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Auteur R. Wackrow |
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Motion blur disturbs – the influence of motion-blurred images in photogrammetry / T. Sieberth in Photogrammetric record, vol 29 n° 148 (December 2014 - February 2015)
[article]
Titre : Motion blur disturbs – the influence of motion-blurred images in photogrammetry Type de document : Article/Communication Auteurs : T. Sieberth, Auteur ; R. Wackrow, Auteur ; Jim H. Chandler, Auteur Année de publication : 2014 Article en page(s) : pp 434 – 453 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s)
[Termes IGN] étalonnage de capteur (imagerie)
[Termes IGN] flou
[Termes IGN] image à haute résolution
[Termes IGN] tâche claire
[Termes IGN] traitement d'imageRésumé : (Auteur) Unmanned aerial vehicles (UAVs) have become an interesting and active research topic for photogrammetry. Current research is based on images acquired by UAVs which have a high ground resolution and good spectral resolution due to low flight altitudes combined with a high-resolution camera. One of the main problems preventing full automation of data processing of UAV imagery is the unknown degradation effect of blur caused by camera movement during image acquisition. The purpose of this paper is to analyse the influence of blur on photogrammetric image processing. Images with precisely known motion blur were produced to determine the effect. It was found that even small blurs affect normal photogrammetric processes significantly. Although operator intervention might be time consuming, it can ensure that the results are still of acceptable accuracy. Numéro de notice : A2014-649 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/phor.12082 Date de publication en ligne : 16/12/2014 En ligne : https://doi.org/10.1111/phor.12082 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75095
in Photogrammetric record > vol 29 n° 148 (December 2014 - February 2015) . - pp 434 – 453[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 106-2014041 RAB Revue Centre de documentation En réserve L003 Disponible Direct exterior orientation determination for a low-cost heritage recording system / M. Kirschhöfer in Photogrammetric record, vol 27 n° 140 (December 2012 - February 2013)
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Titre : Direct exterior orientation determination for a low-cost heritage recording system Type de document : Article/Communication Auteurs : M. Kirschhöfer, Auteur ; Jim H. Chandler, Auteur ; R. Wackrow, Auteur Année de publication : 2012 Article en page(s) : pp 443 - 461 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie terrestre
[Termes IGN] antenne GNSS
[Termes IGN] caméra numérique
[Termes IGN] données localisées des bénévoles
[Termes IGN] orientation externe
[Termes IGN] patrimoine culturel
[Termes IGN] patrimoine immobilier
[Termes IGN] photogrammétrie terrestreRésumé : (Auteur) Close range photogrammetry has proved effective as a cost-effective and easy-to-use method for cultural heritage recording. Off-the-shelf digital cameras can be used to rapidly acquire data at low cost, allowing non-experts to become more involved in their local heritage, an important aspiration identified in this collaboration between English Heritage and Loughborough University. To achieve this while also allowing for measurements in a 3D national reference system, a recording system has been developed that is capable of deriving the exterior orientation during exposure directly and cheaply. The system comprises a digital camera, a small 3D orientation sensor and a GNSS antenna, assembled in a frame that allows calibration of the offsets between the components. Test field data was used to investigate calibration precision and stability as well as achievable absolute and relative accuracy. The results of data analysis indicate that the system can meet the accuracy requirements for medium accuracy heritage recording, even with slightly unstable offset calibration values. Numéro de notice : A2012-626 Affiliation des auteurs : non IGN Thématique : IMAGERIE/SOCIETE NUMERIQUE Nature : Article DOI : 10.1111/j.1477-9730.2012.00701.x Date de publication en ligne : 18/12/2012 En ligne : https://doi.org/10.1111/j.1477-9730.2012.00701.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32072
in Photogrammetric record > vol 27 n° 140 (December 2012 - February 2013) . - pp 443 - 461[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 106-2012041 RAB Revue Centre de documentation En réserve L003 Disponible Parameterising internal camera geometry with focusing distance / E. Sanz-Ablanedo in Photogrammetric record, vol 27 n° 138 (June - August 2012)
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Titre : Parameterising internal camera geometry with focusing distance Type de document : Article/Communication Auteurs : E. Sanz-Ablanedo, Auteur ; Jim H. Chandler, Auteur ; R. Wackrow, Auteur Année de publication : 2012 Article en page(s) : pp 210 - 226 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s)
[Termes IGN] étalonnage de chambre métrique
[Termes IGN] étalonnage géométrique
[Termes IGN] longueur focale
[Termes IGN] orientation interne
[Termes IGN] photogrammétrie terrestreRésumé : (Auteur) A study on the variation of internal camera geometry (principal distance, principal point position and lens distortion parameters) with different focus distances has been conducted. Results demonstrate that variations of parameters are continuous and predictable, allowing a new way to describe internal camera geometry. The classical constant parameters, c, x p , y p , K 1 , K 2 , P 1 and P 2 , are replaced by continuous functions, c(y), x p (y), y p(y), K 1 (y), K 2 (y), P 1 (y) andP 2 (y), where y is a variable describing the focus position. Incorporation of y as a metadata tag (for example, Exif header) of a photograph jointly with a parameterised definition of camera geometry would allow full use of the autofocus camera function; enabling maximum effective depth of field, better match of the plane of focus with the object’s position and higher reliability. Additionally, conducted tests suggest the parameterised definition of internal geometry could help to locate and correct linear dependences between adjusted parameters, potentially improving the precision and accuracy of calibration. Numéro de notice : A2012-307 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2012.00677.x Date de publication en ligne : 20/06/2012 En ligne : https://doi.org/10.1111/j.1477-9730.2012.00677.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31753
