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Spectroscopic analysis of green, desiccated and dead tamarisk canopies / Ran Meng in Photogrammetric Engineering & Remote Sensing, PERS, vol 81 n° 3 (March 2015)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 81 n° 3 (March 2015) . - pp 199 - 207 Titre : Spectroscopic analysis of green, desiccated and dead tamarisk canopies Type de document : Article/Communication Auteurs : Ran Meng, Auteur ; Philip E. Dennison, Auteur Année de publication : 2015 Article en page(s) : pp 199 - 207 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] bande infrarouge [Termes IGN] bande rouge [Termes IGN] bande spectrale [Termes IGN] insecte nuisible [Termes IGN] rayonnement proche infrarouge [Termes IGN] réflectance végétale [Termes IGN] risque naturel [Termes IGN] Tamarix (genre) Résumé : (auteur) Defoliation by the northern tamarisk beetle (Diorhabda carinulata) causes changes in the reflectance of tamarisk (Tamarix spp.) canopies. Cross correlogram spectral matching was used to examine spectral separability of green, yellow desiccated, brown desiccated, and dead tamarisk canopy types. Using a feature selection technique (the instability index), four spectral regions were identified as important for canopy type discrimination, including one red (645-693 nm), one near infrared (735-946 nm), and two shortwave infrared regions (1,960-2,090 nm and 2,400-2,478 nm). The random forests decision tree algorithm was used to compare classification performances of full-range and feature-selected hyperspectral spectra as well as simulated WorldView-2 spectra. Classification results indicated that the process of feature selection can reduce data redundancy and computation time while improving accuracy of tamarisk canopy type classification. Numéro de notice : A2015-969 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.14358/PERS.81.3.199-207 En ligne : https://doi.org/10.14358/PERS.81.3.199-207 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80027 [article]

Quaternion-based solutions for the single photo resection problem / Mehdi Mazaheri in Photogrammetric Engineering & Remote Sensing, PERS, vol 81 n° 3 (March 2015)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 81 n° 3 (March 2015) . - pp 209 - 217 Titre : Quaternion-based solutions for the single photo resection problem Type de document : Article/Communication Auteurs : Mehdi Mazaheri, Auteur ; Ayman Habib, Auteur Année de publication : 2015 Article en page(s) : pp 209 - 217 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] matrice de rotation [Termes IGN] photographie isolée [Termes IGN] quaternion [Termes IGN] relèvement photogrammétrique [Termes IGN] transformation linéaire directe Résumé : (auteur) This paper introduces three quaternion-based approaches to solve the SPR problem. The first two are based on projective transformation and DLT coefficients through which the position of the perspective center is derived first using four or more planar and six or more non-planar object points, respectively. The rotation matrix is then directly estimated using quaternions. The third one (quaternion-based general approach) can handle three or more points in either planar or non-planar configuration. In this approach, the rotation angles are iteratively estimated first using quaternions without the need for user-defined approximations. Then, the position of the perspective center is directly derived. Experimental results show the feasibility of the proposed approaches and the high accuracy of the quaternion-based general approach, which is superior to the state-of-the-art non-iterative method and does not deviate more than 1 percent from the traditional non-linear SPR, i.e., the de-facto standard for the most accurate SPR solution. Numéro de notice : A2015-970 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.81.3.209-217 En ligne : https://doi.org/10.14358/PERS.81.3.209-217 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80028 [article]

Accuracy analysis of a dual camera system with an asymmetric photogrammetric configuration / Bo Wu in Photogrammetric Engineering & Remote Sensing, PERS, vol 81 n° 3 (March 2015)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 81 n° 3 (March 2015) . - pp 219 - 228 Titre : Accuracy analysis of a dual camera system with an asymmetric photogrammetric configuration Type de document : Article/Communication Auteurs : Bo Wu, Auteur ; Lei Ye, Auteur ; Yuansheng Yang, Auteur Année de publication : 2015 Article en page(s) : pp 219 - 228 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] caméra de surveillance PTZ [Termes IGN] caméra numérique [Termes IGN] image multi sources [Termes IGN] modèle géométrique de prise de vue [Termes IGN] objectif grand angulaire [Termes IGN] précision des mesures Résumé : (auteur) This paper presents a dual camera system combining a wide field-of-view (FOV) surveillance camera and a pan-tiltzoom (PTZ) camera with an asymmetric photogrammetric configuration, and focuses on the analysis of its attainable measurement accuracy. First, we discuss the geometric modeling of the asymmetric photogrammetric configuration and analyze the accuracy of measurement based on error propagation for different baseline lengths, different focal lengths, and different pan angles of the PTZ camera. Second, we performed a comprehensive accuracy analysis based on Monte Carlo simulation, which incorporated artificial noise into the input data. Third, we conducted actual experiments in indoor and outdoor environments to verify the theoretical and simulation results. We found that the baseline length between the dual cameras was the main factor influencing measurement accuracy. Increase of the PTZ camera focal length could improve the measurement accuracy, but this trend was not significant when its focal length was relatively long. The pan angle of the PTZ camera also influenced the measurement accuracy, but this influence was not significant at short ranges. From these discoveries, we present an optimum configuration of the dual camera system for better than 1 percent measurement accuracy of the range within a normal observation range (e.g., 60 m). This proposed dual camera system provides enhanced machine vision capabilities that can be used in various applications. Numéro de notice : A2015-971 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.81.3.219-228 En ligne : http://dx.doi.org/10.14358/PERS.81.3.219-228 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80029 [article]