A Study on the Variations of Inner Orientation Parameters of a Hyperspectral Frame Camera

Tommaselli, Antônio Maria Garcia; Santos, Lucas Dias; Berveglieri, Adilson; Oliveira, Raquel Alves de; Honkavaara, Eija

doi:10.5194/isprs-archives-xlii-1-429-2018

Cited by 7 publications

(8 citation statements)

References 8 publications

(9 reference statements)

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“…Indeed, from 20 to 90 min, a progressive increase in the magnitude of the DC values was reported. The similar trend between Figure 5 and Figure 8 is due to the effect of the dark current signal on the total signal; therefore, considering the dark current trend and its temporal dynamic during the warm-up phase is essential to obtain a clean spectral signal [ 34 , 35 ]. Our results reveal an increasing dark current signal with time during the warm-up phase following the camera switch on, until a stabilization is reached after about 90 min.…”

Section: Resultsmentioning

confidence: 99%

“…Despite the technological developments of the low-cost PHCs, critical aspects are reported during acquisition and data processing, such as the long instrumental warm-up time, the presence of spectral discontinuities in correspondence of the spectral border region of different CMOS sensors, signal jumps, and high levels of background noise. The unavoidable limitations due to the low cost cannot be resolved with technology; thus, it is crucial to reduce them with careful and optimized data processing and sensor operation [ 34 , 35 , 36 ].…”

Section: Introductionmentioning

confidence: 99%

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A Novel Correction Methodology to Improve the Performance of a Low-Cost Hyperspectral Portable Snapshot Camera

Genangeli,

Avola,

Bindi

et al. 2023

Sensors

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The development of spectral sensors (SSs) capable of retrieving spectral information have opened new opportunities to improve several environmental and agricultural practices, e.g., crop breeding, plant phenotyping, land use monitoring, and crop classification. The SSs are classified as multispectral and hyperspectral (HS) based on the number of the spectral bands resolved and sampled during data acquisition. Large-scale applications of the HS remain limited due to the cost of this type of technology and the technical difficulties in hyperspectral data processing. Low-cost portable hyperspectral cameras (PHCs) have been progressively developed; however, critical aspects associated with data acquisition and processing, such as the presence of spectral discontinuities, signal jumps, and a high level of background noise, were reported. The aim of this work was to analyze and improve the hyperspectral output of a PHC Senop HSC-2 device by developing a general use methodology. Several signal gaps were identified as falls and jumps across the spectral signatures near 513, 650, and 930 nm, while the dark current signal magnitude and variability associated with instrumental noise showed an increasing trend over time. A data correction pipeline was successfully developed and tested, leading to 99% and 74% reductions in radiance signal jumps identified at 650 and 830 nm, respectively, while the impact of noise on the acquired signal was assessed to be in the range of 10% to 15%. The developed methodology can be effectively applied to other low-cost hyperspectral cameras.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Novel Correction Methodology to Improve the Performance of a Low-Cost Hyperspectral Portable Snapshot Camera

Genangeli,

Avola,

Bindi

et al. 2023

Sensors

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“…The range marked as sensor noise seen in Figs. 4 A.2 and 5 A.2 is caused by a known technical issue at 640 nm in the Rikola imager that does not affect the rest of the spectrum 27 . Additionally, we plot the spectral signatures at locations showing no absorption features indicating the absence of REEs (Point 7 from Marinkas Quellen and point 1 from Siilinjärvi).…”

Section: Resultsmentioning

confidence: 99%

Detection of REEs with lightweight UAV-based hyperspectral imaging

Booysen

Jackisch

Lorenz

et al. 2020

Sci Rep

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Rare earth elements (REEs) supply is important to ensure the energy transition, e-mobility and ultimately to achieve the sustainable development goals of the United Nations. Conventional exploration techniques usually rely on substantial geological field work including dense in-situ sampling with long delays until provision of analytical results. However, this approach is limited by land accessibility, financial status, climate and public opposition. Efficient and innovative methods are required to mitigate these limitations. The use of lightweight unmanned aerial vehicles (UAVs) provides a unique opportunity to conduct rapid and non-invasive exploration even in socially sensitive areas and in relatively inaccessible locations. We employ drones with hyperspectral sensors to detect REEs at the earth’s surface and thus contribute to a rapidly evolving field at the cutting edge of exploration technologies. We showcase for the first time the direct mapping of REEs with lightweight hyperspectral UAV platforms. Our solution has the advantage of quick turn-around times (< 1 d), low detection limits (< 200 ppm for Nd) and is ideally suited to support exploration campaigns. This procedure was successfully tested and validated in two areas: Marinkas Quellen, Namibia, and Siilinjärvi, Finland. This strategy should invigorate the use of drones in exploration and for the monitoring of mining activities.

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“…The spectral artefact of the HSI camera between~636-650 nm, is caused by its two-sensor design [67] and was removed. We recommend an HSI camera setting of 50 bands with 8 nm spectral resolution as most effective to maintain a balance between spectral density and SNR.…”

Section: Consequences Of Uas Imagingmentioning

confidence: 99%

Drone-Borne Hyperspectral and Magnetic Data Integration: Otanmäki Fe-Ti-V Deposit in Finland

et al. 2019

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The technical evolution of unmanned aerial systems (UAS) for mineral exploration advances rapidly. Recent sensor developments and improved UAS performance open new fields for research and applications in geological and geophysical exploration among others. In this study, we introduce an integrated acquisition and processing strategy for droneborne multisensor surveys combining optical remote sensing and magnetic data. We deploy both fixedwing and multicopter UAS to characterize an outcrop of the Otanmäki FeTiV deposit in central Finland. The lithology consists mainly of gabbro intrusions hosting ore bodies of magnetiteilmenite. Large areas of the outcrop are covered by lichen and low vegetation. We use two droneborne multi and hyperspectral cameras operating in the visible to nearinfrared parts of the electromagnetic spectrum to identify dominant geological features and the extents of ore bodies via ironindicating proxy minerals. We apply band ratios and unsupervised and supervised image classifications on the spectral data, from which we can map surficial ironbearing zones. We use two setups with threeaxis fluxgate magnetometers deployed both by a fixedwing and a multicopter UAS to measure the magnetic field at various flight altitudes (15 m, 40 m, 65 m). The total magnetic intensity (TMI) computed from the individual components is used for further interpretation of ore distribution. We compare to traditional magnetic groundbased survey data to evaluate the UASbased results. The measured anomalies and spectral data are validated and assigned to the outcropping geology and ore mineralization by performing surface spectroscopy, portable Xray fluorescence (pXRF), magnetic susceptibility, and traditional geologic mapping. Locations of mineral zones and magnetic anomalies correlate with the established geologic map. The integrated survey strategy allowed a straightforward mapping of ore occurrences. We highlight the efficiency, spatial resolution, and reliability of UAS surveys. Acquisition time of magnetic UAS surveying surpassed ground surveying by a factor of 20 with a comparable resolution. The proposed workflow possibly facilitates surveying, particularly in areas with complicated terrain and of limited accessibility, but highlights the remaining challenges in UAS mapping.

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A Study on the Variations of Inner Orientation Parameters of a Hyperspectral Frame Camera

Cited by 7 publications

References 8 publications

A Novel Correction Methodology to Improve the Performance of a Low-Cost Hyperspectral Portable Snapshot Camera

A Novel Correction Methodology to Improve the Performance of a Low-Cost Hyperspectral Portable Snapshot Camera

Detection of REEs with lightweight UAV-based hyperspectral imaging

Drone-Borne Hyperspectral and Magnetic Data Integration: Otanmäki Fe-Ti-V Deposit in Finland

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