in Photogrammetric record > vol 27 n° 138 (June - August 2012) . - pp 210 - 226[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 106-2012021 RAB Revue Centre de documentation En réserve L003 Disponible Minimising systematic error surfaces in digital elevation models using oblique convergent imagery / R. Wackrow in Photogrammetric record, vol 26 n° 133 (March - May 2011)
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Titre : Minimising systematic error surfaces in digital elevation models using oblique convergent imagery Type de document : Article/Communication Auteurs : R. Wackrow, Auteur ; Jim H. Chandler, Auteur Année de publication : 2011 Article en page(s) : pp 16 - 31 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques
[Termes IGN] angle de visée
[Termes IGN] déformation de surface
[Termes IGN] erreur systématique
[Termes IGN] image oblique
[Termes IGN] inondation
[Termes IGN] modèle numérique de surface
[Termes IGN] photogrammétrie terrestreRésumé : (Auteur) There are increasing opportunities to use consumer-grade digital cameras, particularly if accurate spatial data can be captured. Research recently conducted at Loughborough University identified residual systematic error surfaces or domes discernible in digital elevation models (DEMs). These systematic effects are often associated with such cameras and are caused by slightly inaccurate estimated lens distortion parameters. A methodology that minimises the systematic error surfaces was therefore developed, using a mildly convergent image configuration in a vertical perspective. This methodology was tested through simulation and a series of practical tests. This paper investigates the potential of the convergent configuration to minimise the error surfaces, even if the geometrically more complex oblique perspective is used. Initially, simulated data was used to demonstrate that an oblique convergent image configuration can minimise remaining systematic error surfaces using various imaging angles. Additionally, practical tests using a laboratory testfield were conducted to verify results of the simulation. The need to develop a system to measure the topographic surface of a flooding river provided the opportunity to verify the findings of the simulation and laboratory test using real data. Results of the simulation process, the laboratory test and the practical test are reported in this paper and demonstrate that an oblique convergent image configuration eradicates the systematic error surfaces which result from inaccurate lens distortion parameters. This approach is significant because by removing the need for an accurate lens model it effectively improves the accuracies of digital surface representations derived using consumer-grade digital cameras. Carefully selected image configurations could therefore provide new opportunities for improving the quality of photogrammetrically acquired data. Numéro de notice : A2011-076 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2011.00623.x Date de publication en ligne : 16/03/2011 En ligne : https://doi.org/10.1111/j.1477-9730.2011.00623.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30857
in Photogrammetric record > vol 26 n° 133 (March - May 2011) . - pp 16 - 31[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 106-2011011 RAB Revue Centre de documentation En réserve L003 Disponible Geometric consistency and stability of consumer-grade digital cameras for accurate spatial measurement / R. Wackrow in Photogrammetric record, vol 22 n° 118 (June - August 2007)
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Titre : Geometric consistency and stability of consumer-grade digital cameras for accurate spatial measurement Type de document : Article/Communication Auteurs : R. Wackrow, Auteur ; Jim H. Chandler, Auteur ; P. Bryan, Auteur Année de publication : 2007 Article en page(s) : pp 121 - 134 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s)
[Termes IGN] analyse comparative
[Termes IGN] caméra numérique
[Termes IGN] cohérence géométrique
[Termes IGN] distorsion d'image
[Termes IGN] élément d'orientation interne
[Termes IGN] erreur systématique
[Termes IGN] étalonnage de capteur (imagerie)
[Termes IGN] Leica Photogrammetry Suite
[Termes IGN] précision géométrique (imagerie)
[Termes IGN] prise de vue terrestreRésumé : (Auteur) It is known that uncertain internal geometry of consumer-grade digital cameras limits the accuracy of data that can be extracted. These cameras can be calibrated, but the validity of calibration data over a period of time should be carefully assessed before subsequent photogrammetric measurement. This paper examines the geometric stability and manufacturing consistency of a typical low-cost digital camera (Nikon Coolpix 5400) by estimating the degree of similarity between interior orientation parameters (IOP), established over a 1-year period. Digital elevation models (DEMs) were extracted with differing IOP, and accuracies were compared using data obtained from seven identical cameras. An independent self-calibrating bundle adjustment (GAP) and the Leica Photogrammetry Suite (LPS) software were used to provide these data-sets. Results are presented that indicate the potential of these cameras to maintain their internal geometry in terms of temporal stability and manufacturing consistency. This study also identifies residual systematic error surfaces or ‘‘domes’’, discernible in ‘‘DEMs of difference’’. These are caused by slightly inaccurately estimated lens distortion parameters, which effectively constrain the accuracies achievable with this class of sensor. Copyright RS&PS + Blackwell Publishing Numéro de notice : A2007-363 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2007.00436.x En ligne : https://doi.org/10.1111/j.1477-9730.2007.00436.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28726
in Photogrammetric record > vol 22 n° 118 (June - August 2007) . - pp 121 - 134[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 106-07021 RAB Revue Centre de documentation En réserve L003 Disponible