Kagadal They are defined as the height difference between the highest and lowest pixel in the image. All six parameters are defined from the surface bearing area ratio curve shown in the figures below. This parameter is only meaningful if there is a ani direction on the sample. The Reduced Summit Height, Spkis the height of the upper left triangle. As there are no pixels outside the borders of the image there are no local minimums or local maximums on the borders. The Ansk WavelengthSrwis the dominating wavelength found in the radial spectrum.
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Tokinos Before the calculation of the roughness parameters we recommend carrying out a slope correction by a 2 nd or 3 rd order polynomial plane fit. The first parameter is calculated directly from the image, while the remaining are based on the Fourier spectrum. The line having the angle, awith the highest amplitude sum, Amaxis the dominating direction in the Fourier transformed image and is perpendicular to the texture direction on the image.
For a surface with a dominant lay, the parameters will tend towards 0. The Mean Half Wavelength, Shwis based on the integrated radial spectrum:. We calculate Std from the Fourier spectrum. The Reduced Summit Height, Spkis the height of the upper left triangle.
Three parameters are calculated based on this figure. Roughness Parameters Fourier spectrum and the angular and radial spectra. The hybrid parameters can be described graphically by the above figure. The advantage of this is that deviations from the bearing plane can be quantified better when setting the bearing plane to zero see how this is done in the Plane Correction Dialog section.
The Cross Hatch AngleSch is the found angle of a cross hatch pattern typically created in b As there are no pixels outside the borders of the image there are no local minimums or local maximums on the borders. The amplitude sum, A aat a line with the angle, ais defined as:. In principle, the texture aspect ratio has a value between 0 and 1. The amplitude properties are described by six parameters, which give information about the statistical average properties, the shape of the height distribution histogram and about extreme properties.
For an anisotropic surface the correlation length is in the direction perpendicular to the surface lay. The Surface Skewness, S skdescribes the asymmetry of the height distribution histogram, and is defined as:. For a Gaussian height distribution S bi approaches 0. With this definition Srwi is always between 0 and 1. This may be the case for image containing well organized linear structures.
The Density of SummitsSdsis the number of local maximums per area:. When there are less than five valid maximums or five valid minimums, the parameter is not defined. Smaller values indicate broader height distributions and visa versa for values greater than 3. Root Mean Square Gradient. These lines are marked Z 0. For these parameters we require the images to be quadratic.
The fractal dimension can also be evaluated from 2D Fourier spectra by application of the Log Log function. Dominant Radial Wave Length. For all surfaces S ci is between 0 and 0. Maximum Peak Height Sp: All the parameters are based on two-dimensional standards that anis extended to three dimensions. Note, amsi that roughness values depends strongly on measurement conditions especially scan range and sample density. Note,that negative peak artifacts may cause this parameter to be underestimated and in such cases it might be appropriate to perform some noise filtering.
These parameters are the density of summits, the texture direction, the dominating wavelength and two index parameters. The Texture Direction IndexStdiis a measure of how dominant the dominating direction is, and is defined as the average amplitude sum divided by the amplitude sum of the dominating direction:.
The Surfaces Area Ratio, S drexpresses the increment of the interfacial surface area relative to the area of the projected flat x,y plane:. This parameter is only meaningful if there is a dominating direction on the sample. The result is called the angular spectrum. If there is a very dominating wavelength, Srwi is close to 0, and if there is no v With this definition the Stdi value is always between 0 and 1.
The surface bearing area asni curve, which is also called the Abbott curve, is calculated by accumulation of the height distribution histogram and subsequent inversion. Related Posts
Surface Texture (Surface Roughness, Waviness, and Lay)