting conditions.
  • Improves the sharpness of images
  • Reduces zipper & aliasing artifacts, which are common in Bayer pattern sensors, ensuring smoother edges.
  • Reduces high-frequency moiré artifacts in Bayer pattern sensors, leading to cleaner, more natural images.
  • Improves correction of defective pixels

You can see the difference between TPP usage in this example below,
Original Image

With TPP applied

Bonus! For Geeks,
You can reach out to us for sample data from the UltraCam Merlin 4.1 to experience the high data quality firsthand by following this link:

UltraCam Merlin 4.1 Sample Data

System Footprint

What are the dimensions of the image footprint, and what is the base-to-height ratio? Is this ratio conducive to photogrammetric applications?

Additionally, how does the system mitigate the lean effect on the edges of super wide frames, which can render them unusable?

Two models of the UltraCam Merlin are available. The 2010 model is ideal for local projects, with two RGB and one NIR nadir sensor capturing images over 20,000 by 14,000 pixels. For larger projects, the 3020 model, with three RGB and two NIR sensors, provides a wider strip width exceeding 31,000 pixels.

It’s essential to consider the base-to-height ratio, which ensures sufficient overlap and stereoscopic coverage for accurate 3D terrain models. With 60% overlap, the 2010 model’s 80mm focal length yields a ratio of 1 to 3.7, similar to the UltraCam Eagle. The 3020 model’s 120mm focal length gives a ratio of 1 to 5.6. Both offer balanced image formats and base-to-height ratios.

When dealing with a footprint that’s very wide but quite short in length, the base-to-height ratio becomes imbalanced. This imbalance can lead to disadvantages in photogrammetric evaluation and feature extraction. It’s crucial to have a well-proportioned base-to-height ratio for the most effective and accurate photogrammetric outcomes.

Basic Camera Specifications

What are the size, weight, diameter, and power consumption specifications of the camera? How is the camera’s design optimized for installation in planes and to facilitate operation while in the air?

Specifically, is there a need to restrict mount movement because of bulky camera heads, and how does this impact the system’s overall functionality and flexibility?

The UltraCam Merlin 4.1 has a cylinder diameter of 32.5 cm. The 2010 model weighs 44 kg, while the 3020 model weighs 46 kg. Power consumption averages 230 W, peaking at 250 W.

Business Generation Efficiency

What is the system’s frame rate, and how does this affect operational efficiency? In case of issues, how quickly can support be provided? Assess the intuitiveness of the system’s operation.

Customers need a camera that covers large areas quickly, maximizes flight time, and offers rapid support. The UltraCam Merlin, with its 0.7-second frame rate, efficiently meets these requirements.

Vexcel’s intuitive and automated software minimizes training needs, offering a consistent experience across all UltraCam models.

The support provided by the Vexcel Global Support Team includes rapid remote and on-site assistance tailored to customer needs. Customers also gain access to experts for advice on hardware, processing optimization, and project planning.

In addition, Vexcel has worldwide support partners such as Atay Muhendislik Ltd. STI, covering Turkey and West Asian countries.

Data Processing Workflow

Does the workflow support high-performance processing without the need to switch tools? How does the workflow facilitate efficient, secure, and scalable data management?

Our UltraMap photogrammetric processing suite features five modules that process UltraCam raw data and generate products like point clouds, DSMs, DTMs, ortho imagery, and 3D textured TINs from captured imagery.

It allows you to create high-quality photogrammetric products with a modular workflow that streamlines everything from data ingestion to ortho export for nadir and oblique UltraCam imagery. This intuitive application provides efficient data interaction, editing, and powerful visualizations, with built-in quality control tools and options for manual adjustments.

UltraMap ensures successful project completion, regardless of size or delivery schedule, through flexible subscription licensing and distributed processing for optimal performance and scalability.

Flexibility For Business Growth

How does the system support scalability in the short and long term? Consider both hardware upgrades and software updates. Consider also a rental option to handle a short-term business. What additional support is available (webinars, user groups) for additional resources and troubleshooting?

The Vexcel ecosystem supports scalability through short- and long-term solutions. For short-term needs, we offer camera and software rentals, enabling customers to scale during peak flying periods or specific projects.

For long-term growth, we provide hardware upgrades and trade-in options for transitioning to the latest UltraCam technology.

As the only provider of panchromatic-based sensor systems in the market, we focus on building strong partnerships. We support customers through webinars and user groups for troubleshooting and additional resources, helping them scale their business effectively.

What Do You Think?

There you have it. 10-Step Checklist to make the right decision when choosing an aerial camera.

Now I’d like to hear from you.

Are you in a decision step on choosing an aerial camera?

And still confused?

Just let me know in the comments or use my DM box on my author page!

Thanks to Hürcan Atay for his contributions to this article! 

Suggested Articles

Leave a Reply

Your email address will not be published. Required fields are marked *

Fill out this field
Fill out this field
Please enter a valid email address.
You need to agree with the terms to proceed