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Improvement of an oak canopy model extracted from digital photogrammetry / P. Gong in Photogrammetric Engineering & Remote Sensing, PERS, vol 68 n° 9 (September 2002)
[article]
Titre : Improvement of an oak canopy model extracted from digital photogrammetry Type de document : Article/Communication Auteurs : P. Gong, Auteur ; X. Mei, Auteur ; S. Biging, Auteur ; Z. Zhang, Auteur Année de publication : 2002 Article en page(s) : pp 919 - 924 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image
[Termes IGN] couvert forestier
[Termes IGN] extraction du sursol
[Termes IGN] feuille (végétation)
[Termes IGN] interpolation
[Termes IGN] modèle numérique de surface
[Termes IGN] photogrammétrie numérique
[Termes IGN] Quercus (genre)
[Termes IGN] surveillance forestièreRésumé : (Auteur) Digital surface models (DSMs) automatically derived with digital photogrammetric systems are useful in land surface change monitoring, including forest growth monitoring. However, they cannot be applied directly to forest canopy change analysis with high accuracy due to the inevitable deficiencies in existing commercial digital photogrammetry packages. In a hardwood rangeland monitoring study, we found that the oak tree and woodland canopy boundaries were not well determined using several digital photogrammetry packages available to us. There was a noticeable discrepancy between the true crown closure and that determined by subtracting the DSM and the corresponding DEM that excludes tree heights. In this paper, we present a correction method for improvement at the erroneous canopy boundary locations in the DSM using shadow and boundary information extracted from imagery. The method is designed for correcting errors for broadleaf tree canopies. Aerial photographs taken over oak woodland hills were tested. Using manual photogrammetric measurements as the reference, we found that most of the points (88.3 percent) on the canopy boundaries were displaced by greater than 1 meter with a conventional digital photogrammetric package. After the proposed algorithms were applied, greater than 98.6 percent of the points on canopy boundaries were found to be within 1 meter of their reference positions. 78.4 percent of the reference points had greater than 2 meters elevation errors with the conventional package while greater than 85.6 percent of those points were found to be within 2 meters of the reference after the proposed algorithms were applied. Numéro de notice : A2002-184 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : sans En ligne : https://www.asprs.org/wp-content/uploads/pers/2002journal/september/2002_sep_919 [...] Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22099
in Photogrammetric Engineering & Remote Sensing, PERS > vol 68 n° 9 (September 2002) . - pp 919 - 924[article]Artificial neural networks as a method of spatial interpolation for digital elevation models / D.A. Merwin in Cartography and Geographic Information Science, vol 29 n° 2 (April 2002)
[article]
Titre : Artificial neural networks as a method of spatial interpolation for digital elevation models Type de document : Article/Communication Auteurs : D.A. Merwin, Auteur ; R.G. Cromley, Auteur ; Daniel L. Civco, Auteur Année de publication : 2002 Article en page(s) : pp 99 - 110 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes d'information géographique
[Termes IGN] interpolation inversement proportionnelle à la distance
[Termes IGN] interpolation spatiale
[Termes IGN] modèle numérique de surface
[Termes IGN] réseau neuronal artificiel
[Termes IGN] valeur efficaceRésumé : (Auteur) This paper examines the performance of artificial neural networks (ANNs) as a method of spatial interpolation, when presented with irregular and regular samples of elevation data. The results of the ANN interpolation are compared with results obtained by kriging. Tests of spatial bias in the systematic errors contained in each of the neural network-derived DEMs were conducted using four attributes: slope, aspect, average direction and average distance from the nearest sampled value. Based on RMS and other evaluation measures, the accuracy of estimated DEMs from regular and irregular sample distributions using neural networks is lower than the accuracy level derived from kriging. The accuracy level of the ANN interpolators also decreases as the range of elevation values in DEMs increases. As reported in the literature, ANNs are approximate interpolators, and the pattern of under-prediction and over-prediction of elevation values in this study revealed that all estimated values fell within the range of sample elevations. Neural networks cannot predict values outside the range of elevation values contained in the sample, a property shared by other interpolators such as inverse weighted distance. Numéro de notice : A2002-144 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/INFORMATIQUE Nature : Article DOI : 10.1559/152304002782053323 En ligne : https://doi.org/10.1559/152304002782053323 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22059
in Cartography and Geographic Information Science > vol 29 n° 2 (April 2002) . - pp 99 - 110[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 032-02021 RAB Revue Centre de documentation En réserve L003 Disponible Preserving cartographic quality in DTM interpolation from contour lines / Gil Rito-Gonçalves in ISPRS Journal of photogrammetry and remote sensing, vol 56 n° 3 (April - June 2002)
