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
