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Comprehensive GNSS solutions for international customers / M. Wang in GIM international, vol 26 n° 1 (January 2012)

Public [article]  inGIM international > vol 26 n° 1 (January 2012) . - pp 32 - 35 Titre : Comprehensive GNSS solutions for international customers Type de document : Article/Communication Auteurs : M. Wang, Auteur Année de publication : 2012 Article en page(s) : pp 32 - 35 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Infrastructure de données [Termes IGN] Chine [Termes IGN] données GNSS [Termes IGN] fournisseur [Termes IGN] marché de l'information géographique [Termes IGN] plateforme logicielle [Termes IGN] système d'information géographique Résumé : (Auteur) Founded on may 2001, KQ Geo Technologies CO., Ltd. is one of the few A-level surveying and mapping service providers qualified by the State Bureau of surveying and mapping in China. With over 800 employees and 25 regional offices throughout China, KQ has become one of the leading suppliers of GIS platforms, GNSS technologies and equipment, spatial data services, and GPS technologies. Numéro de notice : A2012-008 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31456 [article]

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Incremental segmentation of lidar point clouds with an octree-structured voxel space / M. Wang in Photogrammetric record, vol 26 n° 133 (March - May 2011)  

Public [article]  inPhotogrammetric record > vol 26 n° 133 (March - May 2011) . - pp 32 - 57 Titre : Incremental segmentation of lidar point clouds with an octree-structured voxel space Type de document : Article/Communication Auteurs : M. Wang, Auteur ; Yi-Hsing Tseng, Auteur Année de publication : 2011 Article en page(s) : pp 32 - 57 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] coplanarité [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] octree [Termes IGN] reconstruction d'objet [Termes IGN] segmentation [Termes IGN] semis de points [Termes IGN] voxel Résumé : (Auteur) Lidar (light detection and ranging) data implicitly contains abundant three-dimensional spatial information. The segmentation of lidar point clouds is the key procedure for transforming implicit spatial information into explicit spatial information. Common criteria used for point cloud segmentation are proximity and coherence of point distribution. An effective segmentation algorithm may apply various steps or combinations of criteria depending on the application. This paper proposes a four-step segmentation method for lidar point clouds to deliver incremental segmentation results. Segmentation results of each step can provide the fundamental data for the next step. In the first step, the input point cloud is organised into an octree-structured voxel space, in which the point neighbourhood is established. In the second step, connected voxels which are not empty are grouped to obtain grouped points based on proximity. The third step is a coplanar point segmentation based on both coherence and proximity, which was performed on each point group obtained in the second step. Finally, neighbouring coplanar point groups are merged into “co-surface” point groups based on the criteria of plane connection and intersection. This scheme enables an incremental retrieval and analysis of a large lidar data-set. Experimental results demonstrate the effectiveness of the segmentation algorithm in handling both airborne and terrestrial lidar data. It is anticipated that the incremental segmentation results will be useful for object modelling using lidar data. Numéro de notice : A2011-077 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2011.00624.x Date de publication en ligne : 16/03/2011 En ligne : https://doi.org/10.1111/j.1477-9730.2011.00624.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30858 [article]

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Epipolar arrangement of satellite imagery by projection trajectory simplification / M. Wang in Photogrammetric record, vol 25 n° 132 (December 2010 - February 2011)  

Public [article]  inPhotogrammetric record > vol 25 n° 132 (December 2010 - February 2011) . - pp 422 - 436 Titre : Epipolar arrangement of satellite imagery by projection trajectory simplification Type de document : Article/Communication Auteurs : M. Wang, Auteur ; F. Hu, Auteur ; J. Li, Auteur Année de publication : 2010 Article en page(s) : pp 422 - 436 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] courbe épipolaire [Termes IGN] image Ikonos [Termes IGN] image IRS [Termes IGN] image SPOT-HRG [Termes IGN] linéarisation [Termes IGN] lissage de courbe [Termes IGN] méthode des moindres carrés [Termes IGN] modèle stéréoscopique [Termes IGN] orbitographie [Termes IGN] parallaxe [Termes IGN] trajectoire (véhicule non spatial) Résumé : (Auteur) This paper presents an efficient algorithm for approximate epipolar image generation from stereoscopic satellite images by projection trajectory simplification. In this algorithm, the original non-linear projection trajectory is simplified to a linear one by the least squares line fitting of sample points selected from the projection trajectory. The performance of the algorithm is evaluated using IRS-P5, SPOT5-HRG and IKONOS stereo-images acquired in different stereoscopic imaging modes over different terrain types. The results obtained indicate that the vertical parallax of each pair of conjugate image points on the epipolar images thus generated achieves accuracy at the sub-pixel level. Numéro de notice : A2010-534 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2010.00602.x Date de publication en ligne : 22/12/2010 En ligne : https://doi.org/10.1111/j.1477-9730.2010.00602.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30726 [article]

