[Insight-users] Re: Visualizing Vector Fields ... with ParaView

[Luis Ibanez]

Hi Hari,


You probably are using now ParaView 1.2.1
(which is an updated release).

       http://www.paraview.org


A couple of things have changed in ParaView since
the message below was posted in december 2003.


For example:

1) Now you can read MetaImage fileformat directly
    (they can contain scalar or vector images)

2) ExtractVOI is now called ExtractGrid
    (as you already noticed)


The simple way of visualizing deformation fields now is to
load your MetaImage file containing the vector image and
directly select the filter "Glyph", and in the options of
the glyph filter set:

   a) Orient Mode = Vector
   b) Scale Mode  = Vector Magnitude
   c) Scale Factor = play with this value to scale your vectors


The reason for using ExtractGrid is to subsample the original
vector image. This is only needed if your deformation field
has a large number of pixels (~ high resolution). Otherwise
you can simply use the Glyph filter connected directly at the
output of the reader.



Please let us know if you find any problems.



Thanks


    Luis



-------------------------


Hari Sundar wrote:

> Hi,
> 
> I have been using ITK to output some deformation fields and tried to use
> paraview to visualize the deformation vectors. I based this on this post
> by Luis Ibanez
> 
> http://www.itk.org/pipermail/insight-users/2003-December/005865.html
> 
> However, I have been unable to get this to work properly. Firstly, I do
> not get an option to set the scale mode to scalar. I tried all the other
> options and still don't see anything. If I set the scale to "Dat Scaling
> Off", I can see the allows, but they are all aligned in the same direction
> (+ve X axis). My deformation fields are all right, because I wrote it out
> like and image (x,y,z = r,g,b) and it does display something ...
> 
> What do I need for the glyph to display properly.
> 
> thanks,
> -Hari
> 
> PS: I used ExtractGrid in place of ExtractVOI.
>