Changes between Version 117 and Version 118 of UvmatHelp


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Timestamp:
Dec 6, 2014, 4:31:41 PM (6 years ago)
Author:
sommeria
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  • UvmatHelp

    v117 v118  
    172172   * Intensity < 20: ('black mask') the vector in this place will be set to zero
    173173   * 20 < Intensity < 200:('gray mask') the vector in this place will be absent
    174    * Intensity>200  the vector will be computed  The mask corresponding to an image or velocity field can be displayed in '''uvmat.fig''' by selecting the check box '''[view_mask]([CheckMask])''' on the upper left. Images with appropriate name can be automatically recognised by '''uvmat.fig''' and civ functions, see [#a9-Masksandgrids section 9.1]. Otherwise file selection by a browser is proposed when '''[view_mask]''' is selected.
     174   * Intensity>200  the vector will be computed  The mask corresponding to an image or velocity field can be displayed in '''uvmat.fig''' by selecting the check box '''[view_mask]([!CheckMask])''' on the upper left. Images with appropriate name can be automatically recognised by '''uvmat.fig''' and civ functions, see [#a9-Masksandgrids section 9.1]. Otherwise file selection by a browser is proposed when '''[view_mask]''' is selected.
    175175
    176176 * ''' Grid:''' List of numbers (in ASCII text) specifying the set of points where the PIV processing is performed. It specifies the number of points n and a corresponding list of x and y coordinates expressed in image pixels, as follows
     
    231231[[Image(help_scalar_titres.jpg)]]
    232232
    233 The greyscale images are described by a matrix A(npy,npx) of positive integers. The luminosity range depends on the camera dynamics (0 to 255 for 8 bit images, 0 to 65535 for 16 bit images). Luminosity represented with grey levels, according to the colorbar displayed on the right. The luminosity and contrast can be adjusted using the edit boxes '''[num_MinA]''' and '''[num_MaxA]''' : the luminosity level set by '''[num_MinA]''' (and levels below) is represented as black, and the luminosity level set by '''[num_MaxA]''' (or levels above) as white. When the check box '''[!CheckFixScalar]''' is not selected, these bounds are set automatically to the image minimum and maximum respectively. Then the image may appear dark if a single point is very bright, in that case a lower value must be set by '''[num_MaxA]'''. Greyscale images can be displayed with false colors, from blue to red, by unselecting the check box '''[CheckBW]'''.
     233The greyscale images are described by a matrix A(npy,npx) of positive integers. The luminosity range depends on the camera dynamics (0 to 255 for 8 bit images, 0 to 65535 for 16 bit images). Luminosity represented with grey levels, according to the colorbar displayed on the right. The luminosity and contrast can be adjusted using the edit boxes '''[num_MinA]''' and '''[num_MaxA]''' : the luminosity level set by '''[num_MinA]''' (and levels below) is represented as black, and the luminosity level set by '''[num_MaxA]''' (or levels above) as white. When the check box '''[!CheckFixScalar]''' is not selected, these bounds are set automatically to the image minimum and maximum respectively. Then the image may appear dark if a single point is very bright, in that case a lower value must be set by '''[num_MaxA]'''. Greyscale images can be displayed with false colors, from blue to red, by unselecting the check box '''[!CheckBW]'''.
    234234
    235235Note that greyscale images with low resolution are linearly interpolated on a finer mesh for nicer display. This interpolation can be also done as image processing by defining a grid on a projection object 'plane', see [#ProjObject section 6].
     
    237237Two images can be visually compared by switching back and forth between them as a short movie. This is quite useful to get a visual feeling of the image correlation for PIV. This effect is obtained by introducing two image indices in the edit boxes j1 and j2 (or i1 and i2), and selecting the button  '''[movie_pair] ''' (''''[<-->]'''') to switch between these two indices. The speed of the movie can be adjusted by the slider '''[speed]'''. Press '''[movie_pair] ''' again, or '''[STOP]''', to stop the motion.
    238238
    239 Scalar fields are  represented like greyscale images, by default with a false color map ranging from blue (minimum values) to red (maximum), or as gray scale images by selecting the check box '''[CheckBW]'''. Other color maps can be used by extracting the figure with the menu bar button '''[Export/extract figure]''', then using the standard  Matlab button '''[!Edit/Colormap]''' in the figure menu bar.
     239Scalar fields are  represented like greyscale images, by default with a false color map ranging from blue (minimum values) to red (maximum), or as gray scale images by selecting the check box '''[!CheckBW]'''. Other color maps can be used by extracting the figure with the menu bar button '''[Export/extract figure]''', then using the standard  Matlab button '''[!Edit/Colormap]''' in the figure menu bar.
    240240
    241241Scalar are represented by matrices with real ('double') values, unlike images which are integers. They can be alternatively defined with unstructured grid (see [#a5.1Gridingofdata section 5.1]): they are then linearly interpolated on a regular grid before visualisation (a fairly slow process).
     
    244244Scalars (or image intensity) can be also represented with contour plots, by switching the popup menu '''[Contours] ''' from the setting 'image' to the setting 'contours'. Contours for positive scalar values are in sold line while contours for negative values are dashed. The interval between contours can be set by the edit box '''[num_IncrA]'''. The interval is automatically determined if the box content is blank.
    245245
    246 By default, the  contours are further marked by jumps of color levels. This can be set to grey levels by selecting the check box '''[CheckBW]. '''To suppress these images, set '''[Opacity]''' to 0. '''''''''''
     246By default, the  contours are further marked by jumps of color levels. This can be set to grey levels by selecting the check box '''[!CheckBW]. '''To suppress these images, set '''[Opacity]''' to 0. '''''''''''
    247247
    248248=== 4.3 Vectors ===
     
    498498 * ''' !ProjMode 'none', 'mask_inside', 'mask_outside': ''' no projection operation. The object is used solely for plotting purpose, to show a boundary or to prepare a mask, inside or outside a closed line, see [#a9-Masksandgrids section 9]).
    499499
    500 Operations, for instance 'vort', 'div' are performed after interpolation. Similarly for field difference, which requires interpolation to compare fields defined at different positions. Field variables to be substracted are initially marqued by an attribute 'CheckSub'.
     500Operations, for instance 'vort', 'div' are performed after interpolation. Similarly for field difference, which requires interpolation to compare fields defined at different positions. Field variables to be substracted are initially marqued by an attribute '!CheckSub'.
    501501
    502502=== 6.4 Object representation ===