2D Advanced Surface Texture Module for MountainsMap

Transcription

1 2D Advanced Surface Texture Module for MountainsMap Advanced 2D profile filtering and analysis Advanced 2D filtering techniques 2D Fourier analysis & direct filtering of FFT plot Statistical analysis of series of 2D profiles Advanced data preparation. Fractal analysis MATLAB TM compatibility and more

2 Advanced data preparation remove anomalies, fill in missing data points, overcome instrument limitations The 2D Advanced Surface Texture optional module for MountainsMap includes numerous operators for advanced data preparation. Missing data points can be filled in automatically, anomalies can be removed by thresholding, profile resolution can be improved by resampling, profile points affected by random contamination can be retouched, and instrument limitations can be overcome by joining together multiple measured profiles. Advanced 2D filtering techniques the latest ISO filters for surface texture analysis and more The 2D Advanced Surface Texture optional module includes all of the filtering techniques needed to carry out advanced roughness/waviness analysis. They include form removal (required before roughness/waviness analysis), FFT-based filters from Gaussian to ISO 16610, and morphological filters. Form Removal Primary profile Form Roughness Waviness Roughness/waviness filters (FFT-based) FFT-based roughnesswaviness filtering techniques go all the way from the ISO Gaussian filter to the latest ISO Cubic Spline and Robust Gaussian filters. The cut-off is pre-selected or defined by the user and end effects can be managed automatically. 2

3 Compared to the Gaussian filter (upper right) the ISO robust Gaussian filter (lower right) improves the separation between waviness and roughness, reduces neighbouring peak and valley errors and, in particular, makes evaluations based upon the bearing ratio much more reliable. The robust Gaussian filter uses an iterative method based upon Gaussian regression and is already used in the automotive industry, notably in Germany. Gaussian filter (ISO 11562) with cut-off 0.08 mm Waviness profile (red) Roughness profile Waviness profile (red) Roughness profile Robust Gaussian filter (ISO 16610) with cut-off 0.08 mm Morphological filters and envelopes Dilation and erosion. In Morphological Filtering a structuring element (horizontal line segment or circular disk) is applied to an input profile. The fundamental operations are dilation and erosion. During dilation the structuring element is applied to the upper side of the profile. During erosion the structuring element is applied to the lower side of the profile. Top right: Input profile. Middle right: Dilated profile. Bottom right: Eroded profile. Profile before morphological filtering Dilation (structuring element: 0.05 mm horizontal line segment). Input profile (blue) Dilated profile (red) Input profile (blue) Texture Isotropy study: dominant surface Eroded profile (red) direction and parameters. Erosion (structuring element: 0.05 mm horizontal line segment). 3 3

4 Closing filter. A closing filter is a dilation followed by an erosion. When a closing filter is applied, valleys are closed (filled) but peaks are unchanged. The result is called the upper envelope of the input profile. Closing filter result (red) Closing filter (structuring element: 0.05 mm horizontal line segment). Opening filter. An opening filter is an erosion followed by a dilation. When an opening filter is applied, valleys are opened and peaks are reduced. The result is called the lower envelope of the input profile. Opening filter result (red) Opening filter (structuring element: 0.05 mm horizontal line segment). Morphological envelopes. The Morphological Envelopes study shows the upper envelope (result of the closing filter) and the lower envelope (result of the opening filter) on the input profile. Morphological envelopes based upon the application of closing and opening filters (structuring element: 0.05 mm horizontal line segment). Alternating sequence filters. In addition a closing filter can be applied followed by an opening filter or an opening filter can be applied followed by a closing filter. These alternating sequence filters eliminate tall and thin peaks and valleys. Closing then opening result (red) Alternating closing then opening filters (structuring element: 0.05 mm horizontal line segment). Opening then closing result (red) Alternating opening then closing filters (structuring element: 0.05 mm horizontal line segment). 4

5 MATLAB TM compatibility Design your own custom filters and apply them MATLABTM scripts can be executed by loading an m file or writing your own script. This makes it possible for users to develop and apply their own operators to studiables (measurement data sets). Note: Mountains 6 and MATLABTM must be installed on the same computer. 2D Fourier analysis and direct filtering understanding tool/process profile interaction The 2D Advanced Surface Texture optional module contains analytical studies that facilitate the study of tool/process surface interactions. They include a frequency spectrum plot, PSD (Power Spectrum Density) plot, and autocorrelation and intercorrelation plots. The module also comes with an FFT plot editor that makes it possible to exclude specified wavelengths from an input profile, for example for denoising. Frequency spectrum plot The Frequency Spectrum plot, based on the FFT, shows the magnitude and phase of each of the wavelengths in a profile, facilitating the analysis of periodic surfaces. Profile of a microlens array. Frequency spectrum. 5

