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A basis for estimating digital camera parameters / D. Light in Photogrammetric Engineering & Remote Sensing, PERS, vol 70 n° 3 (March 2004)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 70 n° 3 (March 2004) . - pp 297 - 300 Titre : A basis for estimating digital camera parameters Type de document : Article/Communication Auteurs : D. Light, Auteur Année de publication : 2004 Article en page(s) : pp 297 - 300 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] caméra numérique [Termes IGN] diffraction [Termes IGN] échantillonnage d'image [Termes IGN] pas d'échantillonnage au sol [Termes IGN] pixel Résumé : (Auteur) Matching the diffraction -limited optical resolution with the appropriate detector size is a fundamental design requirement for digital imaging systems. A useful Design Function based on the Airy disk is lF/p = 0.82. Where is the average wavelength, F is the camera F-number, and p is the detector sampling pitch (pixel size). A second metric, attributed to Schade and reported by Holst (1999), produces an often used Design Function: lF1p = 1. Examples demonstrate the use of the Design Functions to determine basic parameters, F-number, focal length, aperture diameter, and pixel size for an imaging system. Pixel size is selected from commercially available arrays and the other parameters are estimated given the required ground sampled distance (GSD) with either of the two Design Functions. One of the primary uses for the Design Functions is to provide optical systems engineers with a simple, fast, and proven means of arriving at first-order estimates -for electro-optical camera designs. It follows that estimating costs for building large space camera systems should be less complicated. Numéro de notice : A2004-102 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.70.3.297 En ligne : http://dx.doi.org/10.14358/PERS.70.3.297 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26629 [article]

Accuracy of airborne lidar derived elevation: empirical assessment and error budget / M.E. Hodgson in Photogrammetric Engineering & Remote Sensing, PERS, vol 70 n° 3 (March 2004)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 70 n° 3 (March 2004) . - pp 331 - 339 Titre : Accuracy of airborne lidar derived elevation: empirical assessment and error budget Type de document : Article/Communication Auteurs : M.E. Hodgson, Auteur ; P. Bresnahan, Auteur Année de publication : 2004 Article en page(s) : pp 331 - 339 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] altitude [Termes IGN] ALTM [Termes IGN] cartographie topographique [Termes IGN] données lidar [Termes IGN] GPS en mode statique [Termes IGN] précision géométrique (imagerie) [Termes IGN] utilisation du sol [Termes IGN] valeur efficace Résumé : (Auteur) As part of a countywide large-scale mapping effort for Richland County, South Carolina, an accuracy assessment of a recently acquired lidar-derived data set was conducted. Airborne lidar (2m nominal posting) was collected at a flying height of 1207 meters above ground level (AGL) using an Optech ALTM (Airborne Laser Terrain Mapper) 1210 system. Unique to this study are the reference point elevations. Rather than using an interpolation approach for gathering observed elevations at reference points, the x-y coordinates of lidar points were located in the field and these elevations were surveyed. Using both total-station-based and rapid-static GPS techniques, observed vertical heights were measured at each reference lidar posting. The variability of vertical accuracy was evaluated for six land-cover categories. Root-mean-squared error (RmsE) values ranged from a low of 17 to 19 cm (pavement, low grass, and evergreen forests) to a high of 26 cm (deciduous forests). The unique error assessment of lidar postings also allowed for the creation of an error budget model. The observed lidar elevation error was decomposed into errors from lidar system measurements, horizontal displacement, interpolation error, and surveyor error. A cross-validation approach was used to assess the observed interpolated lidar elevation error for each field-verified reference point. In order of decreasing importance, the lidar system measurements were the dominant source of error-followed by interpolation error, horizontal displacement error, and surveyor error. Observed elevation error in steeper slopes (e.g., 25°) was estimated to be twice as large as those on low slopes (e.g., 1.5°). Copyright ASPRS Numéro de notice : A2004-103 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.70.3.331 En ligne : https://doi.org/10.14358/PERS.70.3.331 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26630 [article]

Automating the analysis of remotely sensed data / C. Skelsey in Photogrammetric Engineering & Remote Sensing, PERS, vol 70 n° 3 (March 2004)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 70 n° 3 (March 2004) . - pp 341 - 350 Titre : Automating the analysis of remotely sensed data Type de document : Article/Communication Auteurs : C. Skelsey, Auteur ; A.N.R. Law, Auteur ; et al., Auteur Année de publication : 2004 Article en page(s) : pp 341 - 350 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] analyse de données [Termes IGN] automatisation [Termes IGN] mise à jour de base de données [Termes IGN] photo-interprétation [Termes IGN] système d'information environnementale Résumé : (Auteur) Land cover is a complex phenomenon, its appearance and transition influenced by the soil, topography, climate, politics, ecology, and other aspects of land use. An operational study of land-cover change must consider such factors, and, if automation is to be employed, a new approach to software architecture and reasoning is required. The Macaulay Institute has developed the concept of task orientation as a means of supporting such work, and is currently investigating its utility in the update of the Land Cover of Scotland (1988) dataset. This paper describes the motivation behind the development of ETORA-II, an operational toolkit providing a task-orientated capability, and SYMOLAC-II, a proof-of-concept application. The final aim of this work is to produce an environmental information system for Scotland's land cover. Numéro de notice : A2004-104 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.70.3.341 En ligne : https://doi.org/10.14358/PERS.70.3.341 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26631 [article]