[article]
Titre : Preserving cartographic quality in DTM interpolation from contour lines Type de document : Article/Communication Auteurs : Gil Rito-Gonçalves , Auteur ; Patrick Julien , Auteur ; S. Razanioff, Auteur ; Bernard Cervelle, Auteur Année de publication : 2002 Article en page(s) : pp 210 - 220 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image
[Termes IGN] contour
[Termes IGN] courbe de niveau
[Termes IGN] diagramme de Voronoï
[Termes IGN] interpolation
[Termes IGN] modèle numérique de terrain
[Termes IGN] orographie
[Termes IGN] qualité cartographique
[Termes IGN] triangulation de DelaunayRésumé : (Auteur) Fitting an elastic grid to contour lines (CLs) produces a surface with tighter intermediate contours than the initial ones. This leads to intermediate contours that do not match the initial ones. In this paper, we propose a method for correcting this defect, by fitting the elastic grid to supplementary constraint lines that correspond approximately to the terrain morphologic lines (ridges and drainages). We extract these lines from a Delaunay triangulation consistent with the contour lines. We propose a coherent weighting system for the constraints imposed on the elastic grid. Finally, we show that a digital terrain model (DTM) artefact of the type mentioned above can be detected by a simple criterion such as the contour length. Copyright ISPRS Numéro de notice : A2002-095 Affiliation des auteurs : MATIS+Ext (1993-2011) Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/S0924-2716(02)00044-8 En ligne : https://doi.org/10.1016/S0924-2716(02)00044-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22010
in ISPRS Journal of photogrammetry and remote sensing > vol 56 n° 3 (April - June 2002) . - pp 210 - 220[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 081-02011 SL Revue Centre de documentation Revues en salle Disponible The interpolation problem in GPS-supported aerial triangulation / Derek D. Lichti in Photogrammetric record, vol 17 n° 99 (April - September 2002)
[article]
Titre : The interpolation problem in GPS-supported aerial triangulation Type de document : Article/Communication Auteurs : Derek D. Lichti, Auteur Année de publication : 2002 Article en page(s) : pp 481 - 492 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie spatiale
[Termes IGN] aérotriangulation analytique
[Termes IGN] compensation par faisceaux
[Termes IGN] Global Positioning System
[Termes IGN] interpolationRésumé : (Auteur) On fournit dans cet article les résultats d'une étude portant sur l'influence de différents modèles et faux d'échantillonnage dans l'interpolation des coordonnées des centres perspectifs dans une aérotriangulation assistée par GPS. On a mis en oeuvre des modèles standards du commerce et unfiltrage rigoureux dans la reconstruction du signal dans une aérotriangulation par blocs de clichés à grande échelle. C'est le taux d'échantillonnage GPS que l'on a trouvé comme ayant le plus d'influence sur les résultats de la compensation par faisceaux en ce qui concerne les résidus des centres perspectifs. Toutefois la précision obtenue sur les coordonnées des points dans l'espaceobjet est apparue insensible à la fois au taux d'échantillonnage GPS et à la méthode d'interpolation. Numéro de notice : A2002-084 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/0031-868X.00200 En ligne : https://doi.org/10.1111/0031-868X.00200 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=21999
in Photogrammetric record > vol 17 n° 99 (April - September 2002) . - pp 481 - 492[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 106-02011 RAB Revue Centre de documentation En réserve L003 Disponible
Titre : 3D terrain models on the basis of a triangulation Type de document : Thèse/HDR Auteurs : Norbert Pfeifer, Auteur Editeur : Vienne [Autriche] : Technische Universität Wien Année de publication : 2002 Collection : Geowissenschaftliche Mitteilungen, ISSN 1811-8380 num. 65 Importance : 142 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-9500791-7-3 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique
[Termes IGN] données localisées 3D
[Termes IGN] interpolation
[Termes IGN] modèle numérique de terrain
[Termes IGN] noeud
[Termes IGN] reconstruction 3D
[Termes IGN] triangulation de DelaunayRésumé : (Auteur) This work provides an overview on terrain modelling techniques. Terrain models, or in order to be more general, topographic surface models, play an important role in many fields of science and practice where a relation to a location, i.e. a geo-relation' is given. These models describe the height as a function of the location. There lies a restriction in this definition, because only one height is allowed at one ground-plane position. Therefore, the currently used models are often termed 2.5D terrain models. The modelling of overhangs is not possible within such an approach. The aim of this work is to put aside this limitation and provide methods for 3D terrain modelling where not only the above restrictions do not apply anymore, but also more general surfaces with tunnels and cave systems can be reconstructed. Another terrain property which plays an important role in this work is its smoothness: a model shall be smooth. An exception is introduced at so-called breaklines where the terrain shape has a sharp edge.