6 PSD (power spectrum density) plot The Power Spectrum Density plot represents the dominant wavelengths in a profile. It can help to identify process and machine-tool problems in processes that are periodic or repetitive. Profile extracted from a turned surface. PSD plot (the wavelength is selected interactively using the slider). Autocorrelation plot The Autocorrelation plot can facilitate understanding of changes in more random processes. Profile extracted from a surface prepared by grinding. Autocorrelation plot of the profile. 6

7 FFT plot editor The FFT plot editor is used to exclude wavelengths within intervals that can be selected graphically on the FFT plot. See the simple example to the left. The input profile is shown at the top. Long wavelengths (red) are selected and excluded on the FFT plot editor. (Any wavelengths can be selected for exclusion. The ability to zoom up to x64 on the FFT plot facilitates wavelength selection.) The output profile is shown at the bottom. Excluded wavelengths 7

8 Fractal Analysis study the fractal dimension of a surface using two standard methods The Fractal Analysis study calculates a number of parameters for profiles using two methods: the enclosing boxes method and the morphological envelopes method. The number of enclosing boxes or the enclosed area is shown as a function of scale (the size of the boxes or structuring elements). The following parameters are calculated: Input profile for fractal analysis Fractal dimension (between 1 and 2 for a profile). Slope and correlation coefficient (R 2 ) of regression line(s). Enclosing boxes method Morphological envelopes method Creation and analysis of series of profiles generate statistics on parameters and step heights The 2D Advanced Surface Texture optional module can be used to create a series of profiles for basic statistical analysis. (The Statistics optional module is available for more advanced statistical analysis). Automatic conversion of a surface into a series of profiles. 3D surface measurement data can be displayed as a pseudo-color image and be automatically converted into a series of profiles for analysis. Manual definition of a series of profiles. Any set of measured profiles can be turned into a series of profiles. The profiles in the series can originate from a single surface or from multiple surfaces (for example in a production environment). Preprocessing of a series of profiles. Once a series of profiles has been created, new profiles can be added to the series and existing profiles in the series can be removed from it. Profiles in a series can be aligned automatically prior to analysis. Operators like leveling zooming, mirroring, flipping and resampling can be applied not only to individual profiles but also to a series of profiles. Analysis of a series of profiles. Analysis includes statistics on any set of 2D parameters and step height dimensions. 8

9 Statistics on 2D surface texture parameters (series of profiles) Profiles measured on a single surface or a series of surfaces. Series of profiles. Surface texture parameter table for the series of profiles including mean, min, max and standard deviation. 9

10 Statistical analysis of step heights (series of profiles) Pseudo color topographical image of a reference standard surface which is converted into a series of 1957 profiles for statistical analysis. Statistical analysis of 26 step heights after conversion of the surface into a series of 1957 profiles. It is possible to step through the profiles in the series one by one. 9

11 Selected features 2D Advanced Surface Texture Module for MountainsMap Extended instrument compatibility 3D profilers Pseudo-color image of surface topography with vertical scale. Extract point-to-point profiles Data preparation Remove anomalies (e.g. spikes) using thresholding. Fill in missing data points. Retouch existing profile points (e.g. to remove random contamination). Resample to improve image resolution. Join two profiles. Roughness/waviness filtering Form removal. Roughness/waviness filters: (ISO 1152 Gaussian, ISO double Gaussian, ISO cubic spline, ISO robust Gaussian) with default or user-defined cut-off and optional endeffect management. Morphological filtering Dilation and erosion operations using a line segment or disk as a structuring element. Closing (dilation followed by erosion), opening (erosion followed by opening) and sequential (closing followed by opening or opening followed by closing) operations. Upper and lower morphological envelopes generated by opening and closing operations. MATLAB TM compatibility Fractal analysis 2D Fourier analysis and filtering Series of profiles analysis (basic statistics) Execute MATLAB TM scripts by loading an m file or writing your own script. Develop and apply custom operators (MATLAB TM and MountainsMap must be installed on the same computer). Carry out fractal analysis using the enclosing boxes method or the morphological envelopes method. Calculate fractal dimension, slope and correlation coefficient (R 2 ) of regression line(s). Frequency spectrum plot. Power spectrum density plot. Autocorrelation and intercorrelation operations. FFT plot editor with optional thresholding for direct filtering/denoising. Convert a surface into a series of profiles for basic statistical analysis. Create a series of profiles from any set of profile measurements on the same surface or on different surfaces. Level, zoom, mirror, flip, resample a series of profiles. Automatic lateral alignment of profiles in a series. Display Abbott-Firestone curve and depth histogram for every profile in the series. Generate statistics on a series of step heights: mean, min, max and total height, width. Parameter tables for the series with mean, standard deviation, min, max, median, range, variance, quartiles, etc. Doc revision: Digital Surf Head Office & R&D Center 16 rue Lavoisier, Besançon, France Tel contact@digitalsurf.com Digital Surf. All rights reserved. Specifications subject to change without prior notice.