An Unmanned Aerial Vehicle (UAV) (Figure 1) is an aircraft without a human pilot on-board. It is operated either remotely or by means of pre-programmed flight plans and other automated guidance systems. Besides being used in military operations, UAVs are now increasingly used in civil applications such as law enforcement, firefighting, environmental monitoring, and assessment of natural disasters.
Figure 1. An Unmanned Aerial Vehicle.
Imaging Subsystem of an UAV
An UAV’s imaging subsystem comprises many different enabling technologies such as sensors, wireless communications and computing devices. A typical platform features multiple digital cameras that are interfaced to a geospatial processor. A data networking switch fabric is used for the distribution of geo-referenced imaging data, making system configuration flexible, simple and extensible.
The camera is triggered by the control computer, which also records and prepares images for distribution and stores information such as camera settings, position and altitude that are supplied together with the images as metadata. The information is then transmitted to the UAV ground station through a high-tech wireless network that can achieve wireless data retrieval of large files in real-time. Modern UAVs can capture and stream multi-megapixel, large format images and metadata.
Camera Requirements for UAV Applications
Cameras used on UAVs need to meet a set of application requirements that are very specific to the industry. The three specific categories of airborne digital cameras include small format, a medium format and a large format. Small format cameras are equipped with up to 16MP sensors, while medium format cameras use sensors between 16 and 50MP, and large format cameras deploy more than 50MP sensors. The following are the performance features required for a digital camera deployed in UAV applications:
- Superior image quality.
- High-resolution sensors that can provide the level of details required from an aerial image
- Must have a reliable camera shutter for successful UAV operations.
- Must capture images in a RAW format, which can provide finer details owing to the extra data each pixel contains.
- Needs to ensure blur-free images in each specific flight condition.
- Needs to have minimal noise to improve the light detection of the sensor in low light environments such as UAV applications.
- A camera with faster frame rates enables greater UAV travel speed, resulting in increased covertness and shorter flight times.
- Needs to have a high-speed data interface to enable faster image transfer.
- System flexibility is crucial for customizing the UAV performance and keeping costs under control and can be realized by using standard data interfaces, which can be utilized in tandem with a common software architecture supporting a suite of cameras.
- Robust construction to withstand challenging operational environments such as UAV applications.
- Higher quality lenses to support superior resolutions with the appropriate performance level.
Lumenera's Lg11059 Camera
The Lg11059 camera (Figure 2) from Lumenera is an ideal imaging system for demanding environments such as UAVs. The 11MP industrial-grade camera offers 5fps at full 4008 x 2672 resolution. It is equipped with a fully integrated Canon EF lens controller and a 35 mm high-resolution CCD sensor. Moreover, with a fully global electronic shutter, it can capture images at a precise moment where all rows are snapped at the same light intensity and time. This yields blur-free high-speed images.
Figure 2. The Lg11059 Camera.
The Lg11059 camera makes use of its high-quality CCD sensor to provide either vivid color or very sensitive visible light and near IR monochromatic images. Using the standard API interface or the GigE Vision interface, the camera is able to control full streaming of uncompressed video in conjunction with still image captures.
Region of interest and binning modes facilitate the camera to operate at faster frame rates (14fps at 640 x 480 resolution) while delivering only the required image data. Image capture synchronization is performed through a hardware or software trigger, and is supported by 32-MB on board memory for frame buffering to ascertain image delivery.
The Lg11059 camera has a robust and compact design with dimensions of 76.2 x 76.2 x 82.6mm, making it suitable to be deployed into compact systems. The combination of digital I/O interface, power connector, and fully locking Gigabit Ethernet cabling provides a true plug-and-play installation, reducing camera clutter with only one standard cable.
Simplified I/O cabling is achieved through a locking Hirose connector that supports three input and four output ports, which can be manually or automatically controlled through software. Reliable operation is ensured using locking connector even under high vibration environment. The absence of fans or cooling holes further increases the reliability of the camera. An UAV featuring the Lg11059 camera is illustrated in Figure 3.
Figure 3. An UAV featuring the Lg11059 camera.
The Lumenera Camera SDK offers a comprehensive range of functions and features that enable users to optimize the performance of their camera within their application. The SDK supports all USB and GigE based cameras.
The availability of .NET API, Windows API, Microsoft DirectX/DirectShow interfaces provides the choice of application development environments from VB.NET to C/C++ or C#.NET. The .NET API interface is provided with full inline IntelliSense auto-completion and documentation as well as with a full API manual that describes all the camera functions and features.
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This information has been sourced, reviewed and adapted from materials provided by Lumenera Corporation.
For more information on this source, please visit Lumenera Corporation.