There are several ways in order to build terrain models with the above characteristics (fully 3D and smooth). In this work, emphasis is put on those approaches which reconstruct the surface on the basis of a triangulation. Two different techniques are treated with great detail: the patch work and the subdivision approach. For each of those two, one method was developed which considers the special requirements in terrain modelling. The main contribution of this work to terrain modelling are those new methods. Generation, improvement, and thinning of triangulations is not treated within this work, but references to the relevant literature are given. Generally, the reconstruction of a patch work proceeds as follows. Given is a triangulation, which has as expected planar faces. For each edge a curve is determined which interpolates the end points. In the next step, triangular patches are inserted into a triple of boundary curves spanned over the edges of each triangle. As the patches interpolate the boundary curve a G0 surface (a geometrically continuous surface) is obtained.
However, this is not enough, because a smooth surface (G1, geometric continuity of order one, i.e. tangent plane continuity) is desired. Adjacent patches must therefore interpolate not only the boundary curves, but also share a common field of cross boundary derivatives. This is the general approach for patch work surfaces.
The patch work method which is proposed in this work1 starts with an enhancement of the triangulation. As the measurement of terrain points and lines is always burdened with random errors (depending on the measurement device characteristics) these errors should be removed first. This can be achieved by kriging, whereby for each point of the triangulation (i.e. each vertex) a filter value is determined from its neighboring points. In this step also the surface normal vectors in the points can be estimated, but alternative methods for the estimation of the normal vector, e.g. by averaging those of the triangles which are incident to that vertex, are possible, too. Now, not only the position, but also the surface normal vector is prescribed for each vertex. The patches which are to be reconstructed over each face of the triangulation shall be polynomials of degree four and they are described with Beziér triangles which allow a geometric interpretation of the coefficients of the (bivariate) polynomial. In the next step, boundary curves of polynomial degree three are computed which replace' the edges of the triangulation. These curves interpolate the end points of the edge and the curve tangents in those points are perpendicular to the estimated normal vectors. This determines the boundaries of each patch. The missing parameters (i.e. coefficients of the polynomial) influence the shape in the interior of the patch and also the tangent planes of the patch along the boundaries. A field of normal vectors is estimated for each boundary curve by blending the normal vectors from the end points into each other. The inner' parameters of a patch are now determined in a way that the normal vector fields are approximately perpendicular to the tangent planes of the patch along the boundaries in a least squares sense. As this field is only' approximated and not interpolated this scheme is called "G1 (i.e. approximately tangent plane continuous).
The second technique for surface reconstruction over a triangulation is the so-called subdivision. In this approach the given triangulation is refined in steps, and in each step new vertices and edges are inserted into the triangulation. This is performed in a way that the smoothness of the triangulation is increased in each level, the angles between adjacent triangles converge towards 180_. The limit surface, reached after an infinite number of subdivision steps, is smooth. An advantage of this approach is that the surface description is always composed of small triangles which allows to apply simple algorithms for intersections and similar tasks. The size of the triangles depends on the number of subdivision steps (i.e. the refinement level). This is the general approach for subdivision surfaces.
