Compact multispectral multi-camera imaging system for small UAVs

Torkildsen, Hans Erling; Haavardsholm, Trym Vegard; Opsahl, Thomas Olsvik; Datta, Urmila; Skaugen, Atle; Skauli, T.

doi:10.1117/12.2224495

Cited by 3 publications

(3 citation statements)

References 13 publications

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“…Additionally, we did not observe the possibility of channel expansion, the structure of the 6-channels was fixed, and it also had a wide single-channel spectrum (> 50 nm). Nonetheless, their applied research is still fascinating [10].…”

Section: Introductionmentioning

confidence: 99%

Spectral imaging based on micro-narrow multi-strip filter arrays

Guo,

Wu,

2023

Preprint

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Spectral imaging technology based on on-chip spectroscopy can serve numerous aerospace, industrial, and consumer electronics applications. With each application requiring a different set and number of spectral bands, the absence of scalable and high-cost custom spectroscopy solutions has prevented the widespread adoption of multispectral imaging (MSI). Although lithography and hard-mask steps continue to mature, it is still an expensive, cumbersome, and inflexible solution. In this paper, we demonstrate a compact, highly customizable imaging spectrometer scheme (licensed patent), which maintains high efficiencies (~85%), narrow bandwidth (~30 nm), and high average optical density (~OD2) across the visible to near-infrared spectrum. Spectral imaging experiments are conducted, and accurate reconstruction of sparse spectral image data is demonstrated. These results prove the scheme can achieve the expected target imaging and spectral measurement accuracy.

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Section: Introductionmentioning

confidence: 99%

Spectral imaging based on micro-narrow multi-strip filter arrays

Guo,

Wu,

2023

Preprint

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“…We have previously presented a novel imaging concept following this multimodal approach based on six bandpass filters arranged in a periodically repeating pattern. 1,2 Cameras based on patterned filters in the focal Figure 1. Raw image frame (right part) and a multispectral "push broom" still image (left part) reconstructed from this and preceding frames.…”

Section: Introductionmentioning

confidence: 99%

Compact multimodal multispectral sensor system for tactical reconnaissance

Haavardsholm

Opsahl²,

Skauli³

et al. 2022

Imaging Spectrometry XXV: Applications, Sensors, and Processing

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Multispectral imaging is an attractive sensing modality for small unmanned aerial vehicles (UAVs) in numerous military and civilian applications such as reconnaissance, target detection, and precision agriculture. Cameras based on patterned filters in the focal plane, such as conventional colour cameras, represent the most compact architecture for spectral imaging, but image reconstruction becomes challenging at higher band counts. We consider a camera configuration where six bandpass filters are arranged in a periodically repeating pattern in the focal plane. In addition, a large unfiltered region permits conventional monochromatic video imaging that can be used for situational awareness (SA), including estimating the camera motion and the 3D structure of the ground surface. By platform movement, the filters are scanned over the scene, capturing an irregular pattern of spectral samples of the ground surface. Through estimation of the camera trajectory and 3D scene structure, it is still possible to assemble a spectral image by fusing all measurements in software. The repeated sampling of bands enables spectral consistency testing, which can improve spectral integrity significantly. The result is a truly multimodal camera sensor system able to produce a range of image products. Here, we investigate its application in tactical reconnaissance by pushing towards on-board real-time spectral reconstruction based on visual odometry (VO) and full 3D reconstruction of the scene. The results are compared with offline processing based on estimates from visual simultaneous localisation and mapping (VSLAM) and indicate that the multimodal sensing concept has a clear potential for use in tactical reconnaissance scenarios.

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“…The imaging hardware concept used here has previously been tested with simplistic imaging geometries and processing methods [5], [6]. In this letter, we build on this work with the following contributions:…”

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confidence: 99%

Multimodal Multispectral Imaging System for Small UAVs

Haavardsholm

Skauli

Stahl

2020

IEEE Robot. Autom. Lett.

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Multispectral imaging is an attractive sensing modality for small unmanned aerial vehicles (UAVs) in numerous applications. The most compact spectral camera architecture is based on spectral filters in the focal plane. Vehicle movement can be used to scan the scene using multiple bandpass filters arranged perpendicular to the flight direction. With known camera trajectory and scene structure, it is possible to assemble a spectral image in software. In this letter, we demonstrate the feasibility of a novel concept for low-cost wide area multispectral imaging with integrated spectral consistency testing. Six bandpass filters are arranged in a periodically repeating pattern. Since different bands are recorded at different times and in different viewing directions, there is a risk of obtaining spectral artifacts in the image. We exploit the repeated sampling of bands to enable spectral consistency testing, which leads to significantly improved spectral integrity. In addition, an unfiltered region permits conventional 2D video imaging that can be used for image-based navigation and 3D reconstruction. The proposed multimodal imaging system was tested on a UAV in a realistic experiment. The results demonstrate that spectral reconstruction and consistency testing can be performed by image processing alone, based on visual simultaneous localization and mapping (VSLAM).

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Compact multispectral multi-camera imaging system for small UAVs

Cited by 3 publications

References 13 publications

Spectral imaging based on micro-narrow multi-strip filter arrays

Spectral imaging based on micro-narrow multi-strip filter arrays

Compact multimodal multispectral sensor system for tactical reconnaissance

Multimodal Multispectral Imaging System for Small UAVs

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