Two algorithms for constructing a Delaunay triangulation

Lee, D. T.; Schachter, Bruce J.

doi:10.1007/bf00977785

Cited by 1,256 publications

(619 citation statements)

References 19 publications

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“…This choice follows what was found by Foster & Evans (2008), that demonstrated how, in the case of local maps of TEC, the natural neighbour interpolation technique gives better results with respect to other commonly used methods (linear, inverse distance weighting, kriging, etc.). Details on the natural neighbour interpolation technique applied can be found in Okabe et al (1994) and Lee & Schachter (1980).…”

Section: Tec and Tec Spatial Gradientsmentioning

confidence: 99%

L-band scintillations and calibrated total electron content gradients over Brazil during the last solar maximum

Cesaroni

Spogli

Alfonsi

et al. 2015

J. Space Weather Space Clim.

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This work presents a contribution to the understanding of the ionospheric triggering of L-band scintillation in the region over São Paulo state in Brazil, under high solar activity. In particular, a climatological analysis of Global Navigation Satellite Systems (GNSS) data acquired in 2012 is presented to highlight the relationship between intensity and variability of the total electron content (TEC) gradients and the occurrence of ionospheric scintillation. The analysis is based on the GNSS data acquired by a dense distribution of receivers and exploits the integration of a dedicated TEC calibration technique into the Ground Based Scintillation Climatology (GBSC), previously developed at the Istituto Nazionale di Geofisica e Vulcanologia. Such integration enables representing the local ionospheric features through climatological maps of calibrated TEC and TEC gradients and of amplitude scintillation occurrence. The disentanglement of the contribution to the TEC variations due to zonal and meridional gradients conveys insight into the relation between the scintillation occurrence and the morphology of the TEC variability. The importance of the information provided by the TEC gradients variability and the role of the meridional TEC gradients in driving scintillation are critically described.

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Section: Tec and Tec Spatial Gradientsmentioning

confidence: 99%

L-band scintillations and calibrated total electron content gradients over Brazil during the last solar maximum

Cesaroni

Spogli

Alfonsi

et al. 2015

J. Space Weather Space Clim.

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show abstract

“…For the generation of the regular grid v(x, z), we first have to know in which triangle a particular gridpoint is located, and then to interpolate within this triangle. The efficient search of the encircling triangle is performed by the walking triangle or trifind algorithm (Lawson 1977;Lee & Schachter 1980;Sambridge et al 1995) without the need to check all triangles. The interpolation within a particular triangle is done by barycentric interpolation well known from computer graphics (e.g.…”

Section: O D E L Pa R a M E T R I Z At I O Nmentioning

confidence: 99%

Bayesian inversion of refraction seismic traveltime data

Ryberg

Haberland

2017

Geophysical Journal International

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S U M M A R YWe apply a Bayesian Markov chain Monte Carlo (McMC) formalism to the inversion of refraction seismic, traveltime data sets to derive 2-D velocity models below linear arrays (i.e. profiles) of sources and seismic receivers. Typical refraction data sets, especially when using the far-offset observations, are known as having experimental geometries which are very poor, highly ill-posed and far from being ideal. As a consequence, the structural resolution quickly degrades with depth. Conventional inversion techniques, based on regularization, potentially suffer from the choice of appropriate inversion parameters (i.e. number and distribution of cells, starting velocity models, damping and smoothing constraints, data noise level, etc.) and only local model space exploration. McMC techniques are used for exhaustive sampling of the model space without the need of prior knowledge (or assumptions) of inversion parameters, resulting in a large number of models fitting the observations. Statistical analysis of these models allows to derive an average (reference) solution and its standard deviation, thus providing uncertainty estimates of the inversion result. The highly non-linear character of the inversion problem, mainly caused by the experiment geometry, does not allow to derive a reference solution and error map by a simply averaging procedure. We present a modified averaging technique, which excludes parts of the prior distribution in the posterior values due to poor ray coverage, thus providing reliable estimates of inversion model properties even in those parts of the models. The model is discretized by a set of Voronoi polygons (with constant slowness cells) or a triangulated mesh (with interpolation within the triangles). Forward traveltime calculations are performed by a fast, finite-difference-based eikonal solver. The method is applied to a data set from a refraction seismic survey from Northern Namibia and compared to conventional tomography. An inversion test for a synthetic data set from a known model is also presented.

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“…Deformacije na površini stene smo izračunali iz razdalj med sosednimi točkami z enačbo (6). Sosednje točke smo prepoznali z Delaunayevo triangulacijo (Lee in Schachter, 1980), ki raztresene točke poveže v trikotniško nepravilno mrežo. Izračunani velikosti deformacije smo pripisali položaj sredine stranice, ki povezuje točki, iz katerih je bila deformacija izračunana.…”

Section: Opis Postopka Merjenja Deformacij Pri Preiskavah Mehanske Odunclassified

Photogrammetric measurement of deformations in tests of mechanical resistance of structural elements

Grigillo¹,

Snoj²,

Dolšek³

2016

geod. vestn.

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Two algorithms for constructing a Delaunay triangulation

Cited by 1,256 publications

References 19 publications

L-band scintillations and calibrated total electron content gradients over Brazil during the last solar maximum

L-band scintillations and calibrated total electron content gradients over Brazil during the last solar maximum

Bayesian inversion of refraction seismic traveltime data

Photogrammetric measurement of deformations in tests of mechanical resistance of structural elements

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