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Monocular Vision System for Fixed Altitude Flight of Unmanned Aerial Vehicles.

Huang KL, Chiu CC, Chiu SY, Teng YJ, Hao SS - Sensors (Basel) (2015)

Bottom Line: The UAV flight system can be set to fly at a fixed and relatively low altitude to obtain the same resolution of ground images.A forward-looking camera is mounted on the upside of the aircraft's nose.Experimental results show that the proposed system enables UAVs to obtain terrain images at constant resolution, and to detect the relative altitude along the flight path.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical and Electronic Engineering, Chung Cheng Institute of Technology, National Defense University, Taoyuan 33551, Taiwan. 1040510304@ndu.edu.tw.

ABSTRACT
The fastest and most economical method of acquiring terrain images is aerial photography. The use of unmanned aerial vehicles (UAVs) has been investigated for this task. However, UAVs present a range of challenges such as flight altitude maintenance. This paper reports a method that combines skyline detection with a stereo vision algorithm to enable the flight altitude of UAVs to be maintained. A monocular camera is mounted on the downside of the aircraft's nose to collect continuous ground images, and the relative altitude is obtained via a stereo vision algorithm from the velocity of the UAV. Image detection is used to obtain terrain images, and to measure the relative altitude from the ground to the UAV. The UAV flight system can be set to fly at a fixed and relatively low altitude to obtain the same resolution of ground images. A forward-looking camera is mounted on the upside of the aircraft's nose. In combination with the skyline detection algorithm, this helps the aircraft to maintain a stable flight pattern. Experimental results show that the proposed system enables UAVs to obtain terrain images at constant resolution, and to detect the relative altitude along the flight path.

No MeSH data available.


Flying direction detection algorithm.
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sensors-15-16848-f003: Flying direction detection algorithm.

Mentions: In this study, we use the downward camera to capture ground images and detect the direction of flight with respect to the ground. A flowchart of the flying direction detection algorithm is shown in Figure 3. First, in the preprocessing phase, the downward-looking camera captures ground images of 480 ×640 pixel resolution. The National Television System Committee (NTSC) format of video signals means that the captured images suffer from the interlace problem, which influences image recognition. Therefore, the captured images must be de-interlaced to 240 × 640 pixels. The processed images are transformed to gray images, and are then segmented into non-overlapping blocks. In general, the reliability of the block-matching result is proportional to the block size. Considering the reliability of the block-matching result and the number of blocks, the block size is chosen to be 32 × 32 pixels.


Monocular Vision System for Fixed Altitude Flight of Unmanned Aerial Vehicles.

Huang KL, Chiu CC, Chiu SY, Teng YJ, Hao SS - Sensors (Basel) (2015)

Flying direction detection algorithm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541911&req=5

sensors-15-16848-f003: Flying direction detection algorithm.
Mentions: In this study, we use the downward camera to capture ground images and detect the direction of flight with respect to the ground. A flowchart of the flying direction detection algorithm is shown in Figure 3. First, in the preprocessing phase, the downward-looking camera captures ground images of 480 ×640 pixel resolution. The National Television System Committee (NTSC) format of video signals means that the captured images suffer from the interlace problem, which influences image recognition. Therefore, the captured images must be de-interlaced to 240 × 640 pixels. The processed images are transformed to gray images, and are then segmented into non-overlapping blocks. In general, the reliability of the block-matching result is proportional to the block size. Considering the reliability of the block-matching result and the number of blocks, the block size is chosen to be 32 × 32 pixels.

Bottom Line: The UAV flight system can be set to fly at a fixed and relatively low altitude to obtain the same resolution of ground images.A forward-looking camera is mounted on the upside of the aircraft's nose.Experimental results show that the proposed system enables UAVs to obtain terrain images at constant resolution, and to detect the relative altitude along the flight path.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical and Electronic Engineering, Chung Cheng Institute of Technology, National Defense University, Taoyuan 33551, Taiwan. 1040510304@ndu.edu.tw.

ABSTRACT
The fastest and most economical method of acquiring terrain images is aerial photography. The use of unmanned aerial vehicles (UAVs) has been investigated for this task. However, UAVs present a range of challenges such as flight altitude maintenance. This paper reports a method that combines skyline detection with a stereo vision algorithm to enable the flight altitude of UAVs to be maintained. A monocular camera is mounted on the downside of the aircraft's nose to collect continuous ground images, and the relative altitude is obtained via a stereo vision algorithm from the velocity of the UAV. Image detection is used to obtain terrain images, and to measure the relative altitude from the ground to the UAV. The UAV flight system can be set to fly at a fixed and relatively low altitude to obtain the same resolution of ground images. A forward-looking camera is mounted on the upside of the aircraft's nose. In combination with the skyline detection algorithm, this helps the aircraft to maintain a stable flight pattern. Experimental results show that the proposed system enables UAVs to obtain terrain images at constant resolution, and to detect the relative altitude along the flight path.

No MeSH data available.