Wyniki wyszukiwania - BazTech

1

Enhancement of inverse-distance-weighting 2D interpolation using accelerated decline

Ruffhead Andrew Carey

Reports on Geodesy and Geoinformatics

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2023

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Vol. 116

9--14

EN

Two-dimensional interpolation - or surface fitting - is an approximation tool with applications in geodetic datum transformations, terrain modelling and geoid determination. It can also be applied to many other forms of geographic point data, including rainfall, chemical concentrations and noise levels. The problem of fitting of a smooth continuous interpolant to a bivariate function is particularly difficult if the dataset of control points is scattered irregularly. A typical approach is a weighted sum of data values where the sum of the weights is always unity. Weighting by inverse distance to a power is one approach, although a power greater than 1 is needed to ensure smooth results. One advantage over other methods is that data values can be incorporated into the interpolated surface. One disadvantage is the influence of distant points. A simple cut-off limit on distance would affect continuity. This study proposes a transition range of accelerated decline by means of an adjoining polynomial. This preserves smoothness and continuity in the interpolating surface. Case studies indicate accuracy advantages over standard versions of inverse-distance weighting.

2

The application of least-squares method for approximating the surfaces of engineering structures

Lenda G.

Geomatics and Environmental Engineering

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2008

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Vol. 2, no. 1

49-57

EN

The report is focused on the presentation of current methods allowing for the approximation of point sets by means of ideal mathematical surfaces, as well as on the analysis of their suitability depending on the type of the object approximated and the complexity of the methods. The advantages and disadvantages of these methods have been compared with the capabilities offered by splines. Also, the application of the various variants of LSM have been discussed with reference to the minimization of the algebraic distance, the distance directed along a specific axis of the coordinate system and the geometrical distance. Finally, cases where the application of particular methods is justified with respect to accuracy and cost-effectiveness have been analyzed.

PL

Opracowanie skupia się na przedstawieniu aktualnych metod pozwalających na aproksymację zbiorów punktowych za pomocą idealnych powierzchni matematycznych, jak również na analizie ich przydatności, w zależności od rodzaju przybliżanego obiektu i skomplikowania metody. Zestawiono wady i zalety tych metod z możliwościami, które oferują funkcje sklejane. Następnie przybliżono zastosowanie różnych wariantów metody najmniejszych kwadratów w odniesieniu do minimalizacji odległości algebraicznej, odległości ukierunkowanej wzdłuż konkretnej osi układu współrzędnych oraz odległości geometrycznej. Przeanalizowano również, w jakich przypadkach zastosowanie poszczególnych metod ma uzasadnienie dokładnościowe i ekonomiczne.

3

Modelling and the inverse problem in spectrally resolved thermoluminescence

Mandowski A., Mandowska E., Świątek J.

Prace Naukowe. Chemia / Wyższa Szkoła Pedagogiczna w Częstochowie

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2003

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Vol. 8

37--44

EN

Typical analysis of thermoluminescence (TL) is based on various curve fitting algorithms. Older methods used merely several characteristic points of TL curves as the peak position, inflection points or peak width. This approach is generally not suitable for advanced TL measurements utilizing simultaneous detection of wavelength and intensity of the emitted light. In this paper we present some numerical methods for modelling (simulation) of spectrally resolved thermoluminescence as well as determination of parameters of traps and recombination centres from measured data. The latter case is more complex. For this purpose we put forward a new technique called surface fitting. Exemplary data for selected materials are presented.

4

Estimating wound volumes from scanner data

Martin R. R., Anguh M. M.

Machine Graphics and Vision

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1998

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Vol. 7, No. 4

879-889

EN

This paper considers how data from combined 3D depth maps and colour images can be used to estimate the volume of a wound - a procedure which may be important to its successful treatment. The colour image is used to segment the data into wound and non-wound areas. We then use the area of good skion surrounding thye wound to fit a hypothetical surface going across the wound, telling us where the skin surface would have been without a wound. Finally, data in the wound area is used to estimate the depth of the wound relative to this hypothetical surface, from which the volume of the wound can be computed. The main new contribution of this paper lies in the surface fitting method described. At pesent only a methodology is given, as practical tests have not been carried out.