Reliability of the Geometric Calibration of an Hyperspectral Frame Camera

Musci, Maria Angela; Aicardi, Irene; Dabove, Paolo; Lingua, Andrea Maria

doi:10.5194/isprs-archives-xlii-2-w13-1701-2019

Cited by 3 publications

(2 citation statements)

References 13 publications

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“…It is worth mentioning at this point that for aerial applications, geometric calibration of the images is also advised. This can be achieved by ca lculating the extrinsic and intrinsic parameters of the lenses and imagers by simply imaging a chessboard of known dimensions (Musci et al, 2019). Again, for applications that require high spatial resolution, sharpening of the image is also advised, using a well-defined point spread function.…”

Section: 𝑹𝒆𝒍𝒂𝒕𝒊𝒗𝒆 𝑹𝒆𝒇𝒍𝒆𝒄𝒕𝒂𝒏𝒄𝒆 𝒊 𝒋 = ∫ 𝑹𝒆𝒇𝒍𝒆𝒄𝒕𝒂𝒏𝒄𝒆 𝑺𝒕𝒂𝒏𝒅𝒂𝒓𝒅 𝒊 ( 𝝀 ) •𝑺...mentioning

confidence: 99%

Calibrating a snapshot mosaic hyperspectral imaging system suitable for static and aerial applications

Zempila¹,

Hamilton²,

Mortimer³

2023

Hyperspectral Imaging and Applications II

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Radiometric calibration of all optical sensors is a key component to achieve high accuracy data, which is traceable to international standards and repeatable through time. This study introduces a hyperspectra l imaging (HSI) system that RAL Space has developed and presents a thorough analysis of the radiometric reflectance calibration chain required for both static and aerial applications, where the HSI system is mounted on a n Unoccupied Aerial System (UAS). RAL Space HSI system comprises two commercially available Ximea snapshot mosaic imagers, one sensitive in the visible (VIS) and the other in the near infrared (NIR) spectral ranges, that are coupled with a dedicated PC and customized LabVIEW code for the capture, process and storage of the raw hyperspectral information (hypercubes). Both imagers are optically characterized for their electrical gain and offset, the vignetting and stray light effects, while the spectral response of each band has also been determined. The corrected digital numbers (DN) are then translated into reflectance values with the use of reflectance standards. For the aerial surveys, an additional step has been developed into the calibration chain that corrects for any changes in ambient illumination during flight with the use of ground based upward-looking measured spectra.Future work will include any correction needed due to temperature dependencies of the calibration chain steps.

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confidence: 99%

Calibrating a snapshot mosaic hyperspectral imaging system suitable for static and aerial applications

Zempila¹,

Hamilton²,

Mortimer³

2023

Hyperspectral Imaging and Applications II

View full text Add to dashboard Cite

show abstract

“…Indeed, a significant number of applications of SfM/UAV photogrammetry with pre-calibrated cameras have relied on available chessboard-based calibration software (recent examples include Cucchiaro et al, 2018;Erenoğlu & Erenoğlu, 2018;Halik & Smaczýnski, 2018;Menge & Lohsträter, 2018;Probst et al, 2018;Ventura et al, 2018;Wierzbicki, 2018;Burnett et al, 2019;Javadnejad et al, 2019;Kölling et al, 2019;Luppichini et al, 2019;Mahmood et al, 2019;Musci et al, 2019;Yurtseven, 2019), often without particular considerations, e.g. concerning focusing distance and frame coverage.…”

Section: Introductionmentioning

confidence: 99%

Camera Calibration Using Multiple Unordered Coplanar Chessboards

Γραμματικόπουλος

Adam

Petsa

et al. 2019

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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Abstract. The now widely available and highly popular among non-expert users, particularly in the context of UAV photogrammetry, Structure-from-Motion (SfM) pipelines have also further renewed the interest in the issue of automatic camera calibration. The well-documented requirements for robust self-calibration cannot be always met, e.g. due to restrictions in time and cost, absence of ground control and image tilt, terrain morphology, unsuitable flight configuration etc.; hence, camera pre-calibration is frequently recommended. In this context, users often resort to flexible, user-friendly tools for camera calibration based on 2D coded patterns (primarily ordinary chessboards). Yet, the physical size of such patterns poses obvious limitations. This paper discusses the alternative of extending the size of the calibration object by using multiple unordered coplanar chessboards, which might accommodate much larger imaging distances. This is done initially by a detailed simulation to show that – in terms of geometry – this could be a viable alternative to single patterns. A first algorithmic implementation is then laid out, and results from real multi-pattern configurations, both ordered and unordered, are successfully compared. However, aspects of the proposed approach need to be further studied for its reliable practical employment.

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Geomatic Contribution for the Restoration Project of the Valentino Castle Green Room. From Data Acquisition to Integrated Documentation

Patrucco

Chiabrando

Dameri

et al. 2020

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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Abstract. In the framework of restoration operations, valuable assistance can be supplied from innovative techniques and methods developed in the field of Geomatics. Over the years, this continuous collaboration has produced synergistic and interdisciplinary results that have been successfully contributing to heritage conservation and valorisation. In the case of the current research, thorough multisensory investigations have been performed in order to provide a deeper knowledge of the Green Room of the Valentino Castle in Turin and to support the planning of the future restoration works that will involve this valuable asset. In the framework of this experience, four LiDAR systems have been employed in order to evaluate the different results obtainable from the sensors. Additionally, a complete photogrammetric close-range survey has been carried out, and some tests were completed using a hyperspectral camera. The workflow followed during the current research is described in this paper, and a comparison between the obtained outputs is proposed, focusing on the characteristics of these metric products, useful and sometimes necessary in the framework of the restoration project. Besides, some considerations on the advantages and the issues connected with the use of these reality-based data as a starting point for HBIM (Heritage Building Information Modeling) model generation are proposed, along with some observations about the potentialities of a photogrammetric co-registration approach using spectrum technologies for deterioration/decay detection and monitoring of heritage.

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Reliability of the Geometric Calibration of an Hyperspectral Frame Camera

Cited by 3 publications

References 13 publications

Calibrating a snapshot mosaic hyperspectral imaging system suitable for static and aerial applications

Calibrating a snapshot mosaic hyperspectral imaging system suitable for static and aerial applications

Camera Calibration Using Multiple Unordered Coplanar Chessboards

Geomatic Contribution for the Restoration Project of the Valentino Castle Green Room. From Data Acquisition to Integrated Documentation

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