Also in the reconstruction technique (developed in this work) for topographic surfaces which is based on subdivision a removal of random measurement errors has to be performed first. The refinement rule applied here is the so-called edge midpoint subdivision where in one step one vertex is inserted into each edge and the triangulation is updated. The subdivision is based on the estimation of local surfaces in each vertex. A local surface is estimated which approximates the vertex of interest and its neighbors. The co-ordinates of the new points are obtained by averaging the two local surfaces in either edge end point. To achieve this, a point, representative for the edge midpoint, is computed on both local surfaces and the mean of these two is the new point. Also the old' points obtain new co-ordinates, namely their position on the local approximating surfaces. Special modifications are introduced in order to interpolate the originally given points. The approaches are compared to each other with examples based on real photogrammetric and geodetic observations as well as on synthetic terrain data. It turns out that the surfaces obtained by the developed subdivision approach meet the requirements in topographic terrain modelling better.Note de contenu : 1 Introduction
2 Modelling of Topographic Surfaces
2.1 Types of Models
2.1.1 Contour lines
2.1.2 Bivariate functions
2.1.3 Volumetric models
2.1.4 Transformation between models
2.2 Global and local approaches
2.3 Models in 2.5D and in 3D
2.4 3D terrain models
2.4.1 Problem definition
3 Algorithms for Triangulations
3.1 Definition of neighborhood
3.2 Parameterization of triangulations
3.2.1 Projection onto a plane
3.2.2 Local projection onto a plane
3.2.3 Global parameterizations
3.2.4 A method for local parameterization
3.3 Surface approximation and estimation of geometric properties
3.3.1 Normal vectors and tangent planes
3.3.2 Approximating quadric as local surface description
3.3.3 Approximating second order polynomial as local surface description
3.4 Functionals and variational principle
3.5 Mesh improvement
3.6 Filtering of random measurement errors
3.7 Consideration of breaklines and special points
3.7.1 Neighborhood restrictions
3.7.2 Prescribed tangent planes
3.7.3 Surfaces and lines at special points
4 Parametric patches
4.1 Patches and patch work
4.2 Method overview
4.3 An "G1-continuous polynomial patch
4.3.1 Approximate continuity
4.3.2 Construction of a curve network
4.3.3 Insertion of patches
4.3.4 Insertion of patches and minimizing energy
4.3.5 Additional splitting
4.3.6 Results
5 Subdivision
5.1 The subdivision paradigm
5.2 Method overview
5.3 Subdivision by estimation of local surfaces
5.3.1 The curve case
5.3.2 Surface subdivision with approximating surfaces
5.3.3 Paraboloids vs. general quadrics as local surfaces
5.3.4 Paraboloids vs. second order polynomials as local surfaces
5.3.5 Interpolation and Approximation
5.3.6 Averaging
5.3.7 Roughness detection
5.3.8 Results
6 Examples
6.1 Vertical Wall
6.2 Data set “Elev”
6.3 Breaklines only
6.4 Data set “Albis”
6.5 Bridge
7 Conclusions and Perspectives
7.1 Applications
7.2 Enclaves
7.3 Concluding remarkNuméro de notice : 14314 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Thèse étrangère Note de thèse : PhD : Vermessung und Geoinformation : Technische Universität Wien : 2002 En ligne : https://repositum.tuwien.at/handle/20.500.12708/390?mode=simple Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=62656 Aufbau der neuen Landesvermessung der Schweiz 'LV95'. Teil 10, Das Geoid der Schweiz 1998 "CHGEO98" / Urs Marti (2002)PermalinkPermalinkIntegrating spatial data analysis and GIS: a new implementation using the Component Object Model (COM) / M.J. Ungerer in International journal of geographical information science IJGIS, vol 16 n° 1 (january 2002)PermalinkDigital terrain models / W. Lu in GIM international, vol 15 n° 12 (December 2001)PermalinkAn approach to single image automatic orientation and point determination by using ortho-images and a DTM / J.S. Shan in Photogrammetric record, vol 17 n° 98 (October 2001 - March 2002)PermalinkOn the uncertainty of local shape of lines and surfaces / B. Schneider in Cartography and Geographic Information Science, vol 28 n° 4 (October 2001)PermalinkArtificial neural networks as a tool for spatial interpolation / J.P. Rigol in International journal of geographical information science IJGIS, vol 15 n° 4 (june 2001)PermalinkDasymetric mapping and areal interpolation: implementation and evaluation / C.L. Eicher in Cartography and Geographic Information Science, vol 28 n° 2 (April 2001)PermalinkAccuracy of the Canadian digital terrain data in the Gatineau Region of Quebec / Rob Reeves in Geomatica, vol 55 n° 1 (March 2001)PermalinkAn overview of multi-reference station methods for cm-level positioning / Georgia Fotopoulos in GPS solutions, vol 4 n° 3 (January 2001)PermalinkDreidimensionale kinematische Modelle zur Analyse von Deformationen an Hängen / P. Rawiel (2001)PermalinkEvaluation de la qualité d'une cartographie urbaine à l'aide d'images aériennes à haute résolution / Olivier de Joinville (2001)PermalinkEstimation et interpolation spatiale / Michel Arnaud (2000)PermalinkGeomatic methods for the analysis of data in the Earth sciences / Athanasios Dermanis (2000)PermalinkPlate-forme pour traitement d'images RSO complexes / Allal Guesmia (2000)PermalinkInterpolation et filtrage des données laser scanner en zone boisée / D. Desbuisson in XYZ, n° 79 (juin - août 1999)PermalinkSpatio-temporal interpolation and fuzzy logic for GIS simulation of rural-to-urban transition / Suzana Dragićević in Cartography and Geographic Information Science, vol 26 n° 2 (April 1999)PermalinkConstitution d'orthophotos à partir de plusieurs images aériennes à haute résolution / O. Randriamoramanana (1999)PermalinkPermalinkGeographical Information Systems, 1. Principles and technical issues / Paul A. Longley (1999)Permalink