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Automatic segmentation of Lidar data into coplanar point clusters using an octree-based split-and-merge algorithm / M. Wang in Photogrammetric Engineering & Remote Sensing, PERS, vol 76 n° 4 (April 2010)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 76 n° 4 (April 2010) . - pp 407 - 420 Titre : Automatic segmentation of Lidar data into coplanar point clusters using an octree-based split-and-merge algorithm Type de document : Article/Communication Auteurs : M. Wang, Auteur ; Yi-Hsing Tseng, Auteur Année de publication : 2010 Article en page(s) : pp 407 - 420 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] fusion d'images [Termes IGN] modélisation 3D [Termes IGN] octree [Termes IGN] segmentation [Termes IGN] segmentation en plan [Termes IGN] semis de points Résumé : (Auteur) Lidar (light detection and ranging) point cloud data contain abundant three-dimensional (3D) information. Dense distribution of scanned points on object surfaces prominently implies surface features. Particularly, plane features commonly appear in a typical lidar dataset of artificial structures. To explore implicitly contained spatial information, this study developed an automatic scheme to segment a lidar point cloud dataset into coplanar point clusters. The central mechanism of the proposed method is a split-and-merge segmentation based on an octree structure. Plane fitting serves as an engine in the mechanism that evaluates how well a group of points fits to a plane. Segmented coplanar points and derived parameters of their best-fit plane are obtained through the process. This paper also provides algorithms to derive various geometric properties of segmented coplanar points, including inherent properties of a plane, intersections of planes, and properties of point distribution on a plane. Several successful cases of handling airborne and terrestrial lidar data as well as a combination of the two are demonstrated. This method should improve the efficiency of object modelling using lidar data. Copyright ASPRS Numéro de notice : A2010-121 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.76.4.407 En ligne : https://doi.org/10.14358/PERS.76.4.407 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30317 [article]

Extrapolation of the aerosol reflectance from the near-infrared to the visible : the single-scattering epsilon vs multiple-scattering epsilon method / M. Wang in International Journal of Remote Sensing IJRS, vol 25 n° 18 (September 2004)  

Public [article]  inInternational Journal of Remote Sensing IJRS > vol 25 n° 18 (September 2004) . - pp 3637 - 3650 Titre : Extrapolation of the aerosol reflectance from the near-infrared to the visible : the single-scattering epsilon vs multiple-scattering epsilon method Type de document : Article/Communication Auteurs : M. Wang, Auteur Année de publication : 2004 Article en page(s) : pp 3637 - 3650 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] aérosol [Termes IGN] atmosphère terrestre [Termes IGN] bande visible [Termes IGN] correction atmosphérique [Termes IGN] correction d'image [Termes IGN] diffusion du rayonnement [Termes IGN] exitance spectrale [Termes IGN] image Seawifs [Termes IGN] radiance [Termes IGN] rayonnement proche infrarouge Résumé : (Auteur) In the atmospheric correction algorithm for Sea-viewing Wide Fieldof-view Sensor, the effects of the spectral variation of the aerosol radiance contributions at the two near-infrared (NIR) bands are estimated directly from sensor-measured radiance. The aerosol effects at the NIR are then extrapolated into, the visible through a process of aerosol model selection from evaluation of the NIR single-scattering epsilon value, which is defined as the ratio of the single-scattering aerosol reflectance between two NIR bands. The aerosol radiance contribution at the visible wavelengths is then removed. In this paper, a slightly different approach in the aerosol model selection and extrapolation, i.e. using the NIR multiple-scattering epsilon instead of the single-scattering epsilon, is examined. The NIR multiple-scattering epsilon is the ratio of the aerosol multiple-scattering reflectance between two NIR wavelengths. Simulations show that, in general, both methods give comparable results. Statistically, more than 95% of cases in the retrieved ocean colour spectrum are within required accuracy for both methods. For clear atmosphere, however, the results of the atmospheric correction using the single-scattering epsilon method usually performed slightly better than the multiple-scattering epsilon method. On the other hand, for the large aerosol optical thickness the multiple-scattering epsilon method has slightly better retrievals for the Tropospheric aerosols. Some detailed analyses and discussions are provided to explain differences in these two approaches for extrapolating and retrieving the aerosol effects in the visible. Numéro de notice : A2004-355 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01431160310001619599 En ligne : https://doi.org/10.1080/01431160310001619599 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26882 [article]

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