Centre de documentation
scientifique

Dépouillements

Urban tree cover mapping with relief-corrected aerial imagery and lidar / B. Lehrbass in Photogrammetric Engineering & Remote Sensing, PERS, vol 78 n° 5 (May 2012)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 78 n° 5 (May 2012) . - pp 473 - 484 Titre : Urban tree cover mapping with relief-corrected aerial imagery and lidar Type de document : Article/Communication Auteurs : B. Lehrbass, Auteur ; Jing Wang, Auteur Année de publication : 2012 Article en page(s) : pp 473 - 484 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] arbre (flore) [Termes IGN] arbre urbain [Termes IGN] carte de la végétation [Termes IGN] classification orientée objet [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] flore urbaine [Termes IGN] fusion d'images [Termes IGN] image aérienne [Termes IGN] modèle numérique de surface [Termes IGN] Ontario (Canada) [Termes IGN] orthoimage [Termes IGN] précision de la classification [Termes IGN] zone urbaine Résumé : (Auteur) Urban tree canopy cover is often mapped by classifying high-resolution multispectral imagery. However, it can be difficult to differentiate low-lying vegetation from tree cover using optical data alone. Combining a lidar-derived Normalized Digital Surface Model (ndsm) improves classification accuracy, but the optical imagery is often imperfectly aligned with the NDSM. Aerial imagery is normally orthorectified using the ground elevation. However, tall objects in the orthorectified imagery still suffer from relief displacement. This can cause classification errors when lidar and the aerial imagery are combined. This study presents an approach for urban tree cover mapping composed of two parts: a method for correcting the relief displacement of trees in previously orthorectified aerial imagery, and an object-based classification method which combines relief-corrected multispectral aerial imagery with a lidar-derived NDSM. Using these methods, the tree cover was mapped for a 1,600 ha region of London, Ontario, Canada with improved positional and classification accuracy. Numéro de notice : A2012-233 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.14358/PERS.78.5.473 En ligne : https://doi.org/10.14358/PERS.78.5.473 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31679 [article]

Estimating urban leaf area index (LAI) of individual trees with hyperspectral data / R. Jensen in Photogrammetric Engineering & Remote Sensing, PERS, vol 78 n° 5 (May 2012)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 78 n° 5 (May 2012) . - pp 495 - 504 Titre : Estimating urban leaf area index (LAI) of individual trees with hyperspectral data Type de document : Article/Communication Auteurs : R. Jensen, Auteur ; P. Hardin, Auteur ; A. Hardin, Auteur Année de publication : 2012 Article en page(s) : pp 495 - 504 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] analyse spectrale [Termes IGN] arbre (flore) [Termes IGN] feuillu [Termes IGN] image hyperspectrale [Termes IGN] Leaf Area Index [Termes IGN] réflectance végétale [Termes IGN] Utah (Etas-Unis) [Termes IGN] zone urbaine Résumé : (Auteur) This study estimated leaf area index (LAI) of individual urban trees as a function of spectral features derived from airborne hyperspectral data. Candidate features included spectral indexes, principal components, and calibrated reflectance values. Hyperspectral images were acquired over Provo, Utah area, and LAI of 204 deciduous trees was measured in the field. These tree canopies were identified on the images, and spectral features were extracted using both whole canopy and mean-lit spectra techniques. Multiple regression and artificial neural networks were used to model leaf area and determine which spectral features were most strongly related to it. Results established that simple hyperspectral vegetation indexes explained more variation in urban tree LAI than either principal component scores or simple band reflectance values. The neural network model trained with a subset of those indexes explained more variation in LAI (R2 = 64.8 percent) than any of the multiple regression models tested. Numéro de notice : A2012-234 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.14358/PERS.78.5.495 En ligne : https://doi.org/10.14358/PERS.78.5.495 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31680 [article]

Photogrammetric monitoring of the construction of a solar energy dish concentrator / M. Shortis in Photogrammetric Engineering & Remote Sensing, PERS, vol 78 n° 5 (May 2012)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 78 n° 5 (May 2012) . - pp 519 - 527 Titre : Photogrammetric monitoring of the construction of a solar energy dish concentrator Type de document : Article/Communication Auteurs : M. Shortis, Auteur ; G. Burgess, Auteur Année de publication : 2012 Article en page(s) : pp 519 - 527 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie terrestre [Termes IGN] photogrammétrie terrestre [Termes IGN] surveillance d'ouvrage Résumé : (Auteur) Close-range photogrammetry has been used to control the construction of a jig used in the assembly of a new genera-tion solar concentrator and the validation of the final, mirrored surface. The concentrator is a concave paraboloid dish with an area of a 489 m2. The typical photogrammetric relative precision realized was 1:175,000, corresponding to an accuracy of better than 1 mm at the jig reference points. The validation of the mirrored surface achieved a relative precision of 1:300,000. Photogrammetry was also used to characterize the dish mirror panels. The rear surface of the panels was mapped, as it made possible a denser target array and quicker image capture than if the reflective surface was used. The targets were produced with a digital projector, and the typical measurement precision attained was 1:150,000. This paper describes the equipment and techniques required to provide the required accuracy and precision for the jig and panel surfaces. Numéro de notice : A2012-235 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.78.5.519 En ligne : https://doi.org/10.14358/PERS.78.5.519 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31681 [article]