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An improved segmentation approach for planar surfaces from undestructured 3D point clouds / T.M. Awwad in Photogrammetric record, vol 25 n° 129 (March - May 2010)  

Public [article]  inPhotogrammetric record > vol 25 n° 129 (March - May 2010) . - pp 5 - 23 Titre : An improved segmentation approach for planar surfaces from undestructured 3D point clouds Type de document : Article/Communication Auteurs : T.M. Awwad, Auteur ; Q. Zhu, Auteur ; Z. Du, Auteur ; Y. Zhang, Auteur Année de publication : 2010 Article en page(s) : pp 5 - 23 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] extraction de traits caractéristiques [Termes IGN] Ransac (algorithme) [Termes IGN] segmentation d'image [Termes IGN] semis de points [Termes IGN] surface plane Résumé : (Auteur) The extraction of object features from massive unstructured point clouds with different local densities, especially in the presence of random noisy points, is not a trivial task even if that feature is a planar surface. Segmentation is the most important step in the feature extraction process. In practice, most segmentation approaches use geometrical information to segment the 3D point cloud. The features generally include the position of each point (X, Y and Z), locally estimated surface normals and residuals of best fitting surfaces; however, these features could be affected by noisy points and in consequence directly affect the segmentation results. Therefore, massive unstructured and noisy point clouds also lead to bad segmentation (over-segmentation, under-segmentation or no segmentation). While the RANSAC (random sample consensus) algorithm is effective in the presence of noise and outliers, it has two significant disadvantages, namely, its efficiency and the fact that the plane detected by RANSAC may not necessarily belong to the same object surface; that is, spurious surfaces may appear, especially in the case of parallel-gradual planar surfaces such as stairs. The innovative idea proposed in this paper is a modification for the RANSAC algorithm called Seq-NV-RANSAC. This algorithm checks the normal vector (NV) between the existing point clouds and the hypothesised RANSAC plane, which is created by three random points, under an intuitive threshold value. After extracting the first plane, this process is repeated sequentially (Seq) and automatically, until no planar surfaces can be extracted from the remaining points under the existing threshold value. This prevents the extraction of spurious surfaces, brings an improvement in quality to the computed attributes and increases the degree of automation of surface extraction. Thus the best fit is achieved for the real existing surfaces. Copyright RS&PS + Blackwell Publishing Numéro de notice : A2010-060 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2009.00564.x Date de publication en ligne : 11/03/2010 En ligne : https://doi.org/10.1111/j.1477-9730.2009.00564.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30256 [article]

Exemplaires(1)

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106-2010011	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Interest operators for feature-based matching in close range photogrammetry / I. Jazayeri in Photogrammetric record, vol 25 n° 129 (March - May 2010)  

Public [article]  inPhotogrammetric record > vol 25 n° 129 (March - May 2010) . - pp 24 - 41 Titre : Interest operators for feature-based matching in close range photogrammetry Type de document : Article/Communication Auteurs : I. Jazayeri, Auteur ; Clive Simpson Fraser, Auteur Année de publication : 2010 Article en page(s) : pp 24 - 41 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes IGN] appariement de points [Termes IGN] bloc d'images [Termes IGN] filtre de Wallis [Termes IGN] photogrammétrie métrologique [Termes IGN] point d'intérêt Résumé : (Auteur) Although automated object surface reconstruction via feature-based matching is commonly employed in both stereoscopic close range and topographic photogrammetry, it has rarely been used in conjunction with multi-image, convergent photogrammetric networks. A prerequisite for feature-based matching of distinct points is the application of interest operators to provide the dense arrays of candidate feature points within the images forming the network. This paper describes an evaluation of three interest operators, the Förstner, SUSAN and FAST algorithms, the aim being to assess which is optimal for feature-based matching in convergent close range photogrammetry. Following a brief review of the development of interest operators, a description of the three operators is provided, with the recently developed FAST operator being discussed in more detail. The merits of image pre-processing via the Wallis filter are also outlined, after which the performance of the interest operators is experimentally assessed within an eight-image network on the basis of accuracy of interest-point localisation, detection rate and speed. The findings of the evaluation are that, of the Förstner, SUSAN and FAST operators, the FAST, which has not been employed to a significant extent in photogrammetry to date, is optimal for feature-based matching in multi-image close range networks. Copyright RS&PS + Blackwell Publishing Numéro de notice : A2010-061 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2009.00559.x En ligne : https://doi.org/10.1111/j.1477-9730.2009.00559.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30257 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
106-2010011	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Digital camera performance where spatial resolution is determined by the optical component / G.H. Thomson in Photogrammetric record, vol 25 n° 129 (March - May 2010)  

Public [article]  inPhotogrammetric record > vol 25 n° 129 (March - May 2010) . - pp 42 - 46 Titre : Digital camera performance where spatial resolution is determined by the optical component Type de document : Article/Communication Auteurs : G.H. Thomson, Auteur Année de publication : 2010 Article en page(s) : pp 42 - 46 Note générale : Bibliographie 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] capteur spatial [Termes IGN] diffraction [Termes IGN] pouvoir de résolution géométrique [Termes IGN] système optique [Termes IGN] test de performance Résumé : (Auteur) The spatial resolution attributed to digital cameras is usually based on the number or size of the pixels in the sensor. On closer examination it can often be shown that the real limit to the level of detail recorded by a camera will in practice be due to the performance of the optical system. An example of how this happens is given with a comparison between two satellite camera systems. Copyright RS&PS + Blackwell Publishing Numéro de notice : A2010-062 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2009.00566.x Date de publication en ligne : 11/03/2010 En ligne : https://doi.org/10.1111/j.1477-9730.2009.00566.x Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30258 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
106-2010011	RAB	Revue	Centre de documentation	En réserve L003	Disponible