I have now followed your advise and I no longer get negative values which is good. But I still cannot make any sense out of the histogram.
I have tried to make a histogram showing the following 3 types of information: 1) bin_values http://37133.vs.webtropia.com/apache2-default/test/hist1.jpg 2) GlyphVector_total (Magnitude) http://37133.vs.webtropia.com/apache2-default/test/hist2.jpg 3) GlyphVector_average (Magnitude) http://37133.vs.webtropia.com/apache2-default/test/hist3.jpg As I understand the magnitude of the vectors are shown along the x-axis. This means that no vectors have 0 magnitude and the max magnitude is 5.11 units. But what is plotted along the y-axis? The input image contains 512*512= 262144 pixels. But the sum of the blocks in the above histograms exceeds this number so it cannot be the pixel count. What is plotted along the y-axis? On Wed, Nov 4, 2009 at 1:30 PM, Utkarsh Ayachit <[email protected]> wrote: > On the properties panel for the Histogram filter, you choose the array > to generate histogram from. Currently the panel doesn't not support > selecting the magnitude of a vector array (only 1 component). In your > case, by default the 0th component of the GlyphVector is chosen, which > can be negative and hence the plot. > > To generate a histogram for the magnitude of the vector, apply another > calculator with the expression: > > mag(GlyphVector) > > and then generate a histogram using the "Result" array. > > Utkarsh > > On Tue, Nov 3, 2009 at 8:15 PM, motes motes <[email protected]> wrote: >> I have loaded a deformation field (.mhd file) in paraview made with itk: >> >> 1) open .mhd file >> 2) connect the calculate and use the below expression: >> >> MetaImage_X*iHat+MetaImage_Y*jHat+0*kHat >> >> 3) Add glyph filter. >> >> The result looks like this: >> >> http://37133.vs.webtropia.com/apache2-default/test/deform.png >> >> >> But now I would like to create a histogram over the magnitude of the >> deformation field. I have therefore selected: Filters->Data >> Analysis->Histogram. >> >> In the display tab I have selected GlypVector_total (Magnitude) and >> under "User Data Array" I have selected MetaImage. The result looks >> like this: >> >> http://37133.vs.webtropia.com/apache2-default/test/hist.png >> >> But how should it be interpretated? I assume that the y-axis is the >> pixel count and the x-axis is the magnitude size. But should the >> magnitudes (Norm) not always be positive? >> >> And as can be seen from the deformation field its only a small part of >> the image that is deformed. I would therefore expect a large number of >> pixels to have 0 magnitude, but that is not the case. >> >> Any input are welcome! >> _______________________________________________ >> Powered by www.kitware.com >> >> Visit other Kitware open-source projects at >> http://www.kitware.com/opensource/opensource.html >> >> Please keep messages on-topic and check the ParaView Wiki at: >> http://paraview.org/Wiki/ParaView >> >> Follow this link to subscribe/unsubscribe: >> http://www.paraview.org/mailman/listinfo/paraview >> > _______________________________________________ Powered by www.kitware.com Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Please keep messages on-topic and check the ParaView Wiki at: http://paraview.org/Wiki/ParaView Follow this link to subscribe/unsubscribe: http://www.paraview.org/mailman/listinfo/paraview
